Merge #4226

4226: Hybrid search r=dureuill a=dureuill

Allows to perform hybrid search requests that combine the results of semantic and keyword search and automatically generate embeddings.

## How to use

See [feature description](https://meilisearch.notion.site/v1-6-Hybrid-Search-Embedders-ea42c82f90cc4bc0be1eeb917c1118c8)

## Changes

- work is based on #4213 
- milli::new search now takes an input universe directly, rather than computing it from a filter. This adds flexibility to require results on a subset of documents
- vector search is now a regular ranking rule (akin to sort and geosort) and reports its score as a ScoreDetail
- separate keyword search and vector search functions, vector search now respects (geo)sort ranking rules
- add automatic embedding
- add hybrid search

Co-authored-by: Louis Dureuil <louis@meilisearch.com>
Co-authored-by: ManyTheFish <many@meilisearch.com>

dump/src/lib.rs

@@ -276,6 +276,7 @@ pub(crate) mod test {
                 ),
             }),
             pagination: Setting::NotSet,
+            embedders: Setting::NotSet,
             _kind: std::marker::PhantomData,
         };
         settings.check()

dump/src/reader/compat/v5_to_v6.rs

@@ -378,6 +378,7 @@ impl<T> From<v5::Settings<T>> for v6::Settings<v6::Unchecked> {
                 v5::Setting::Reset => v6::Setting::Reset,
                 v5::Setting::NotSet => v6::Setting::NotSet,
             },
+            embedders: v6::Setting::NotSet,
             _kind: std::marker::PhantomData,
         }
     }

index-scheduler/src/batch.rs

@@ -1202,6 +1202,10 @@ impl IndexScheduler {
 
                 let config = IndexDocumentsConfig { update_method: method, ..Default::default() };
 
+                let embedder_configs = index.embedding_configs(index_wtxn)?;
+                // TODO: consider Arc'ing the map too (we only need read access + we'll be cloning it multiple times, so really makes sense)
+                let embedders = self.embedders(embedder_configs)?;
+
                 let mut builder = milli::update::IndexDocuments::new(
                     index_wtxn,
                     index,
@@ -1220,6 +1224,8 @@ impl IndexScheduler {
                             let (new_builder, user_result) = builder.add_documents(reader)?;
                             builder = new_builder;
 
+                            builder = builder.with_embedders(embedders.clone());
+
                             let received_documents =
                                 if let Some(Details::DocumentAdditionOrUpdate {
                                     received_documents,
@@ -1345,6 +1351,9 @@ impl IndexScheduler {
 
                 for (task, (_, settings)) in tasks.iter_mut().zip(settings) {
                     let checked_settings = settings.clone().check();
+                    if matches!(checked_settings.embedders, milli::update::Setting::Set(_)) {
+                        self.features().check_vector("Passing `embedders` in settings")?
+                    }
                     if checked_settings.proximity_precision.set().is_some() {
                         self.features.features().check_proximity_precision()?;
                     }

index-scheduler/src/features.rs

@@ -56,12 +56,12 @@ impl RoFeatures {
         }
     }
 
-    pub fn check_vector(&self) -> Result<()> {
+    pub fn check_vector(&self, disabled_action: &'static str) -> Result<()> {
         if self.runtime.vector_store {
             Ok(())
         } else {
             Err(FeatureNotEnabledError {
-                disabled_action: "Passing `vector` as a query parameter",
+                disabled_action,
                 feature: "vector store",
                 issue_link: "https://github.com/meilisearch/product/discussions/677",
             }

index-scheduler/src/insta_snapshot.rs

@@ -41,6 +41,7 @@ pub fn snapshot_index_scheduler(scheduler: &IndexScheduler) -> String {
         planned_failures: _,
         run_loop_iteration: _,
         currently_updating_index: _,
+        embedders: _,
     } = scheduler;
 
     let rtxn = env.read_txn().unwrap();

index-scheduler/src/lib.rs

@@ -52,6 +52,7 @@ use meilisearch_types::heed::types::{SerdeBincode, SerdeJson, Str, I128};
 use meilisearch_types::heed::{self, Database, Env, PutFlags, RoTxn, RwTxn};
 use meilisearch_types::milli::documents::DocumentsBatchBuilder;
 use meilisearch_types::milli::update::IndexerConfig;
+use meilisearch_types::milli::vector::{Embedder, EmbedderOptions, EmbeddingConfigs};
 use meilisearch_types::milli::{self, CboRoaringBitmapCodec, Index, RoaringBitmapCodec, BEU32};
 use meilisearch_types::tasks::{Kind, KindWithContent, Status, Task};
 use puffin::FrameView;
@@ -341,6 +342,8 @@ pub struct IndexScheduler {
     /// so that a handle to the index is available from other threads (search) in an optimized manner.
     currently_updating_index: Arc<RwLock<Option<(String, Index)>>>,
 
+    embedders: Arc<RwLock<HashMap<EmbedderOptions, Arc<Embedder>>>>,
+
     // ================= test
     // The next entry is dedicated to the tests.
     /// Provide a way to set a breakpoint in multiple part of the scheduler.
@@ -386,6 +389,7 @@ impl IndexScheduler {
             auth_path: self.auth_path.clone(),
             version_file_path: self.version_file_path.clone(),
             currently_updating_index: self.currently_updating_index.clone(),
+            embedders: self.embedders.clone(),
             #[cfg(test)]
             test_breakpoint_sdr: self.test_breakpoint_sdr.clone(),
             #[cfg(test)]
@@ -484,6 +488,7 @@ impl IndexScheduler {
             auth_path: options.auth_path,
             version_file_path: options.version_file_path,
             currently_updating_index: Arc::new(RwLock::new(None)),
+            embedders: Default::default(),
 
             #[cfg(test)]
             test_breakpoint_sdr,
@@ -1333,6 +1338,40 @@ impl IndexScheduler {
         }
     }
 
+    // TODO: consider using a type alias or a struct embedder/template
+    pub fn embedders(
+        &self,
+        embedding_configs: Vec<(String, milli::vector::EmbeddingConfig)>,
+    ) -> Result<EmbeddingConfigs> {
+        let res: Result<_> = embedding_configs
+            .into_iter()
+            .map(|(name, milli::vector::EmbeddingConfig { embedder_options, prompt })| {
+                let prompt =
+                    Arc::new(prompt.try_into().map_err(meilisearch_types::milli::Error::from)?);
+                // optimistically return existing embedder
+                {
+                    let embedders = self.embedders.read().unwrap();
+                    if let Some(embedder) = embedders.get(&embedder_options) {
+                        return Ok((name, (embedder.clone(), prompt)));
+                    }
+                }
+
+                // add missing embedder
+                let embedder = Arc::new(
+                    Embedder::new(embedder_options.clone())
+                        .map_err(meilisearch_types::milli::vector::Error::from)
+                        .map_err(meilisearch_types::milli::Error::from)?,
+                );
+                {
+                    let mut embedders = self.embedders.write().unwrap();
+                    embedders.insert(embedder_options, embedder.clone());
+                }
+                Ok((name, (embedder, prompt)))
+            })
+            .collect();
+        res.map(EmbeddingConfigs::new)
+    }
+
     /// Blocks the thread until the test handle asks to progress to/through this breakpoint.
     ///
     /// Two messages are sent through the channel for each breakpoint.

meilisearch-types/src/deserr/mod.rs

@@ -188,3 +188,4 @@ merge_with_error_impl_take_error_message!(ParseOffsetDateTimeError);
 merge_with_error_impl_take_error_message!(ParseTaskKindError);
 merge_with_error_impl_take_error_message!(ParseTaskStatusError);
 merge_with_error_impl_take_error_message!(IndexUidFormatError);
+merge_with_error_impl_take_error_message!(InvalidSearchSemanticRatio);

meilisearch-types/src/error.rs

@@ -222,6 +222,8 @@ InvalidVectorsType                    , InvalidRequest       , BAD_REQUEST ;
 InvalidDocumentId                     , InvalidRequest       , BAD_REQUEST ;
 InvalidDocumentLimit                  , InvalidRequest       , BAD_REQUEST ;
 InvalidDocumentOffset                 , InvalidRequest       , BAD_REQUEST ;
+InvalidEmbedder                       , InvalidRequest       , BAD_REQUEST ;
+InvalidHybridQuery                    , InvalidRequest       , BAD_REQUEST ;
 InvalidIndexLimit                     , InvalidRequest       , BAD_REQUEST ;
 InvalidIndexOffset                    , InvalidRequest       , BAD_REQUEST ;
 InvalidIndexPrimaryKey                , InvalidRequest       , BAD_REQUEST ;
@@ -233,6 +235,7 @@ InvalidSearchAttributesToRetrieve     , InvalidRequest       , BAD_REQUEST ;
 InvalidSearchCropLength               , InvalidRequest       , BAD_REQUEST ;
 InvalidSearchCropMarker               , InvalidRequest       , BAD_REQUEST ;
 InvalidSearchFacets                   , InvalidRequest       , BAD_REQUEST ;
+InvalidSearchSemanticRatio            , InvalidRequest       , BAD_REQUEST ;
 InvalidFacetSearchFacetName           , InvalidRequest       , BAD_REQUEST ;
 InvalidSearchFilter                   , InvalidRequest       , BAD_REQUEST ;
 InvalidSearchHighlightPostTag         , InvalidRequest       , BAD_REQUEST ;
@@ -256,6 +259,7 @@ InvalidSettingsProximityPrecision     , InvalidRequest       , BAD_REQUEST ;
 InvalidSettingsFaceting               , InvalidRequest       , BAD_REQUEST ;
 InvalidSettingsFilterableAttributes   , InvalidRequest       , BAD_REQUEST ;
 InvalidSettingsPagination             , InvalidRequest       , BAD_REQUEST ;
+InvalidSettingsEmbedders              , InvalidRequest       , BAD_REQUEST ;
 InvalidSettingsRankingRules           , InvalidRequest       , BAD_REQUEST ;
 InvalidSettingsSearchableAttributes   , InvalidRequest       , BAD_REQUEST ;
 InvalidSettingsSortableAttributes     , InvalidRequest       , BAD_REQUEST ;
@@ -295,15 +299,18 @@ MissingFacetSearchFacetName           , InvalidRequest       , BAD_REQUEST ;
 MissingIndexUid                       , InvalidRequest       , BAD_REQUEST ;
 MissingMasterKey                      , Auth                 , UNAUTHORIZED ;
 MissingPayload                        , InvalidRequest       , BAD_REQUEST ;
+MissingSearchHybrid                   , InvalidRequest       , BAD_REQUEST ;
 MissingSwapIndexes                    , InvalidRequest       , BAD_REQUEST ;
 MissingTaskFilters                    , InvalidRequest       , BAD_REQUEST ;
 NoSpaceLeftOnDevice                   , System               , UNPROCESSABLE_ENTITY;
 PayloadTooLarge                       , InvalidRequest       , PAYLOAD_TOO_LARGE ;
 TaskNotFound                          , InvalidRequest       , NOT_FOUND ;
 TooManyOpenFiles                      , System               , UNPROCESSABLE_ENTITY ;
+TooManyVectors                        , InvalidRequest       , BAD_REQUEST ;
 UnretrievableDocument                 , Internal             , BAD_REQUEST ;
 UnretrievableErrorCode                , InvalidRequest       , BAD_REQUEST ;
-UnsupportedMediaType                  , InvalidRequest       , UNSUPPORTED_MEDIA_TYPE
+UnsupportedMediaType                  , InvalidRequest       , UNSUPPORTED_MEDIA_TYPE ;
+VectorEmbeddingError                  , InvalidRequest       , BAD_REQUEST
 }
 
 impl ErrorCode for JoinError {
@@ -336,6 +343,10 @@ impl ErrorCode for milli::Error {
                     UserError::InvalidDocumentId { .. } | UserError::TooManyDocumentIds { .. } => {
                         Code::InvalidDocumentId
                     }
+                    UserError::MissingDocumentField(_) => Code::InvalidDocumentFields,
+                    UserError::InvalidPrompt(_) => Code::InvalidSettingsEmbedders,
+                    UserError::TooManyEmbedders(_) => Code::InvalidSettingsEmbedders,
+                    UserError::InvalidPromptForEmbeddings(..) => Code::InvalidSettingsEmbedders,
                     UserError::NoPrimaryKeyCandidateFound => Code::IndexPrimaryKeyNoCandidateFound,
                     UserError::MultiplePrimaryKeyCandidatesFound { .. } => {
                         Code::IndexPrimaryKeyMultipleCandidatesFound
@@ -353,11 +364,15 @@ impl ErrorCode for milli::Error {
                     UserError::CriterionError(_) => Code::InvalidSettingsRankingRules,
                     UserError::InvalidGeoField { .. } => Code::InvalidDocumentGeoField,
                     UserError::InvalidVectorDimensions { .. } => Code::InvalidVectorDimensions,
+                    UserError::InvalidVectorsMapType { .. } => Code::InvalidVectorsType,
                     UserError::InvalidVectorsType { .. } => Code::InvalidVectorsType,
+                    UserError::TooManyVectors(_, _) => Code::TooManyVectors,
                     UserError::SortError(_) => Code::InvalidSearchSort,
                     UserError::InvalidMinTypoWordLenSetting(_, _) => {
                         Code::InvalidSettingsTypoTolerance
                     }
+                    UserError::InvalidEmbedder(_) => Code::InvalidEmbedder,
+                    UserError::VectorEmbeddingError(_) => Code::VectorEmbeddingError,
                 }
             }
         }
@@ -445,6 +460,15 @@ impl fmt::Display for DeserrParseIntError {
     }
 }
 
+impl fmt::Display for deserr_codes::InvalidSearchSemanticRatio {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(
+            f,
+            "the value of `semanticRatio` is invalid, expected a float between `0.0` and `1.0`."
+        )
+    }
+}
+
 #[macro_export]
 macro_rules! internal_error {
     ($target:ty : $($other:path), *) => {

meilisearch-types/src/settings.rs

@@ -199,6 +199,10 @@ pub struct Settings<T> {
     #[deserr(default, error = DeserrJsonError<InvalidSettingsPagination>)]
     pub pagination: Setting<PaginationSettings>,
 
+    #[serde(default, skip_serializing_if = "Setting::is_not_set")]
+    #[deserr(default, error = DeserrJsonError<InvalidSettingsEmbedders>)]
+    pub embedders: Setting<BTreeMap<String, Setting<milli::vector::settings::EmbeddingSettings>>>,
+
     #[serde(skip)]
     #[deserr(skip)]
     pub _kind: PhantomData<T>,
@@ -222,6 +226,7 @@ impl Settings<Checked> {
             typo_tolerance: Setting::Reset,
             faceting: Setting::Reset,
             pagination: Setting::Reset,
+            embedders: Setting::Reset,
             _kind: PhantomData,
         }
     }
@@ -243,6 +248,7 @@ impl Settings<Checked> {
             typo_tolerance,
             faceting,
             pagination,
+            embedders,
             ..
         } = self;
 
@@ -262,6 +268,7 @@ impl Settings<Checked> {
             typo_tolerance,
             faceting,
             pagination,
+            embedders,
             _kind: PhantomData,
         }
     }
@@ -307,6 +314,7 @@ impl Settings<Unchecked> {
             typo_tolerance: self.typo_tolerance,
             faceting: self.faceting,
             pagination: self.pagination,
+            embedders: self.embedders,
             _kind: PhantomData,
         }
     }
@@ -490,6 +498,12 @@ pub fn apply_settings_to_builder(
         Setting::Reset => builder.reset_pagination_max_total_hits(),
         Setting::NotSet => (),
     }
+
+    match settings.embedders.clone() {
+        Setting::Set(value) => builder.set_embedder_settings(value),
+        Setting::Reset => builder.reset_embedder_settings(),
+        Setting::NotSet => (),
+    }
 }
 
 pub fn settings(
@@ -571,6 +585,12 @@ pub fn settings(
         ),
     };
 
+    let embedders = index
+        .embedding_configs(rtxn)?
+        .into_iter()
+        .map(|(name, config)| (name, Setting::Set(config.into())))
+        .collect();
+
     Ok(Settings {
         displayed_attributes: match displayed_attributes {
             Some(attrs) => Setting::Set(attrs),
@@ -599,6 +619,7 @@ pub fn settings(
         typo_tolerance: Setting::Set(typo_tolerance),
         faceting: Setting::Set(faceting),
         pagination: Setting::Set(pagination),
+        embedders: Setting::Set(embedders),
         _kind: PhantomData,
     })
 }
@@ -747,6 +768,7 @@ pub(crate) mod test {
             typo_tolerance: Setting::NotSet,
             faceting: Setting::NotSet,
             pagination: Setting::NotSet,
+            embedders: Setting::NotSet,
             _kind: PhantomData::<Unchecked>,
         };
 
@@ -772,6 +794,7 @@ pub(crate) mod test {
             typo_tolerance: Setting::NotSet,
             faceting: Setting::NotSet,
             pagination: Setting::NotSet,
+            embedders: Setting::NotSet,
             _kind: PhantomData::<Unchecked>,
         };
 

meilisearch/src/analytics/segment_analytics.rs

@@ -36,7 +36,7 @@ use crate::routes::{create_all_stats, Stats};
 use crate::search::{
     FacetSearchResult, MatchingStrategy, SearchQuery, SearchQueryWithIndex, SearchResult,
     DEFAULT_CROP_LENGTH, DEFAULT_CROP_MARKER, DEFAULT_HIGHLIGHT_POST_TAG,
-    DEFAULT_HIGHLIGHT_PRE_TAG, DEFAULT_SEARCH_LIMIT,
+    DEFAULT_HIGHLIGHT_PRE_TAG, DEFAULT_SEARCH_LIMIT, DEFAULT_SEMANTIC_RATIO,
 };
 use crate::Opt;
 
@@ -586,6 +586,11 @@ pub struct SearchAggregator {
     // vector
     // The maximum number of floats in a vector request
     max_vector_size: usize,
+    // Whether the semantic ratio passed to a hybrid search equals the default ratio.
+    semantic_ratio: bool,
+    // Whether a non-default embedder was specified
+    embedder: bool,
+    hybrid: bool,
 
     // every time a search is done, we increment the counter linked to the used settings
     matching_strategy: HashMap<String, usize>,
@@ -639,6 +644,7 @@ impl SearchAggregator {
             crop_marker,
             matching_strategy,
             attributes_to_search_on,
+            hybrid,
         } = query;
 
         let mut ret = Self::default();
@@ -712,6 +718,12 @@ impl SearchAggregator {
         ret.show_ranking_score = *show_ranking_score;
         ret.show_ranking_score_details = *show_ranking_score_details;
 
+        if let Some(hybrid) = hybrid {
+            ret.semantic_ratio = hybrid.semantic_ratio != DEFAULT_SEMANTIC_RATIO();
+            ret.embedder = hybrid.embedder.is_some();
+            ret.hybrid = true;
+        }
+
         ret
     }
 
@@ -765,6 +777,9 @@ impl SearchAggregator {
             facets_total_number_of_facets,
             show_ranking_score,
             show_ranking_score_details,
+            semantic_ratio,
+            embedder,
+            hybrid,
         } = other;
 
         if self.timestamp.is_none() {
@@ -810,6 +825,9 @@ impl SearchAggregator {
 
         // vector
         self.max_vector_size = self.max_vector_size.max(max_vector_size);
+        self.semantic_ratio |= semantic_ratio;
+        self.hybrid |= hybrid;
+        self.embedder |= embedder;
 
         // pagination
         self.max_limit = self.max_limit.max(max_limit);
@@ -878,6 +896,9 @@ impl SearchAggregator {
             facets_total_number_of_facets,
             show_ranking_score,
             show_ranking_score_details,
+            semantic_ratio,
+            embedder,
+            hybrid,
         } = self;
 
         if total_received == 0 {
@@ -917,6 +938,11 @@ impl SearchAggregator {
                 "vector": {
                     "max_vector_size": max_vector_size,
                 },
+                "hybrid": {
+                    "enabled": hybrid,
+                    "semantic_ratio": semantic_ratio,
+                    "embedder": embedder,
+                },
                 "pagination": {
                    "max_limit": max_limit,
                    "max_offset": max_offset,
@@ -1012,6 +1038,7 @@ impl MultiSearchAggregator {
                     crop_marker: _,
                     matching_strategy: _,
                     attributes_to_search_on: _,
+                    hybrid: _,
                 } = query;
 
                 index_uid.as_str()
@@ -1158,6 +1185,7 @@ impl FacetSearchAggregator {
             filter,
             matching_strategy,
             attributes_to_search_on,
+            hybrid,
         } = query;
 
         let mut ret = Self::default();
@@ -1171,7 +1199,8 @@ impl FacetSearchAggregator {
             || vector.is_some()
             || filter.is_some()
             || *matching_strategy != MatchingStrategy::default()
-            || attributes_to_search_on.is_some();
+            || attributes_to_search_on.is_some()
+            || hybrid.is_some();
 
         ret
     }

meilisearch/src/error.rs

@@ -51,6 +51,8 @@ pub enum MeilisearchHttpError {
     DocumentFormat(#[from] DocumentFormatError),
     #[error(transparent)]
     Join(#[from] JoinError),
+    #[error("Invalid request: missing `hybrid` parameter when both `q` and `vector` are present.")]
+    MissingSearchHybrid,
 }
 
 impl ErrorCode for MeilisearchHttpError {
@@ -74,6 +76,7 @@ impl ErrorCode for MeilisearchHttpError {
             MeilisearchHttpError::FileStore(_) => Code::Internal,
             MeilisearchHttpError::DocumentFormat(e) => e.error_code(),
             MeilisearchHttpError::Join(_) => Code::Internal,
+            MeilisearchHttpError::MissingSearchHybrid => Code::MissingSearchHybrid,
         }
     }
 }

meilisearch/src/main.rs

@@ -19,7 +19,11 @@ static ALLOC: mimalloc::MiMalloc = mimalloc::MiMalloc;
 /// does all the setup before meilisearch is launched
 fn setup(opt: &Opt) -> anyhow::Result<()> {
     let mut log_builder = env_logger::Builder::new();
-    log_builder.parse_filters(&opt.log_level.to_string());
+    let log_filters = format!(
+        "{},h2=warn,hyper=warn,tokio_util=warn,tracing=warn,rustls=warn,mio=warn,reqwest=warn",
+        opt.log_level
+    );
+    log_builder.parse_filters(&log_filters);
 
     log_builder.init();
 

meilisearch/src/routes/indexes/facet_search.rs

@@ -13,9 +13,9 @@ use crate::analytics::{Analytics, FacetSearchAggregator};
 use crate::extractors::authentication::policies::*;
 use crate::extractors::authentication::GuardedData;
 use crate::search::{
-    add_search_rules, perform_facet_search, MatchingStrategy, SearchQuery, DEFAULT_CROP_LENGTH,
+    add_search_rules, perform_facet_search, HybridQuery, MatchingStrategy, SearchQuery,
-    DEFAULT_CROP_MARKER, DEFAULT_HIGHLIGHT_POST_TAG, DEFAULT_HIGHLIGHT_PRE_TAG,
+    DEFAULT_CROP_LENGTH, DEFAULT_CROP_MARKER, DEFAULT_HIGHLIGHT_POST_TAG,
-    DEFAULT_SEARCH_LIMIT, DEFAULT_SEARCH_OFFSET,
+    DEFAULT_HIGHLIGHT_PRE_TAG, DEFAULT_SEARCH_LIMIT, DEFAULT_SEARCH_OFFSET,
 };
 
 pub fn configure(cfg: &mut web::ServiceConfig) {
@@ -36,6 +36,8 @@ pub struct FacetSearchQuery {
     pub q: Option<String>,
     #[deserr(default, error = DeserrJsonError<InvalidSearchVector>)]
     pub vector: Option<Vec<f32>>,
+    #[deserr(default, error = DeserrJsonError<InvalidHybridQuery>)]
+    pub hybrid: Option<HybridQuery>,
     #[deserr(default, error = DeserrJsonError<InvalidSearchFilter>)]
     pub filter: Option<Value>,
     #[deserr(default, error = DeserrJsonError<InvalidSearchMatchingStrategy>, default)]
@@ -95,6 +97,7 @@ impl From<FacetSearchQuery> for SearchQuery {
             filter,
             matching_strategy,
             attributes_to_search_on,
+            hybrid,
         } = value;
 
         SearchQuery {
@@ -119,6 +122,7 @@ impl From<FacetSearchQuery> for SearchQuery {
             matching_strategy,
             vector,
             attributes_to_search_on,
+            hybrid,
         }
     }
 }

meilisearch/src/routes/indexes/search.rs

@@ -2,12 +2,14 @@ use actix_web::web::Data;
 use actix_web::{web, HttpRequest, HttpResponse};
 use deserr::actix_web::{AwebJson, AwebQueryParameter};
 use index_scheduler::IndexScheduler;
-use log::debug;
+use log::{debug, warn};
 use meilisearch_types::deserr::query_params::Param;
 use meilisearch_types::deserr::{DeserrJsonError, DeserrQueryParamError};
 use meilisearch_types::error::deserr_codes::*;
 use meilisearch_types::error::ResponseError;
 use meilisearch_types::index_uid::IndexUid;
+use meilisearch_types::milli;
+use meilisearch_types::milli::vector::DistributionShift;
 use meilisearch_types::serde_cs::vec::CS;
 use serde_json::Value;
 
@@ -16,9 +18,9 @@ use crate::extractors::authentication::policies::*;
 use crate::extractors::authentication::GuardedData;
 use crate::extractors::sequential_extractor::SeqHandler;
 use crate::search::{
-    add_search_rules, perform_search, MatchingStrategy, SearchQuery, DEFAULT_CROP_LENGTH,
+    add_search_rules, perform_search, HybridQuery, MatchingStrategy, SearchQuery, SemanticRatio,
-    DEFAULT_CROP_MARKER, DEFAULT_HIGHLIGHT_POST_TAG, DEFAULT_HIGHLIGHT_PRE_TAG,
+    DEFAULT_CROP_LENGTH, DEFAULT_CROP_MARKER, DEFAULT_HIGHLIGHT_POST_TAG,
-    DEFAULT_SEARCH_LIMIT, DEFAULT_SEARCH_OFFSET,
+    DEFAULT_HIGHLIGHT_PRE_TAG, DEFAULT_SEARCH_LIMIT, DEFAULT_SEARCH_OFFSET, DEFAULT_SEMANTIC_RATIO,
 };
 
 pub fn configure(cfg: &mut web::ServiceConfig) {
@@ -74,6 +76,31 @@ pub struct SearchQueryGet {
     matching_strategy: MatchingStrategy,
     #[deserr(default, error = DeserrQueryParamError<InvalidSearchAttributesToSearchOn>)]
     pub attributes_to_search_on: Option<CS<String>>,
+    #[deserr(default, error = DeserrQueryParamError<InvalidEmbedder>)]
+    pub hybrid_embedder: Option<String>,
+    #[deserr(default, error = DeserrQueryParamError<InvalidSearchSemanticRatio>)]
+    pub hybrid_semantic_ratio: Option<SemanticRatioGet>,
+}
+
+#[derive(Debug, Clone, Copy, Default, PartialEq, deserr::Deserr)]
+#[deserr(try_from(String) = TryFrom::try_from -> InvalidSearchSemanticRatio)]
+pub struct SemanticRatioGet(SemanticRatio);
+
+impl std::convert::TryFrom<String> for SemanticRatioGet {
+    type Error = InvalidSearchSemanticRatio;
+
+    fn try_from(s: String) -> Result<Self, Self::Error> {
+        let f: f32 = s.parse().map_err(|_| InvalidSearchSemanticRatio)?;
+        Ok(SemanticRatioGet(SemanticRatio::try_from(f)?))
+    }
+}
+
+impl std::ops::Deref for SemanticRatioGet {
+    type Target = SemanticRatio;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
 }
 
 impl From<SearchQueryGet> for SearchQuery {
@@ -86,6 +113,20 @@ impl From<SearchQueryGet> for SearchQuery {
             None => None,
         };
 
+        let hybrid = match (other.hybrid_embedder, other.hybrid_semantic_ratio) {
+            (None, None) => None,
+            (None, Some(semantic_ratio)) => {
+                Some(HybridQuery { semantic_ratio: *semantic_ratio, embedder: None })
+            }
+            (Some(embedder), None) => Some(HybridQuery {
+                semantic_ratio: DEFAULT_SEMANTIC_RATIO(),
+                embedder: Some(embedder),
+            }),
+            (Some(embedder), Some(semantic_ratio)) => {
+                Some(HybridQuery { semantic_ratio: *semantic_ratio, embedder: Some(embedder) })
+            }
+        };
+
         Self {
             q: other.q,
             vector: other.vector.map(CS::into_inner),
@@ -108,6 +149,7 @@ impl From<SearchQueryGet> for SearchQuery {
             crop_marker: other.crop_marker,
             matching_strategy: other.matching_strategy,
             attributes_to_search_on: other.attributes_to_search_on.map(|o| o.into_iter().collect()),
+            hybrid,
         }
     }
 }
@@ -158,8 +200,12 @@ pub async fn search_with_url_query(
 
     let index = index_scheduler.index(&index_uid)?;
     let features = index_scheduler.features();
+
+    let distribution = embed(&mut query, index_scheduler.get_ref(), &index).await?;
+
     let search_result =
-        tokio::task::spawn_blocking(move || perform_search(&index, query, features)).await?;
+        tokio::task::spawn_blocking(move || perform_search(&index, query, features, distribution))
+            .await?;
     if let Ok(ref search_result) = search_result {
         aggregate.succeed(search_result);
     }
@@ -193,8 +239,12 @@ pub async fn search_with_post(
     let index = index_scheduler.index(&index_uid)?;
 
     let features = index_scheduler.features();
+
+    let distribution = embed(&mut query, index_scheduler.get_ref(), &index).await?;
+
     let search_result =
-        tokio::task::spawn_blocking(move || perform_search(&index, query, features)).await?;
+        tokio::task::spawn_blocking(move || perform_search(&index, query, features, distribution))
+            .await?;
     if let Ok(ref search_result) = search_result {
         aggregate.succeed(search_result);
     }
@@ -206,6 +256,80 @@ pub async fn search_with_post(
     Ok(HttpResponse::Ok().json(search_result))
 }
 
+pub async fn embed(
+    query: &mut SearchQuery,
+    index_scheduler: &IndexScheduler,
+    index: &milli::Index,
+) -> Result<Option<DistributionShift>, ResponseError> {
+    match (&query.hybrid, &query.vector, &query.q) {
+        (Some(HybridQuery { semantic_ratio: _, embedder }), None, Some(q))
+            if !q.trim().is_empty() =>
+        {
+            let embedder_configs = index.embedding_configs(&index.read_txn()?)?;
+            let embedders = index_scheduler.embedders(embedder_configs)?;
+
+            let embedder = if let Some(embedder_name) = embedder {
+                embedders.get(embedder_name)
+            } else {
+                embedders.get_default()
+            };
+
+            let embedder = embedder
+                .ok_or(milli::UserError::InvalidEmbedder("default".to_owned()))
+                .map_err(milli::Error::from)?
+                .0;
+
+            let distribution = embedder.distribution();
+
+            let embeddings = embedder
+                .embed(vec![q.to_owned()])
+                .await
+                .map_err(milli::vector::Error::from)
+                .map_err(milli::Error::from)?
+                .pop()
+                .expect("No vector returned from embedding");
+
+            if embeddings.iter().nth(1).is_some() {
+                warn!("Ignoring embeddings past the first one in long search query");
+                query.vector = Some(embeddings.iter().next().unwrap().to_vec());
+            } else {
+                query.vector = Some(embeddings.into_inner());
+            }
+            Ok(distribution)
+        }
+        (Some(hybrid), vector, _) => {
+            let embedder_configs = index.embedding_configs(&index.read_txn()?)?;
+            let embedders = index_scheduler.embedders(embedder_configs)?;
+
+            let embedder = if let Some(embedder_name) = &hybrid.embedder {
+                embedders.get(embedder_name)
+            } else {
+                embedders.get_default()
+            };
+
+            let embedder = embedder
+                .ok_or(milli::UserError::InvalidEmbedder("default".to_owned()))
+                .map_err(milli::Error::from)?
+                .0;
+
+            if let Some(vector) = vector {
+                if vector.len() != embedder.dimensions() {
+                    return Err(meilisearch_types::milli::Error::UserError(
+                        meilisearch_types::milli::UserError::InvalidVectorDimensions {
+                            expected: embedder.dimensions(),
+                            found: vector.len(),
+                        },
+                    )
+                    .into());
+                }
+            }
+
+            Ok(embedder.distribution())
+        }
+        _ => Ok(None),
+    }
+}
+
 #[cfg(test)]
 mod test {
     use super::*;

meilisearch/src/routes/indexes/settings.rs

@@ -7,6 +7,7 @@ use meilisearch_types::deserr::DeserrJsonError;
 use meilisearch_types::error::ResponseError;
 use meilisearch_types::facet_values_sort::FacetValuesSort;
 use meilisearch_types::index_uid::IndexUid;
+use meilisearch_types::milli::update::Setting;
 use meilisearch_types::settings::{settings, RankingRuleView, Settings, Unchecked};
 use meilisearch_types::tasks::KindWithContent;
 use serde_json::json;
@@ -545,6 +546,67 @@ make_setting_route!(
     }
 );
 
+make_setting_route!(
+    "/embedders",
+    patch,
+    std::collections::BTreeMap<String, Setting<meilisearch_types::milli::vector::settings::EmbeddingSettings>>,
+    meilisearch_types::deserr::DeserrJsonError<
+        meilisearch_types::error::deserr_codes::InvalidSettingsEmbedders,
+    >,
+    embedders,
+    "embedders",
+    analytics,
+    |setting: &Option<std::collections::BTreeMap<String, Setting<meilisearch_types::milli::vector::settings::EmbeddingSettings>>>, req: &HttpRequest| {
+
+
+        analytics.publish(
+            "Embedders Updated".to_string(),
+            serde_json::json!({"embedders": crate::routes::indexes::settings::embedder_analytics(setting.as_ref())}),
+            Some(req),
+        );
+    }
+);
+
+fn embedder_analytics(
+    setting: Option<
+        &std::collections::BTreeMap<
+            String,
+            Setting<meilisearch_types::milli::vector::settings::EmbeddingSettings>,
+        >,
+    >,
+) -> serde_json::Value {
+    let mut sources = std::collections::HashSet::new();
+
+    if let Some(s) = &setting {
+        for source in s
+            .values()
+            .filter_map(|config| config.clone().set())
+            .filter_map(|config| config.embedder_options.set())
+        {
+            use meilisearch_types::milli::vector::settings::EmbedderSettings;
+            match source {
+                EmbedderSettings::OpenAi(_) => sources.insert("openAi"),
+                EmbedderSettings::HuggingFace(_) => sources.insert("huggingFace"),
+                EmbedderSettings::UserProvided(_) => sources.insert("userProvided"),
+            };
+        }
+    };
+
+    let document_template_used = setting.as_ref().map(|map| {
+        map.values()
+            .filter_map(|config| config.clone().set())
+            .any(|config| config.document_template.set().is_some())
+    });
+
+    json!(
+        {
+            "total": setting.as_ref().map(|s| s.len()),
+            "sources": sources,
+            "document_template_used": document_template_used,
+        }
+    )
+}
+
 macro_rules! generate_configure {
     ($($mod:ident),*) => {
         pub fn configure(cfg: &mut web::ServiceConfig) {
@@ -574,7 +636,8 @@ generate_configure!(
     ranking_rules,
     typo_tolerance,
     pagination,
-    faceting
+    faceting,
+    embedders
 );
 
 pub async fn update_all(
@@ -681,6 +744,7 @@ pub async fn update_all(
             "synonyms": {
                 "total": new_settings.synonyms.as_ref().set().map(|synonyms| synonyms.len()),
             },
+            "embedders": crate::routes::indexes::settings::embedder_analytics(new_settings.embedders.as_ref().set())
         }),
         Some(&req),
     );

meilisearch/src/routes/multi_search.rs

@@ -13,6 +13,7 @@ use crate::analytics::{Analytics, MultiSearchAggregator};
 use crate::extractors::authentication::policies::ActionPolicy;
 use crate::extractors::authentication::{AuthenticationError, GuardedData};
 use crate::extractors::sequential_extractor::SeqHandler;
+use crate::routes::indexes::search::embed;
 use crate::search::{
     add_search_rules, perform_search, SearchQueryWithIndex, SearchResultWithIndex,
 };
@@ -74,10 +75,15 @@ pub async fn multi_search_with_post(
                 })
                 .with_index(query_index)?;
 
-            let search_result =
+            let distribution = embed(&mut query, index_scheduler.get_ref(), &index)
-                tokio::task::spawn_blocking(move || perform_search(&index, query, features))
+                .await
-                    .await
+                .with_index(query_index)?;
-                    .with_index(query_index)?;
+
+            let search_result = tokio::task::spawn_blocking(move || {
+                perform_search(&index, query, features, distribution)
+            })
+            .await
+            .with_index(query_index)?;
 
             search_results.push(SearchResultWithIndex {
                 index_uid: index_uid.into_inner(),

meilisearch/src/search.rs

@@ -7,24 +7,21 @@ use deserr::Deserr;
 use either::Either;
 use index_scheduler::RoFeatures;
 use indexmap::IndexMap;
-use log::warn;
 use meilisearch_auth::IndexSearchRules;
 use meilisearch_types::deserr::DeserrJsonError;
 use meilisearch_types::error::deserr_codes::*;
 use meilisearch_types::heed::RoTxn;
 use meilisearch_types::index_uid::IndexUid;
-use meilisearch_types::milli::score_details::{ScoreDetails, ScoringStrategy};
+use meilisearch_types::milli::score_details::{self, ScoreDetails, ScoringStrategy};
-use meilisearch_types::milli::{
+use meilisearch_types::milli::vector::DistributionShift;
-    dot_product_similarity, FacetValueHit, InternalError, OrderBy, SearchForFacetValues,
+use meilisearch_types::milli::{FacetValueHit, OrderBy, SearchForFacetValues};
-};
 use meilisearch_types::settings::DEFAULT_PAGINATION_MAX_TOTAL_HITS;
 use meilisearch_types::{milli, Document};
 use milli::tokenizer::TokenizerBuilder;
 use milli::{
     AscDesc, FieldId, FieldsIdsMap, Filter, FormatOptions, Index, MatchBounds, MatcherBuilder,
-    SortError, TermsMatchingStrategy, VectorOrArrayOfVectors, DEFAULT_VALUES_PER_FACET,
+    SortError, TermsMatchingStrategy, DEFAULT_VALUES_PER_FACET,
 };
-use ordered_float::OrderedFloat;
 use regex::Regex;
 use serde::Serialize;
 use serde_json::{json, Value};
@@ -39,6 +36,7 @@ pub const DEFAULT_CROP_LENGTH: fn() -> usize = || 10;
 pub const DEFAULT_CROP_MARKER: fn() -> String = || "…".to_string();
 pub const DEFAULT_HIGHLIGHT_PRE_TAG: fn() -> String = || "<em>".to_string();
 pub const DEFAULT_HIGHLIGHT_POST_TAG: fn() -> String = || "</em>".to_string();
+pub const DEFAULT_SEMANTIC_RATIO: fn() -> SemanticRatio = || SemanticRatio(0.5);
 
 #[derive(Debug, Clone, Default, PartialEq, Deserr)]
 #[deserr(error = DeserrJsonError, rename_all = camelCase, deny_unknown_fields)]
@@ -47,6 +45,8 @@ pub struct SearchQuery {
     pub q: Option<String>,
     #[deserr(default, error = DeserrJsonError<InvalidSearchVector>)]
     pub vector: Option<Vec<f32>>,
+    #[deserr(default, error = DeserrJsonError<InvalidHybridQuery>)]
+    pub hybrid: Option<HybridQuery>,
     #[deserr(default = DEFAULT_SEARCH_OFFSET(), error = DeserrJsonError<InvalidSearchOffset>)]
     pub offset: usize,
     #[deserr(default = DEFAULT_SEARCH_LIMIT(), error = DeserrJsonError<InvalidSearchLimit>)]
@@ -87,6 +87,48 @@ pub struct SearchQuery {
     pub attributes_to_search_on: Option<Vec<String>>,
 }
 
+#[derive(Debug, Clone, Default, PartialEq, Deserr)]
+#[deserr(error = DeserrJsonError<InvalidHybridQuery>, rename_all = camelCase, deny_unknown_fields)]
+pub struct HybridQuery {
+    /// TODO validate that sementic ratio is between 0.0 and 1,0
+    #[deserr(default, error = DeserrJsonError<InvalidSearchSemanticRatio>, default)]
+    pub semantic_ratio: SemanticRatio,
+    #[deserr(default, error = DeserrJsonError<InvalidEmbedder>, default)]
+    pub embedder: Option<String>,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Deserr)]
+#[deserr(try_from(f32) = TryFrom::try_from -> InvalidSearchSemanticRatio)]
+pub struct SemanticRatio(f32);
+
+impl Default for SemanticRatio {
+    fn default() -> Self {
+        DEFAULT_SEMANTIC_RATIO()
+    }
+}
+
+impl std::convert::TryFrom<f32> for SemanticRatio {
+    type Error = InvalidSearchSemanticRatio;
+
+    fn try_from(f: f32) -> Result<Self, Self::Error> {
+        // the suggested "fix" is: `!(0.0..=1.0).contains(&f)`` which is allegedly less readable
+        #[allow(clippy::manual_range_contains)]
+        if f > 1.0 || f < 0.0 {
+            Err(InvalidSearchSemanticRatio)
+        } else {
+            Ok(SemanticRatio(f))
+        }
+    }
+}
+
+impl std::ops::Deref for SemanticRatio {
+    type Target = f32;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
 impl SearchQuery {
     pub fn is_finite_pagination(&self) -> bool {
         self.page.or(self.hits_per_page).is_some()
@@ -106,6 +148,8 @@ pub struct SearchQueryWithIndex {
     pub q: Option<String>,
     #[deserr(default, error = DeserrJsonError<InvalidSearchQ>)]
     pub vector: Option<Vec<f32>>,
+    #[deserr(default, error = DeserrJsonError<InvalidHybridQuery>)]
+    pub hybrid: Option<HybridQuery>,
     #[deserr(default = DEFAULT_SEARCH_OFFSET(), error = DeserrJsonError<InvalidSearchOffset>)]
     pub offset: usize,
     #[deserr(default = DEFAULT_SEARCH_LIMIT(), error = DeserrJsonError<InvalidSearchLimit>)]
@@ -171,6 +215,7 @@ impl SearchQueryWithIndex {
             crop_marker,
             matching_strategy,
             attributes_to_search_on,
+            hybrid,
         } = self;
         (
             index_uid,
@@ -196,6 +241,7 @@ impl SearchQueryWithIndex {
                 crop_marker,
                 matching_strategy,
                 attributes_to_search_on,
+                hybrid,
                 // do not use ..Default::default() here,
                 // rather add any missing field from `SearchQuery` to `SearchQueryWithIndex`
             },
@@ -335,19 +381,44 @@ fn prepare_search<'t>(
     rtxn: &'t RoTxn,
     query: &'t SearchQuery,
     features: RoFeatures,
+    distribution: Option<DistributionShift>,
 ) -> Result<(milli::Search<'t>, bool, usize, usize), MeilisearchHttpError> {
     let mut search = index.search(rtxn);
 
-    if query.vector.is_some() && query.q.is_some() {
+    if query.vector.is_some() {
-        warn!("Ignoring the query string `q` when used with the `vector` parameter.");
+        features.check_vector("Passing `vector` as a query parameter")?;
     }
 
+    if query.hybrid.is_some() {
+        features.check_vector("Passing `hybrid` as a query parameter")?;
+    }
+
+    if query.hybrid.is_none() && query.q.is_some() && query.vector.is_some() {
+        return Err(MeilisearchHttpError::MissingSearchHybrid);
+    }
+
+    search.distribution_shift(distribution);
+
     if let Some(ref vector) = query.vector {
-        search.vector(vector.clone());
+        match &query.hybrid {
+            // If semantic ratio is 0.0, only the query search will impact the search results,
+            // skip the vector
+            Some(hybrid) if *hybrid.semantic_ratio == 0.0 => (),
+            _otherwise => {
+                search.vector(vector.clone());
+            }
+        }
     }
 
-    if let Some(ref query) = query.q {
+    if let Some(ref q) = query.q {
-        search.query(query);
+        match &query.hybrid {
+            // If semantic ratio is 1.0, only the vector search will impact the search results,
+            // skip the query
+            Some(hybrid) if *hybrid.semantic_ratio == 1.0 => (),
+            _otherwise => {
+                search.query(q);
+            }
+        }
     }
 
     if let Some(ref searchable) = query.attributes_to_search_on {
@@ -374,8 +445,8 @@ fn prepare_search<'t>(
         features.check_score_details()?;
     }
 
-    if query.vector.is_some() {
+    if let Some(HybridQuery { embedder: Some(embedder), .. }) = &query.hybrid {
-        features.check_vector()?;
+        search.embedder_name(embedder);
     }
 
     // compute the offset on the limit depending on the pagination mode.
@@ -421,15 +492,22 @@ pub fn perform_search(
     index: &Index,
     query: SearchQuery,
     features: RoFeatures,
+    distribution: Option<DistributionShift>,
 ) -> Result<SearchResult, MeilisearchHttpError> {
     let before_search = Instant::now();
     let rtxn = index.read_txn()?;
 
     let (search, is_finite_pagination, max_total_hits, offset) =
-        prepare_search(index, &rtxn, &query, features)?;
+        prepare_search(index, &rtxn, &query, features, distribution)?;
 
     let milli::SearchResult { documents_ids, matching_words, candidates, document_scores, .. } =
-        search.execute()?;
+        match &query.hybrid {
+            Some(hybrid) => match *hybrid.semantic_ratio {
+                ratio if ratio == 0.0 || ratio == 1.0 => search.execute()?,
+                ratio => search.execute_hybrid(ratio)?,
+            },
+            None => search.execute()?,
+        };
 
     let fields_ids_map = index.fields_ids_map(&rtxn).unwrap();
 
@@ -538,13 +616,17 @@ pub fn perform_search(
             insert_geo_distance(sort, &mut document);
         }
 
-        let semantic_score = match query.vector.as_ref() {
+        let mut semantic_score = None;
-            Some(vector) => match extract_field("_vectors", &fields_ids_map, obkv)? {
+        for details in &score {
-                Some(vectors) => compute_semantic_score(vector, vectors)?,
+            if let ScoreDetails::Vector(score_details::Vector {
-                None => None,
+                target_vector: _,
-            },
+                value_similarity: Some((_matching_vector, similarity)),
-            None => None,
+            }) = details
-        };
+            {
+                semantic_score = Some(*similarity);
+                break;
+            }
+        }
 
         let ranking_score =
             query.show_ranking_score.then(|| ScoreDetails::global_score(score.iter()));
@@ -647,8 +729,9 @@ pub fn perform_facet_search(
     let before_search = Instant::now();
     let rtxn = index.read_txn()?;
 
-    let (search, _, _, _) = prepare_search(index, &rtxn, &search_query, features)?;
+    let (search, _, _, _) = prepare_search(index, &rtxn, &search_query, features, None)?;
-    let mut facet_search = SearchForFacetValues::new(facet_name, search);
+    let mut facet_search =
+        SearchForFacetValues::new(facet_name, search, search_query.hybrid.is_some());
     if let Some(facet_query) = &facet_query {
         facet_search.query(facet_query);
     }
@@ -676,18 +759,6 @@ fn insert_geo_distance(sorts: &[String], document: &mut Document) {
     }
 }
 
-fn compute_semantic_score(query: &[f32], vectors: Value) -> milli::Result<Option<f32>> {
-    let vectors = serde_json::from_value(vectors)
-        .map(VectorOrArrayOfVectors::into_array_of_vectors)
-        .map_err(InternalError::SerdeJson)?;
-    Ok(vectors
-        .into_iter()
-        .flatten()
-        .map(|v| OrderedFloat(dot_product_similarity(query, &v)))
-        .max()
-        .map(OrderedFloat::into_inner))
-}
-
 fn compute_formatted_options(
     attr_to_highlight: &HashSet<String>,
     attr_to_crop: &[String],
@@ -815,22 +886,6 @@ fn make_document(
     Ok(document)
 }
 
-/// Extract the JSON value under the field name specified
-/// but doesn't support nested objects.
-fn extract_field(
-    field_name: &str,
-    field_ids_map: &FieldsIdsMap,
-    obkv: obkv::KvReaderU16,
-) -> Result<Option<serde_json::Value>, MeilisearchHttpError> {
-    match field_ids_map.id(field_name) {
-        Some(fid) => match obkv.get(fid) {
-            Some(value) => Ok(serde_json::from_slice(value).map(Some)?),
-            None => Ok(None),
-        },
-        None => Ok(None),
-    }
-}
-
 fn format_fields<'a>(
     document: &Document,
     field_ids_map: &FieldsIdsMap,

meilisearch/tests/dumps/mod.rs

@@ -77,7 +77,8 @@ async fn import_dump_v1_movie_raw() {
       },
       "pagination": {
         "maxTotalHits": 1000
-      }
+      },
+      "embedders": {}
     }
     "###
     );
@@ -238,7 +239,8 @@ async fn import_dump_v1_movie_with_settings() {
       },
       "pagination": {
         "maxTotalHits": 1000
-      }
+      },
+      "embedders": {}
     }
     "###
     );
@@ -385,7 +387,8 @@ async fn import_dump_v1_rubygems_with_settings() {
       },
       "pagination": {
         "maxTotalHits": 1000
-      }
+      },
+      "embedders": {}
     }
     "###
     );
@@ -518,7 +521,8 @@ async fn import_dump_v2_movie_raw() {
       },
       "pagination": {
         "maxTotalHits": 1000
-      }
+      },
+      "embedders": {}
     }
     "###
     );
@@ -663,7 +667,8 @@ async fn import_dump_v2_movie_with_settings() {
       },
       "pagination": {
         "maxTotalHits": 1000
-      }
+      },
+      "embedders": {}
     }
     "###
     );
@@ -807,7 +812,8 @@ async fn import_dump_v2_rubygems_with_settings() {
       },
       "pagination": {
         "maxTotalHits": 1000
-      }
+      },
+      "embedders": {}
     }
     "###
     );
@@ -940,7 +946,8 @@ async fn import_dump_v3_movie_raw() {
       },
       "pagination": {
         "maxTotalHits": 1000
-      }
+      },
+      "embedders": {}
     }
     "###
     );
@@ -1085,7 +1092,8 @@ async fn import_dump_v3_movie_with_settings() {
       },
       "pagination": {
         "maxTotalHits": 1000
-      }
+      },
+      "embedders": {}
     }
     "###
     );
@@ -1229,7 +1237,8 @@ async fn import_dump_v3_rubygems_with_settings() {
       },
       "pagination": {
         "maxTotalHits": 1000
-      }
+      },
+      "embedders": {}
     }
     "###
     );
@@ -1362,7 +1371,8 @@ async fn import_dump_v4_movie_raw() {
       },
       "pagination": {
         "maxTotalHits": 1000
-      }
+      },
+      "embedders": {}
     }
     "###
     );
@@ -1507,7 +1517,8 @@ async fn import_dump_v4_movie_with_settings() {
       },
       "pagination": {
         "maxTotalHits": 1000
-      }
+      },
+      "embedders": {}
     }
     "###
     );
@@ -1651,7 +1662,8 @@ async fn import_dump_v4_rubygems_with_settings() {
       },
       "pagination": {
         "maxTotalHits": 1000
-      }
+      },
+      "embedders": {}
     }
     "###
     );
@@ -1896,7 +1908,8 @@ async fn import_dump_v6_containing_experimental_features() {
       },
       "pagination": {
         "maxTotalHits": 1000
-      }
+      },
+      "embedders": {}
     }
     "###);
 

meilisearch/tests/search/hybrid.rs

@@ -0,0 +1,152 @@
+use meili_snap::snapshot;
+use once_cell::sync::Lazy;
+
+use crate::common::index::Index;
+use crate::common::{Server, Value};
+use crate::json;
+
+async fn index_with_documents<'a>(server: &'a Server, documents: &Value) -> Index<'a> {
+    let index = server.index("test");
+
+    let (response, code) = server.set_features(json!({"vectorStore": true})).await;
+
+    meili_snap::snapshot!(code, @"200 OK");
+    meili_snap::snapshot!(meili_snap::json_string!(response), @r###"
+    {
+      "scoreDetails": false,
+      "vectorStore": true,
+      "metrics": false,
+      "exportPuffinReports": false,
+      "proximityPrecision": false
+    }
+    "###);
+
+    let (response, code) = index
+        .update_settings(
+            json!({ "embedders": {"default": {"source": {"userProvided": {"dimensions": 2}}}} }),
+        )
+        .await;
+    assert_eq!(202, code, "{:?}", response);
+    index.wait_task(response.uid()).await;
+
+    let (response, code) = index.add_documents(documents.clone(), None).await;
+    assert_eq!(202, code, "{:?}", response);
+    index.wait_task(response.uid()).await;
+    index
+}
+
+static SIMPLE_SEARCH_DOCUMENTS: Lazy<Value> = Lazy::new(|| {
+    json!([
+    {
+        "title": "Shazam!",
+        "desc": "a Captain Marvel ersatz",
+        "id": "1",
+        "_vectors": {"default": [1.0, 3.0]},
+    },
+    {
+        "title": "Captain Planet",
+        "desc": "He's not part of the Marvel Cinematic Universe",
+        "id": "2",
+        "_vectors": {"default": [1.0, 2.0]},
+    },
+    {
+        "title": "Captain Marvel",
+        "desc": "a Shazam ersatz",
+        "id": "3",
+        "_vectors": {"default": [2.0, 3.0]},
+    }])
+});
+
+#[actix_rt::test]
+async fn simple_search() {
+    let server = Server::new().await;
+    let index = index_with_documents(&server, &SIMPLE_SEARCH_DOCUMENTS).await;
+
+    let (response, code) = index
+        .search_post(
+            json!({"q": "Captain", "vector": [1.0, 1.0], "hybrid": {"semanticRatio": 0.2}}),
+        )
+        .await;
+    snapshot!(code, @"200 OK");
+    snapshot!(response["hits"], @r###"[{"title":"Captain Planet","desc":"He's not part of the Marvel Cinematic Universe","id":"2","_vectors":{"default":[1.0,2.0]}},{"title":"Captain Marvel","desc":"a Shazam ersatz","id":"3","_vectors":{"default":[2.0,3.0]}},{"title":"Shazam!","desc":"a Captain Marvel ersatz","id":"1","_vectors":{"default":[1.0,3.0]}}]"###);
+
+    let (response, code) = index
+        .search_post(
+            json!({"q": "Captain", "vector": [1.0, 1.0], "hybrid": {"semanticRatio": 0.8}}),
+        )
+        .await;
+    snapshot!(code, @"200 OK");
+    snapshot!(response["hits"], @r###"[{"title":"Captain Marvel","desc":"a Shazam ersatz","id":"3","_vectors":{"default":[2.0,3.0]},"_semanticScore":0.99029034},{"title":"Captain Planet","desc":"He's not part of the Marvel Cinematic Universe","id":"2","_vectors":{"default":[1.0,2.0]},"_semanticScore":0.97434163},{"title":"Shazam!","desc":"a Captain Marvel ersatz","id":"1","_vectors":{"default":[1.0,3.0]},"_semanticScore":0.9472136}]"###);
+}
+
+#[actix_rt::test]
+async fn invalid_semantic_ratio() {
+    let server = Server::new().await;
+    let index = index_with_documents(&server, &SIMPLE_SEARCH_DOCUMENTS).await;
+
+    let (response, code) = index
+        .search_post(
+            json!({"q": "Captain", "vector": [1.0, 1.0], "hybrid": {"semanticRatio": 1.2}}),
+        )
+        .await;
+    snapshot!(code, @"400 Bad Request");
+    snapshot!(response, @r###"
+    {
+      "message": "Invalid value at `.hybrid.semanticRatio`: the value of `semanticRatio` is invalid, expected a float between `0.0` and `1.0`.",
+      "code": "invalid_search_semantic_ratio",
+      "type": "invalid_request",
+      "link": "https://docs.meilisearch.com/errors#invalid_search_semantic_ratio"
+    }
+    "###);
+
+    let (response, code) = index
+        .search_post(
+            json!({"q": "Captain", "vector": [1.0, 1.0], "hybrid": {"semanticRatio": -0.8}}),
+        )
+        .await;
+    snapshot!(code, @"400 Bad Request");
+    snapshot!(response, @r###"
+    {
+      "message": "Invalid value at `.hybrid.semanticRatio`: the value of `semanticRatio` is invalid, expected a float between `0.0` and `1.0`.",
+      "code": "invalid_search_semantic_ratio",
+      "type": "invalid_request",
+      "link": "https://docs.meilisearch.com/errors#invalid_search_semantic_ratio"
+    }
+    "###);
+
+    let (response, code) = index
+        .search_get(
+            &yaup::to_string(
+                &json!({"q": "Captain", "vector": [1.0, 1.0], "hybridSemanticRatio": 1.2}),
+            )
+            .unwrap(),
+        )
+        .await;
+    snapshot!(code, @"400 Bad Request");
+    snapshot!(response, @r###"
+    {
+      "message": "Invalid value in parameter `hybridSemanticRatio`: the value of `semanticRatio` is invalid, expected a float between `0.0` and `1.0`.",
+      "code": "invalid_search_semantic_ratio",
+      "type": "invalid_request",
+      "link": "https://docs.meilisearch.com/errors#invalid_search_semantic_ratio"
+    }
+    "###);
+
+    let (response, code) = index
+        .search_get(
+            &yaup::to_string(
+                &json!({"q": "Captain", "vector": [1.0, 1.0], "hybridSemanticRatio": -0.2}),
+            )
+            .unwrap(),
+        )
+        .await;
+    snapshot!(code, @"400 Bad Request");
+    snapshot!(response, @r###"
+    {
+      "message": "Invalid value in parameter `hybridSemanticRatio`: the value of `semanticRatio` is invalid, expected a float between `0.0` and `1.0`.",
+      "code": "invalid_search_semantic_ratio",
+      "type": "invalid_request",
+      "link": "https://docs.meilisearch.com/errors#invalid_search_semantic_ratio"
+    }
+    "###);
+}

meilisearch/tests/search/mod.rs

@@ -6,6 +6,7 @@ mod errors;
 mod facet_search;
 mod formatted;
 mod geo;
+mod hybrid;
 mod multi;
 mod pagination;
 mod restrict_searchable;
@@ -20,22 +21,27 @@ static DOCUMENTS: Lazy<Value> = Lazy::new(|| {
         {
             "title": "Shazam!",
             "id": "287947",
+            "_vectors": { "manual": [1, 2, 3]},
         },
         {
             "title": "Captain Marvel",
             "id": "299537",
+            "_vectors": { "manual": [1, 2, 54] },
         },
         {
             "title": "Escape Room",
             "id": "522681",
+            "_vectors": { "manual": [10, -23, 32] },
         },
         {
             "title": "How to Train Your Dragon: The Hidden World",
             "id": "166428",
+            "_vectors": { "manual": [-100, 231, 32] },
         },
         {
             "title": "Gläss",
             "id": "450465",
+            "_vectors": { "manual": [-100, 340, 90] },
         }
     ])
 });
@@ -57,6 +63,7 @@ static NESTED_DOCUMENTS: Lazy<Value> = Lazy::new(|| {
                 },
             ],
             "cattos": "pésti",
+            "_vectors": { "manual": [1, 2, 3]},
         },
         {
             "id": 654,
@@ -69,12 +76,14 @@ static NESTED_DOCUMENTS: Lazy<Value> = Lazy::new(|| {
                 },
             ],
             "cattos": ["simba", "pestiféré"],
+            "_vectors": { "manual": [1, 2, 54] },
         },
         {
             "id": 750,
             "father": "romain",
             "mother": "michelle",
             "cattos": ["enigma"],
+            "_vectors": { "manual": [10, 23, 32] },
         },
         {
             "id": 951,
@@ -91,6 +100,7 @@ static NESTED_DOCUMENTS: Lazy<Value> = Lazy::new(|| {
                 },
             ],
             "cattos": ["moumoute", "gomez"],
+            "_vectors": { "manual": [10, 23, 32] },
         },
     ])
 });
@@ -802,6 +812,13 @@ async fn experimental_feature_score_details() {
                   {
                     "title": "How to Train Your Dragon: The Hidden World",
                     "id": "166428",
+                    "_vectors": {
+                      "manual": [
+                        -100,
+                        231,
+                        32
+                      ]
+                    },
                     "_rankingScoreDetails": {
                       "words": {
                         "order": 0,
@@ -823,7 +840,7 @@ async fn experimental_feature_score_details() {
                         "order": 3,
                         "attributeRankingOrderScore": 1.0,
                         "queryWordDistanceScore": 0.8095238095238095,
-                        "score": 0.9365079365079364
+                        "score": 0.9727891156462584
                       },
                       "exactness": {
                         "order": 4,
@@ -870,13 +887,92 @@ async fn experimental_feature_vector_store() {
     meili_snap::snapshot!(code, @"200 OK");
     meili_snap::snapshot!(response["vectorStore"], @"true");
 
+    let (response, code) = index
+        .update_settings(json!({"embedders": {
+            "manual": {
+                "source": {
+                    "userProvided": {"dimensions": 3}
+                }
+            }
+        }}))
+        .await;
+
+    meili_snap::snapshot!(code, @"202 Accepted");
+    let response = index.wait_task(response.uid()).await;
+
+    meili_snap::snapshot!(meili_snap::json_string!(response["status"]), @"\"succeeded\"");
+
     let (response, code) = index
         .search_post(json!({
             "vector": [1.0, 2.0, 3.0],
         }))
         .await;
+
     meili_snap::snapshot!(code, @"200 OK");
-    meili_snap::snapshot!(meili_snap::json_string!(response["hits"]), @"[]");
+    // vector search returns all documents that don't have vectors in the last bucket, like all sorts
+    meili_snap::snapshot!(meili_snap::json_string!(response["hits"]), @r###"
+    [
+      {
+        "title": "Shazam!",
+        "id": "287947",
+        "_vectors": {
+          "manual": [
+            1,
+            2,
+            3
+          ]
+        },
+        "_semanticScore": 1.0
+      },
+      {
+        "title": "Captain Marvel",
+        "id": "299537",
+        "_vectors": {
+          "manual": [
+            1,
+            2,
+            54
+          ]
+        },
+        "_semanticScore": 0.9129112
+      },
+      {
+        "title": "Gläss",
+        "id": "450465",
+        "_vectors": {
+          "manual": [
+            -100,
+            340,
+            90
+          ]
+        },
+        "_semanticScore": 0.8106413
+      },
+      {
+        "title": "How to Train Your Dragon: The Hidden World",
+        "id": "166428",
+        "_vectors": {
+          "manual": [
+            -100,
+            231,
+            32
+          ]
+        },
+        "_semanticScore": 0.74120104
+      },
+      {
+        "title": "Escape Room",
+        "id": "522681",
+        "_vectors": {
+          "manual": [
+            10,
+            -23,
+            32
+          ]
+        }
+      }
+    ]
+    "###);
 }
 
 #[cfg(feature = "default")]
@@ -1126,7 +1222,14 @@ async fn simple_search_with_strange_synonyms() {
             [
               {
                 "title": "How to Train Your Dragon: The Hidden World",
-                "id": "166428"
+                "id": "166428",
+                "_vectors": {
+                  "manual": [
+                    -100,
+                    231,
+                    32
+                  ]
+                }
               }
             ]
             "###);
@@ -1140,7 +1243,14 @@ async fn simple_search_with_strange_synonyms() {
             [
               {
                 "title": "How to Train Your Dragon: The Hidden World",
-                "id": "166428"
+                "id": "166428",
+                "_vectors": {
+                  "manual": [
+                    -100,
+                    231,
+                    32
+                  ]
+                }
               }
             ]
             "###);
@@ -1154,7 +1264,14 @@ async fn simple_search_with_strange_synonyms() {
             [
               {
                 "title": "How to Train Your Dragon: The Hidden World",
-                "id": "166428"
+                "id": "166428",
+                "_vectors": {
+                  "manual": [
+                    -100,
+                    231,
+                    32
+                  ]
+                }
               }
             ]
             "###);

meilisearch/tests/search/multi.rs

@@ -72,7 +72,14 @@ async fn simple_search_single_index() {
         "hits": [
           {
             "title": "Gläss",
-            "id": "450465"
+            "id": "450465",
+            "_vectors": {
+              "manual": [
+                -100,
+                340,
+                90
+              ]
+            }
           }
         ],
         "query": "glass",
@@ -86,7 +93,14 @@ async fn simple_search_single_index() {
         "hits": [
           {
             "title": "Captain Marvel",
-            "id": "299537"
+            "id": "299537",
+            "_vectors": {
+              "manual": [
+                1,
+                2,
+                54
+              ]
+            }
           }
         ],
         "query": "captain",
@@ -177,7 +191,14 @@ async fn simple_search_two_indexes() {
         "hits": [
           {
             "title": "Gläss",
-            "id": "450465"
+            "id": "450465",
+            "_vectors": {
+              "manual": [
+                -100,
+                340,
+                90
+              ]
+            }
           }
         ],
         "query": "glass",
@@ -203,7 +224,14 @@ async fn simple_search_two_indexes() {
                 "age": 4
               }
             ],
-            "cattos": "pésti"
+            "cattos": "pésti",
+            "_vectors": {
+              "manual": [
+                1,
+                2,
+                3
+              ]
+            }
           },
           {
             "id": 654,
@@ -218,7 +246,14 @@ async fn simple_search_two_indexes() {
             "cattos": [
               "simba",
               "pestiféré"
-            ]
+            ],
+            "_vectors": {
+              "manual": [
+                1,
+                2,
+                54
+              ]
+            }
           }
         ],
         "query": "pésti",

meilisearch/tests/settings/get_settings.rs

@@ -54,7 +54,7 @@ async fn get_settings() {
     let (response, code) = index.settings().await;
     assert_eq!(code, 200);
     let settings = response.as_object().unwrap();
-    assert_eq!(settings.keys().len(), 15);
+    assert_eq!(settings.keys().len(), 16);
     assert_eq!(settings["displayedAttributes"], json!(["*"]));
     assert_eq!(settings["searchableAttributes"], json!(["*"]));
     assert_eq!(settings["filterableAttributes"], json!([]));
@@ -83,6 +83,7 @@ async fn get_settings() {
             "maxTotalHits": 1000,
         })
     );
+    assert_eq!(settings["embedders"], json!({}));
 }
 
 #[actix_rt::test]

milli/Cargo.toml

@@ -27,13 +27,15 @@ fst = "0.4.7"
 fxhash = "0.2.1"
 geoutils = "0.5.1"
 grenad = { version = "0.4.5", default-features = false, features = [
-    "rayon", "tempfile"
+    "rayon",
+    "tempfile",
 ] }
 heed = { version = "0.20.0-alpha.9", default-features = false, features = [
-    "serde-json", "serde-bincode", "read-txn-no-tls"
+    "serde-json",
+    "serde-bincode",
+    "read-txn-no-tls",
 ] }
 indexmap = { version = "2.0.0", features = ["serde"] }
-instant-distance = { version = "0.6.1", features = ["with-serde"] }
 json-depth-checker = { path = "../json-depth-checker" }
 levenshtein_automata = { version = "0.2.1", features = ["fst_automaton"] }
 memmap2 = "0.7.1"
@@ -72,6 +74,23 @@ puffin = "0.16.0"
 log = "0.4.17"
 logging_timer = "1.1.0"
 csv = "1.2.1"
+candle-core = { git = "https://github.com/huggingface/candle.git", version = "0.3.1" }
+candle-transformers = { git = "https://github.com/huggingface/candle.git", version = "0.3.1" }
+candle-nn = { git = "https://github.com/huggingface/candle.git", version = "0.3.1" }
+tokenizers = { git = "https://github.com/huggingface/tokenizers.git", tag = "v0.14.1", version = "0.14.1" }
+hf-hub = { git = "https://github.com/dureuill/hf-hub.git", branch = "rust_tls", default_features = false, features = [
+    "online",
+] }
+tokio = { version = "1.34.0", features = ["rt"] }
+futures = "0.3.29"
+reqwest = { version = "0.11.16", features = [
+    "rustls-tls",
+    "json",
+], default-features = false }
+tiktoken-rs = "0.5.7"
+liquid = "0.26.4"
+arroy = { git = "https://github.com/meilisearch/arroy.git", version = "0.1.0" }
+rand = "0.8.5"
 
 [dev-dependencies]
 mimalloc = { version = "0.1.37", default-features = false }
@@ -83,7 +102,15 @@ meili-snap = { path = "../meili-snap" }
 rand = { version = "0.8.5", features = ["small_rng"] }
 
 [features]
-all-tokenizations = ["charabia/chinese", "charabia/hebrew", "charabia/japanese", "charabia/thai", "charabia/korean", "charabia/greek", "charabia/khmer"]
+all-tokenizations = [
+    "charabia/chinese",
+    "charabia/hebrew",
+    "charabia/japanese",
+    "charabia/thai",
+    "charabia/korean",
+    "charabia/greek",
+    "charabia/khmer",
+]
 
 # Use POSIX semaphores instead of SysV semaphores in LMDB
 # For more information on this feature, see heed's Cargo.toml

milli/examples/search.rs

@@ -5,8 +5,8 @@ use std::time::Instant;
 
 use heed::EnvOpenOptions;
 use milli::{
-    execute_search, DefaultSearchLogger, GeoSortStrategy, Index, SearchContext, SearchLogger,
+    execute_search, filtered_universe, DefaultSearchLogger, GeoSortStrategy, Index, SearchContext,
-    TermsMatchingStrategy,
+    SearchLogger, TermsMatchingStrategy,
 };
 
 #[global_allocator]
@@ -49,14 +49,15 @@ fn main() -> Result<(), Box<dyn Error>> {
             let start = Instant::now();
 
             let mut ctx = SearchContext::new(&index, &txn);
+            let universe = filtered_universe(&ctx, &None)?;
+
             let docs = execute_search(
                 &mut ctx,
-                &(!query.trim().is_empty()).then(|| query.trim().to_owned()),
+                (!query.trim().is_empty()).then(|| query.trim()),
-                &None,
                 TermsMatchingStrategy::Last,
                 milli::score_details::ScoringStrategy::Skip,
                 false,
-                &None,
+                universe,
                 &None,
                 GeoSortStrategy::default(),
                 0,

milli/src/distance.rs

@@ -1,41 +0,0 @@
-use std::ops;
-
-use instant_distance::Point;
-use serde::{Deserialize, Serialize};
-
-use crate::normalize_vector;
-
-#[derive(Debug, Default, Clone, Serialize, Deserialize)]
-pub struct NDotProductPoint(Vec<f32>);
-
-impl NDotProductPoint {
-    pub fn new(point: Vec<f32>) -> Self {
-        NDotProductPoint(normalize_vector(point))
-    }
-
-    pub fn into_inner(self) -> Vec<f32> {
-        self.0
-    }
-}
-
-impl ops::Deref for NDotProductPoint {
-    type Target = [f32];
-
-    fn deref(&self) -> &Self::Target {
-        self.0.as_slice()
-    }
-}
-
-impl Point for NDotProductPoint {
-    fn distance(&self, other: &Self) -> f32 {
-        let dist = 1.0 - dot_product_similarity(&self.0, &other.0);
-        debug_assert!(!dist.is_nan());
-        dist
-    }
-}
-
-/// Returns the dot product similarity score that will between 0.0 and 1.0
-/// if both vectors are normalized. The higher the more similar the vectors are.
-pub fn dot_product_similarity(a: &[f32], b: &[f32]) -> f32 {
-    a.iter().zip(b).map(|(a, b)| a * b).sum()
-}

milli/src/error.rs

@@ -61,6 +61,10 @@ pub enum InternalError {
     AbortedIndexation,
     #[error("The matching words list contains at least one invalid member.")]
     InvalidMatchingWords,
+    #[error(transparent)]
+    ArroyError(#[from] arroy::Error),
+    #[error(transparent)]
+    VectorEmbeddingError(#[from] crate::vector::Error),
 }
 
 #[derive(Error, Debug)]
@@ -110,8 +114,10 @@ only composed of alphanumeric characters (a-z A-Z 0-9), hyphens (-) and undersco
     InvalidGeoField(#[from] GeoError),
     #[error("Invalid vector dimensions: expected: `{}`, found: `{}`.", .expected, .found)]
     InvalidVectorDimensions { expected: usize, found: usize },
-    #[error("The `_vectors` field in the document with the id: `{document_id}` is not an array. Was expecting an array of floats or an array of arrays of floats but instead got `{value}`.")]
+    #[error("The `_vectors.{subfield}` field in the document with id: `{document_id}` is not an array. Was expecting an array of floats or an array of arrays of floats but instead got `{value}`.")]
-    InvalidVectorsType { document_id: Value, value: Value },
+    InvalidVectorsType { document_id: Value, value: Value, subfield: String },
+    #[error("The `_vectors` field in the document with id: `{document_id}` is not an object. Was expecting an object with a key for each embedder with manually provided vectors, but instead got `{value}`")]
+    InvalidVectorsMapType { document_id: Value, value: Value },
     #[error("{0}")]
     InvalidFilter(String),
     #[error("Invalid type for filter subexpression: expected: {}, found: {1}.", .0.join(", "))]
@@ -180,6 +186,49 @@ only composed of alphanumeric characters (a-z A-Z 0-9), hyphens (-) and undersco
     UnknownInternalDocumentId { document_id: DocumentId },
     #[error("`minWordSizeForTypos` setting is invalid. `oneTypo` and `twoTypos` fields should be between `0` and `255`, and `twoTypos` should be greater or equals to `oneTypo` but found `oneTypo: {0}` and twoTypos: {1}`.")]
     InvalidMinTypoWordLenSetting(u8, u8),
+    #[error(transparent)]
+    VectorEmbeddingError(#[from] crate::vector::Error),
+    #[error(transparent)]
+    MissingDocumentField(#[from] crate::prompt::error::RenderPromptError),
+    #[error(transparent)]
+    InvalidPrompt(#[from] crate::prompt::error::NewPromptError),
+    #[error("Invalid prompt in for embeddings with name '{0}': {1}.")]
+    InvalidPromptForEmbeddings(String, crate::prompt::error::NewPromptError),
+    #[error("Too many embedders in the configuration. Found {0}, but limited to 256.")]
+    TooManyEmbedders(usize),
+    #[error("Cannot find embedder with name {0}.")]
+    InvalidEmbedder(String),
+    #[error("Too many vectors for document with id {0}: found {1}, but limited to 256.")]
+    TooManyVectors(String, usize),
+}
+
+impl From<crate::vector::Error> for Error {
+    fn from(value: crate::vector::Error) -> Self {
+        match value.fault() {
+            FaultSource::User => Error::UserError(value.into()),
+            FaultSource::Runtime => Error::InternalError(value.into()),
+            FaultSource::Bug => Error::InternalError(value.into()),
+            FaultSource::Undecided => Error::InternalError(value.into()),
+        }
+    }
+}
+
+impl From<arroy::Error> for Error {
+    fn from(value: arroy::Error) -> Self {
+        match value {
+            arroy::Error::Heed(heed) => heed.into(),
+            arroy::Error::Io(io) => io.into(),
+            arroy::Error::InvalidVecDimension { expected, received } => {
+                Error::UserError(UserError::InvalidVectorDimensions { expected, found: received })
+            }
+            arroy::Error::DatabaseFull
+            | arroy::Error::InvalidItemAppend
+            | arroy::Error::UnmatchingDistance { .. }
+            | arroy::Error::MissingMetadata => {
+                Error::InternalError(InternalError::ArroyError(value))
+            }
+        }
+    }
 }
 
 #[derive(Error, Debug)]
@@ -336,6 +385,26 @@ impl From<HeedError> for Error {
     }
 }
 
+#[derive(Debug, Clone, Copy)]
+pub enum FaultSource {
+    User,
+    Runtime,
+    Bug,
+    Undecided,
+}
+
+impl std::fmt::Display for FaultSource {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let s = match self {
+            FaultSource::User => "user error",
+            FaultSource::Runtime => "runtime error",
+            FaultSource::Bug => "coding error",
+            FaultSource::Undecided => "error",
+        };
+        f.write_str(s)
+    }
+}
+
 #[test]
 fn conditionally_lookup_for_error_message() {
     let prefix = "Attribute `name` is not sortable.";

milli/src/index.rs

@@ -10,7 +10,6 @@ use roaring::RoaringBitmap;
 use rstar::RTree;
 use time::OffsetDateTime;
 
-use crate::distance::NDotProductPoint;
 use crate::documents::PrimaryKey;
 use crate::error::{InternalError, UserError};
 use crate::fields_ids_map::FieldsIdsMap;
@@ -22,7 +21,7 @@ use crate::heed_codec::{
     BEU16StrCodec, FstSetCodec, ScriptLanguageCodec, StrBEU16Codec, StrRefCodec,
 };
 use crate::proximity::ProximityPrecision;
-use crate::readable_slices::ReadableSlices;
+use crate::vector::EmbeddingConfig;
 use crate::{
     default_criteria, CboRoaringBitmapCodec, Criterion, DocumentId, ExternalDocumentsIds,
     FacetDistribution, FieldDistribution, FieldId, FieldIdWordCountCodec, GeoPoint, ObkvCodec,
@@ -30,9 +29,6 @@ use crate::{
     BEU32, BEU64,
 };
 
-/// The HNSW data-structure that we serialize, fill and search in.
-pub type Hnsw = instant_distance::Hnsw<NDotProductPoint>;
-
 pub const DEFAULT_MIN_WORD_LEN_ONE_TYPO: u8 = 5;
 pub const DEFAULT_MIN_WORD_LEN_TWO_TYPOS: u8 = 9;
 
@@ -48,10 +44,6 @@ pub mod main_key {
     pub const FIELDS_IDS_MAP_KEY: &str = "fields-ids-map";
     pub const GEO_FACETED_DOCUMENTS_IDS_KEY: &str = "geo-faceted-documents-ids";
     pub const GEO_RTREE_KEY: &str = "geo-rtree";
-    /// The prefix of the key that is used to store the, potential big, HNSW structure.
-    /// It is concatenated with a big-endian encoded number (non-human readable).
-    /// e.g. vector-hnsw0x0032.
-    pub const VECTOR_HNSW_KEY_PREFIX: &str = "vector-hnsw";
     pub const PRIMARY_KEY_KEY: &str = "primary-key";
     pub const SEARCHABLE_FIELDS_KEY: &str = "searchable-fields";
     pub const USER_DEFINED_SEARCHABLE_FIELDS_KEY: &str = "user-defined-searchable-fields";
@@ -74,6 +66,7 @@ pub mod main_key {
     pub const SORT_FACET_VALUES_BY: &str = "sort-facet-values-by";
     pub const PAGINATION_MAX_TOTAL_HITS: &str = "pagination-max-total-hits";
     pub const PROXIMITY_PRECISION: &str = "proximity-precision";
+    pub const EMBEDDING_CONFIGS: &str = "embedding_configs";
 }
 
 pub mod db_name {
@@ -99,7 +92,8 @@ pub mod db_name {
     pub const FACET_ID_STRING_FST: &str = "facet-id-string-fst";
     pub const FIELD_ID_DOCID_FACET_F64S: &str = "field-id-docid-facet-f64s";
     pub const FIELD_ID_DOCID_FACET_STRINGS: &str = "field-id-docid-facet-strings";
-    pub const VECTOR_ID_DOCID: &str = "vector-id-docids";
+    pub const VECTOR_EMBEDDER_CATEGORY_ID: &str = "vector-embedder-category-id";
+    pub const VECTOR_ARROY: &str = "vector-arroy";
     pub const DOCUMENTS: &str = "documents";
     pub const SCRIPT_LANGUAGE_DOCIDS: &str = "script_language_docids";
 }
@@ -166,8 +160,10 @@ pub struct Index {
     /// Maps the document id, the facet field id and the strings.
     pub field_id_docid_facet_strings: Database<FieldDocIdFacetStringCodec, Str>,
 
-    /// Maps a vector id to the document id that have it.
+    /// Maps an embedder name to its id in the arroy store.
-    pub vector_id_docid: Database<BEU32, BEU32>,
+    pub embedder_category_id: Database<Str, U8>,
+    /// Vector store based on arroy™.
+    pub vector_arroy: arroy::Database<arroy::distances::Angular>,
 
     /// Maps the document id to the document as an obkv store.
     pub(crate) documents: Database<BEU32, ObkvCodec>,
@@ -182,7 +178,7 @@ impl Index {
     ) -> Result<Index> {
         use db_name::*;
 
-        options.max_dbs(24);
+        options.max_dbs(25);
 
         let env = options.open(path)?;
         let mut wtxn = env.write_txn()?;
@@ -222,7 +218,11 @@ impl Index {
             env.create_database(&mut wtxn, Some(FIELD_ID_DOCID_FACET_F64S))?;
         let field_id_docid_facet_strings =
             env.create_database(&mut wtxn, Some(FIELD_ID_DOCID_FACET_STRINGS))?;
-        let vector_id_docid = env.create_database(&mut wtxn, Some(VECTOR_ID_DOCID))?;
+        // vector stuff
+        let embedder_category_id =
+            env.create_database(&mut wtxn, Some(VECTOR_EMBEDDER_CATEGORY_ID))?;
+        let vector_arroy = env.create_database(&mut wtxn, Some(VECTOR_ARROY))?;
+
         let documents = env.create_database(&mut wtxn, Some(DOCUMENTS))?;
         wtxn.commit()?;
 
@@ -252,7 +252,8 @@ impl Index {
             facet_id_is_empty_docids,
             field_id_docid_facet_f64s,
             field_id_docid_facet_strings,
-            vector_id_docid,
+            vector_arroy,
+            embedder_category_id,
             documents,
         })
     }
@@ -475,63 +476,6 @@ impl Index {
             None => Ok(RoaringBitmap::new()),
         }
     }
-
-    /* vector HNSW */
-
-    /// Writes the provided `hnsw`.
-    pub(crate) fn put_vector_hnsw(&self, wtxn: &mut RwTxn, hnsw: &Hnsw) -> heed::Result<()> {
-        // We must delete all the chunks before we write the new HNSW chunks.
-        self.delete_vector_hnsw(wtxn)?;
-
-        let chunk_size = 1024 * 1024 * (1024 + 512); // 1.5 GiB
-        let bytes = bincode::serialize(hnsw).map_err(Into::into).map_err(heed::Error::Encoding)?;
-        for (i, chunk) in bytes.chunks(chunk_size).enumerate() {
-            let i = i as u32;
-            let mut key = main_key::VECTOR_HNSW_KEY_PREFIX.as_bytes().to_vec();
-            key.extend_from_slice(&i.to_be_bytes());
-            self.main.remap_types::<Bytes, Bytes>().put(wtxn, &key, chunk)?;
-        }
-        Ok(())
-    }
-
-    /// Delete the `hnsw`.
-    pub(crate) fn delete_vector_hnsw(&self, wtxn: &mut RwTxn) -> heed::Result<bool> {
-        let mut iter = self
-            .main
-            .remap_types::<Bytes, DecodeIgnore>()
-            .prefix_iter_mut(wtxn, main_key::VECTOR_HNSW_KEY_PREFIX.as_bytes())?;
-        let mut deleted = false;
-        while iter.next().transpose()?.is_some() {
-            // We do not keep a reference to the key or the value.
-            unsafe { deleted |= iter.del_current()? };
-        }
-        Ok(deleted)
-    }
-
-    /// Returns the `hnsw`.
-    pub fn vector_hnsw(&self, rtxn: &RoTxn) -> Result<Option<Hnsw>> {
-        let mut slices = Vec::new();
-        for result in self
-            .main
-            .remap_types::<Str, Bytes>()
-            .prefix_iter(rtxn, main_key::VECTOR_HNSW_KEY_PREFIX)?
-        {
-            let (_, slice) = result?;
-            slices.push(slice);
-        }
-
-        if slices.is_empty() {
-            Ok(None)
-        } else {
-            let readable_slices: ReadableSlices<_> = slices.into_iter().collect();
-            Ok(Some(
-                bincode::deserialize_from(readable_slices)
-                    .map_err(Into::into)
-                    .map_err(heed::Error::Decoding)?,
-            ))
-        }
-    }
-
     /* field distribution */
 
     /// Writes the field distribution which associates every field name with
@@ -1528,6 +1472,41 @@ impl Index {
 
         Ok(script_language)
     }
+
+    pub(crate) fn put_embedding_configs(
+        &self,
+        wtxn: &mut RwTxn<'_>,
+        configs: Vec<(String, EmbeddingConfig)>,
+    ) -> heed::Result<()> {
+        self.main.remap_types::<Str, SerdeJson<Vec<(String, EmbeddingConfig)>>>().put(
+            wtxn,
+            main_key::EMBEDDING_CONFIGS,
+            &configs,
+        )
+    }
+
+    pub(crate) fn delete_embedding_configs(&self, wtxn: &mut RwTxn<'_>) -> heed::Result<bool> {
+        self.main.remap_key_type::<Str>().delete(wtxn, main_key::EMBEDDING_CONFIGS)
+    }
+
+    pub fn embedding_configs(
+        &self,
+        rtxn: &RoTxn<'_>,
+    ) -> Result<Vec<(String, crate::vector::EmbeddingConfig)>> {
+        Ok(self
+            .main
+            .remap_types::<Str, SerdeJson<Vec<(String, EmbeddingConfig)>>>()
+            .get(rtxn, main_key::EMBEDDING_CONFIGS)?
+            .unwrap_or_default())
+    }
+
+    pub fn default_embedding_name(&self, rtxn: &RoTxn<'_>) -> Result<String> {
+        let configs = self.embedding_configs(rtxn)?;
+        Ok(match configs.as_slice() {
+            [(ref first_name, _)] => first_name.clone(),
+            _ => "default".to_owned(),
+        })
+    }
 }
 
 #[cfg(test)]

milli/src/lib.rs

@@ -10,18 +10,18 @@ pub mod documents;
 
 mod asc_desc;
 mod criterion;
-pub mod distance;
 mod error;
 mod external_documents_ids;
 pub mod facet;
 mod fields_ids_map;
 pub mod heed_codec;
 pub mod index;
+pub mod prompt;
 pub mod proximity;
-mod readable_slices;
 pub mod score_details;
 mod search;
 pub mod update;
+pub mod vector;
 
 #[cfg(test)]
 #[macro_use]
@@ -32,13 +32,12 @@ use std::convert::{TryFrom, TryInto};
 use std::hash::BuildHasherDefault;
 
 use charabia::normalizer::{CharNormalizer, CompatibilityDecompositionNormalizer};
-pub use distance::dot_product_similarity;
 pub use filter_parser::{Condition, FilterCondition, Span, Token};
 use fxhash::{FxHasher32, FxHasher64};
 pub use grenad::CompressionType;
 pub use search::new::{
-    execute_search, DefaultSearchLogger, GeoSortStrategy, SearchContext, SearchLogger,
+    execute_search, filtered_universe, DefaultSearchLogger, GeoSortStrategy, SearchContext,
-    VisualSearchLogger,
+    SearchLogger, VisualSearchLogger,
 };
 use serde_json::Value;
 pub use {charabia as tokenizer, heed};

milli/src/prompt/context.rs

@@ -0,0 +1,97 @@
+use liquid::model::{
+    ArrayView, DisplayCow, KStringCow, ObjectRender, ObjectSource, State, Value as LiquidValue,
+};
+use liquid::{ObjectView, ValueView};
+
+use super::document::Document;
+use super::fields::Fields;
+use crate::FieldsIdsMap;
+
+#[derive(Debug, Clone)]
+pub struct Context<'a> {
+    document: &'a Document<'a>,
+    fields: Fields<'a>,
+}
+
+impl<'a> Context<'a> {
+    pub fn new(document: &'a Document<'a>, field_id_map: &'a FieldsIdsMap) -> Self {
+        Self { document, fields: Fields::new(document, field_id_map) }
+    }
+}
+
+impl<'a> ObjectView for Context<'a> {
+    fn as_value(&self) -> &dyn ValueView {
+        self
+    }
+
+    fn size(&self) -> i64 {
+        2
+    }
+
+    fn keys<'k>(&'k self) -> Box<dyn Iterator<Item = KStringCow<'k>> + 'k> {
+        Box::new(["doc", "fields"].iter().map(|s| KStringCow::from_static(s)))
+    }
+
+    fn values<'k>(&'k self) -> Box<dyn Iterator<Item = &'k dyn ValueView> + 'k> {
+        Box::new(
+            std::iter::once(self.document.as_value())
+                .chain(std::iter::once(self.fields.as_value())),
+        )
+    }
+
+    fn iter<'k>(&'k self) -> Box<dyn Iterator<Item = (KStringCow<'k>, &'k dyn ValueView)> + 'k> {
+        Box::new(self.keys().zip(self.values()))
+    }
+
+    fn contains_key(&self, index: &str) -> bool {
+        index == "doc" || index == "fields"
+    }
+
+    fn get<'s>(&'s self, index: &str) -> Option<&'s dyn ValueView> {
+        match index {
+            "doc" => Some(self.document.as_value()),
+            "fields" => Some(self.fields.as_value()),
+            _ => None,
+        }
+    }
+}
+
+impl<'a> ValueView for Context<'a> {
+    fn as_debug(&self) -> &dyn std::fmt::Debug {
+        self
+    }
+
+    fn render(&self) -> liquid::model::DisplayCow<'_> {
+        DisplayCow::Owned(Box::new(ObjectRender::new(self)))
+    }
+
+    fn source(&self) -> liquid::model::DisplayCow<'_> {
+        DisplayCow::Owned(Box::new(ObjectSource::new(self)))
+    }
+
+    fn type_name(&self) -> &'static str {
+        "object"
+    }
+
+    fn query_state(&self, state: liquid::model::State) -> bool {
+        match state {
+            State::Truthy => true,
+            State::DefaultValue | State::Empty | State::Blank => false,
+        }
+    }
+
+    fn to_kstr(&self) -> liquid::model::KStringCow<'_> {
+        let s = ObjectRender::new(self).to_string();
+        KStringCow::from_string(s)
+    }
+
+    fn to_value(&self) -> LiquidValue {
+        LiquidValue::Object(
+            self.iter().map(|(k, x)| (k.to_string().into(), x.to_value())).collect(),
+        )
+    }
+
+    fn as_object(&self) -> Option<&dyn ObjectView> {
+        Some(self)
+    }
+}

milli/src/prompt/document.rs

@@ -0,0 +1,131 @@
+use std::cell::OnceCell;
+use std::collections::BTreeMap;
+
+use liquid::model::{
+    DisplayCow, KString, KStringCow, ObjectRender, ObjectSource, State, Value as LiquidValue,
+};
+use liquid::{ObjectView, ValueView};
+
+use crate::update::del_add::{DelAdd, KvReaderDelAdd};
+use crate::FieldsIdsMap;
+
+#[derive(Debug, Clone)]
+pub struct Document<'a>(BTreeMap<&'a str, (&'a [u8], ParsedValue)>);
+
+#[derive(Debug, Clone)]
+struct ParsedValue(std::cell::OnceCell<LiquidValue>);
+
+impl ParsedValue {
+    fn empty() -> ParsedValue {
+        ParsedValue(OnceCell::new())
+    }
+
+    fn get(&self, raw: &[u8]) -> &LiquidValue {
+        self.0.get_or_init(|| {
+            let value: serde_json::Value = serde_json::from_slice(raw).unwrap();
+            liquid::model::to_value(&value).unwrap()
+        })
+    }
+}
+
+impl<'a> Document<'a> {
+    pub fn new(
+        data: obkv::KvReaderU16<'a>,
+        side: DelAdd,
+        inverted_field_map: &'a FieldsIdsMap,
+    ) -> Self {
+        let mut out_data = BTreeMap::new();
+        for (fid, raw) in data {
+            let obkv = KvReaderDelAdd::new(raw);
+            let Some(raw) = obkv.get(side) else {
+                continue;
+            };
+            let Some(name) = inverted_field_map.name(fid) else {
+                continue;
+            };
+            out_data.insert(name, (raw, ParsedValue::empty()));
+        }
+        Self(out_data)
+    }
+
+    fn is_empty(&self) -> bool {
+        self.0.is_empty()
+    }
+
+    fn len(&self) -> usize {
+        self.0.len()
+    }
+
+    fn iter(&self) -> impl Iterator<Item = (KString, LiquidValue)> + '_ {
+        self.0.iter().map(|(&k, (raw, data))| (k.to_owned().into(), data.get(raw).to_owned()))
+    }
+}
+
+impl<'a> ObjectView for Document<'a> {
+    fn as_value(&self) -> &dyn ValueView {
+        self
+    }
+
+    fn size(&self) -> i64 {
+        self.len() as i64
+    }
+
+    fn keys<'k>(&'k self) -> Box<dyn Iterator<Item = KStringCow<'k>> + 'k> {
+        let keys = BTreeMap::keys(&self.0).map(|&s| s.into());
+        Box::new(keys)
+    }
+
+    fn values<'k>(&'k self) -> Box<dyn Iterator<Item = &'k dyn ValueView> + 'k> {
+        Box::new(self.0.values().map(|(raw, v)| v.get(raw) as &dyn ValueView))
+    }
+
+    fn iter<'k>(&'k self) -> Box<dyn Iterator<Item = (KStringCow<'k>, &'k dyn ValueView)> + 'k> {
+        Box::new(self.0.iter().map(|(&k, (raw, data))| (k.into(), data.get(raw) as &dyn ValueView)))
+    }
+
+    fn contains_key(&self, index: &str) -> bool {
+        self.0.contains_key(index)
+    }
+
+    fn get<'s>(&'s self, index: &str) -> Option<&'s dyn ValueView> {
+        self.0.get(index).map(|(raw, v)| v.get(raw) as &dyn ValueView)
+    }
+}
+
+impl<'a> ValueView for Document<'a> {
+    fn as_debug(&self) -> &dyn std::fmt::Debug {
+        self
+    }
+
+    fn render(&self) -> liquid::model::DisplayCow<'_> {
+        DisplayCow::Owned(Box::new(ObjectRender::new(self)))
+    }
+
+    fn source(&self) -> liquid::model::DisplayCow<'_> {
+        DisplayCow::Owned(Box::new(ObjectSource::new(self)))
+    }
+
+    fn type_name(&self) -> &'static str {
+        "object"
+    }
+
+    fn query_state(&self, state: liquid::model::State) -> bool {
+        match state {
+            State::Truthy => true,
+            State::DefaultValue | State::Empty | State::Blank => self.is_empty(),
+        }
+    }
+
+    fn to_kstr(&self) -> liquid::model::KStringCow<'_> {
+        let s = ObjectRender::new(self).to_string();
+        KStringCow::from_string(s)
+    }
+
+    fn to_value(&self) -> LiquidValue {
+        LiquidValue::Object(self.iter().collect())
+    }
+
+    fn as_object(&self) -> Option<&dyn ObjectView> {
+        Some(self)
+    }
+}

milli/src/prompt/error.rs

@@ -0,0 +1,56 @@
+use crate::error::FaultSource;
+
+#[derive(Debug, thiserror::Error)]
+#[error("{fault}: {kind}")]
+pub struct NewPromptError {
+    pub kind: NewPromptErrorKind,
+    pub fault: FaultSource,
+}
+
+impl From<NewPromptError> for crate::Error {
+    fn from(value: NewPromptError) -> Self {
+        crate::Error::UserError(crate::UserError::InvalidPrompt(value))
+    }
+}
+
+impl NewPromptError {
+    pub(crate) fn cannot_parse_template(inner: liquid::Error) -> NewPromptError {
+        Self { kind: NewPromptErrorKind::CannotParseTemplate(inner), fault: FaultSource::User }
+    }
+
+    pub(crate) fn invalid_fields_in_template(inner: liquid::Error) -> NewPromptError {
+        Self { kind: NewPromptErrorKind::InvalidFieldsInTemplate(inner), fault: FaultSource::User }
+    }
+}
+
+#[derive(Debug, thiserror::Error)]
+pub enum NewPromptErrorKind {
+    #[error("cannot parse template: {0}")]
+    CannotParseTemplate(liquid::Error),
+    #[error("template contains invalid fields: {0}. Only `doc.*`, `fields[i].name`, `fields[i].value` are supported")]
+    InvalidFieldsInTemplate(liquid::Error),
+}
+
+#[derive(Debug, thiserror::Error)]
+#[error("{fault}: {kind}")]
+pub struct RenderPromptError {
+    pub kind: RenderPromptErrorKind,
+    pub fault: FaultSource,
+}
+impl RenderPromptError {
+    pub(crate) fn missing_context(inner: liquid::Error) -> RenderPromptError {
+        Self { kind: RenderPromptErrorKind::MissingContext(inner), fault: FaultSource::User }
+    }
+}
+
+#[derive(Debug, thiserror::Error)]
+pub enum RenderPromptErrorKind {
+    #[error("missing field in document: {0}")]
+    MissingContext(liquid::Error),
+}
+
+impl From<RenderPromptError> for crate::Error {
+    fn from(value: RenderPromptError) -> Self {
+        crate::Error::UserError(crate::UserError::MissingDocumentField(value))
+    }
+}

milli/src/prompt/fields.rs

@@ -0,0 +1,172 @@
+use liquid::model::{
+    ArrayView, DisplayCow, KStringCow, ObjectRender, ObjectSource, State, Value as LiquidValue,
+};
+use liquid::{ObjectView, ValueView};
+
+use super::document::Document;
+use crate::FieldsIdsMap;
+#[derive(Debug, Clone)]
+pub struct Fields<'a>(Vec<FieldValue<'a>>);
+
+impl<'a> Fields<'a> {
+    pub fn new(document: &'a Document<'a>, field_id_map: &'a FieldsIdsMap) -> Self {
+        Self(
+            std::iter::repeat(document)
+                .zip(field_id_map.iter())
+                .map(|(document, (_fid, name))| FieldValue { document, name })
+                .collect(),
+        )
+    }
+}
+
+#[derive(Debug, Clone, Copy)]
+pub struct FieldValue<'a> {
+    name: &'a str,
+    document: &'a Document<'a>,
+}
+
+impl<'a> ValueView for FieldValue<'a> {
+    fn as_debug(&self) -> &dyn std::fmt::Debug {
+        self
+    }
+
+    fn render(&self) -> liquid::model::DisplayCow<'_> {
+        DisplayCow::Owned(Box::new(ObjectRender::new(self)))
+    }
+
+    fn source(&self) -> liquid::model::DisplayCow<'_> {
+        DisplayCow::Owned(Box::new(ObjectSource::new(self)))
+    }
+
+    fn type_name(&self) -> &'static str {
+        "object"
+    }
+
+    fn query_state(&self, state: liquid::model::State) -> bool {
+        match state {
+            State::Truthy => true,
+            State::DefaultValue | State::Empty | State::Blank => self.is_empty(),
+        }
+    }
+
+    fn to_kstr(&self) -> liquid::model::KStringCow<'_> {
+        let s = ObjectRender::new(self).to_string();
+        KStringCow::from_string(s)
+    }
+
+    fn to_value(&self) -> LiquidValue {
+        LiquidValue::Object(
+            self.iter().map(|(k, v)| (k.to_string().into(), v.to_value())).collect(),
+        )
+    }
+
+    fn as_object(&self) -> Option<&dyn ObjectView> {
+        Some(self)
+    }
+}
+
+impl<'a> FieldValue<'a> {
+    pub fn name(&self) -> &&'a str {
+        &self.name
+    }
+
+    pub fn value(&self) -> &dyn ValueView {
+        self.document.get(self.name).unwrap_or(&LiquidValue::Nil)
+    }
+
+    pub fn is_empty(&self) -> bool {
+        self.size() == 0
+    }
+}
+
+impl<'a> ObjectView for FieldValue<'a> {
+    fn as_value(&self) -> &dyn ValueView {
+        self
+    }
+
+    fn size(&self) -> i64 {
+        2
+    }
+
+    fn keys<'k>(&'k self) -> Box<dyn Iterator<Item = KStringCow<'k>> + 'k> {
+        Box::new(["name", "value"].iter().map(|&x| KStringCow::from_static(x)))
+    }
+
+    fn values<'k>(&'k self) -> Box<dyn Iterator<Item = &'k dyn ValueView> + 'k> {
+        Box::new(
+            std::iter::once(self.name() as &dyn ValueView).chain(std::iter::once(self.value())),
+        )
+    }
+
+    fn iter<'k>(&'k self) -> Box<dyn Iterator<Item = (KStringCow<'k>, &'k dyn ValueView)> + 'k> {
+        Box::new(self.keys().zip(self.values()))
+    }
+
+    fn contains_key(&self, index: &str) -> bool {
+        index == "name" || index == "value"
+    }
+
+    fn get<'s>(&'s self, index: &str) -> Option<&'s dyn ValueView> {
+        match index {
+            "name" => Some(self.name()),
+            "value" => Some(self.value()),
+            _ => None,
+        }
+    }
+}
+
+impl<'a> ArrayView for Fields<'a> {
+    fn as_value(&self) -> &dyn ValueView {
+        self.0.as_value()
+    }
+
+    fn size(&self) -> i64 {
+        self.0.len() as i64
+    }
+
+    fn values<'k>(&'k self) -> Box<dyn Iterator<Item = &'k dyn ValueView> + 'k> {
+        self.0.values()
+    }
+
+    fn contains_key(&self, index: i64) -> bool {
+        self.0.contains_key(index)
+    }
+
+    fn get(&self, index: i64) -> Option<&dyn ValueView> {
+        ArrayView::get(&self.0, index)
+    }
+}
+
+impl<'a> ValueView for Fields<'a> {
+    fn as_debug(&self) -> &dyn std::fmt::Debug {
+        self
+    }
+
+    fn render(&self) -> liquid::model::DisplayCow<'_> {
+        self.0.render()
+    }
+
+    fn source(&self) -> liquid::model::DisplayCow<'_> {
+        self.0.source()
+    }
+
+    fn type_name(&self) -> &'static str {
+        self.0.type_name()
+    }
+
+    fn query_state(&self, state: liquid::model::State) -> bool {
+        self.0.query_state(state)
+    }
+
+    fn to_kstr(&self) -> liquid::model::KStringCow<'_> {
+        self.0.to_kstr()
+    }
+
+    fn to_value(&self) -> LiquidValue {
+        self.0.to_value()
+    }
+
+    fn as_array(&self) -> Option<&dyn ArrayView> {
+        Some(self)
+    }
+}

milli/src/prompt/mod.rs

@@ -0,0 +1,176 @@
+mod context;
+mod document;
+pub(crate) mod error;
+mod fields;
+mod template_checker;
+
+use std::convert::TryFrom;
+
+use error::{NewPromptError, RenderPromptError};
+
+use self::context::Context;
+use self::document::Document;
+use crate::update::del_add::DelAdd;
+use crate::FieldsIdsMap;
+
+pub struct Prompt {
+    template: liquid::Template,
+    template_text: String,
+}
+
+#[derive(Debug, Clone, serde::Serialize, serde::Deserialize)]
+pub struct PromptData {
+    pub template: String,
+}
+
+impl From<Prompt> for PromptData {
+    fn from(value: Prompt) -> Self {
+        Self { template: value.template_text }
+    }
+}
+
+impl TryFrom<PromptData> for Prompt {
+    type Error = NewPromptError;
+
+    fn try_from(value: PromptData) -> Result<Self, Self::Error> {
+        Prompt::new(value.template)
+    }
+}
+
+impl Clone for Prompt {
+    fn clone(&self) -> Self {
+        let template_text = self.template_text.clone();
+        Self { template: new_template(&template_text).unwrap(), template_text }
+    }
+}
+
+fn new_template(text: &str) -> Result<liquid::Template, liquid::Error> {
+    liquid::ParserBuilder::with_stdlib().build().unwrap().parse(text)
+}
+
+fn default_template() -> liquid::Template {
+    new_template(default_template_text()).unwrap()
+}
+
+fn default_template_text() -> &'static str {
+    "{% for field in fields %} \
+    {{ field.name }}: {{ field.value }}\n\
+    {% endfor %}"
+}
+
+impl Default for Prompt {
+    fn default() -> Self {
+        Self { template: default_template(), template_text: default_template_text().into() }
+    }
+}
+
+impl Default for PromptData {
+    fn default() -> Self {
+        Self { template: default_template_text().into() }
+    }
+}
+
+impl Prompt {
+    pub fn new(template: String) -> Result<Self, NewPromptError> {
+        let this = Self {
+            template: liquid::ParserBuilder::with_stdlib()
+                .build()
+                .unwrap()
+                .parse(&template)
+                .map_err(NewPromptError::cannot_parse_template)?,
+            template_text: template,
+        };
+
+        // render template with special object that's OK with `doc.*` and `fields.*`
+        this.template
+            .render(&template_checker::TemplateChecker)
+            .map_err(NewPromptError::invalid_fields_in_template)?;
+
+        Ok(this)
+    }
+
+    pub fn render(
+        &self,
+        document: obkv::KvReaderU16<'_>,
+        side: DelAdd,
+        field_id_map: &FieldsIdsMap,
+    ) -> Result<String, RenderPromptError> {
+        let document = Document::new(document, side, field_id_map);
+        let context = Context::new(&document, field_id_map);
+
+        self.template.render(&context).map_err(RenderPromptError::missing_context)
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::Prompt;
+    use crate::error::FaultSource;
+    use crate::prompt::error::{NewPromptError, NewPromptErrorKind};
+
+    #[test]
+    fn default_template() {
+        // does not panic
+        Prompt::default();
+    }
+
+    #[test]
+    fn empty_template() {
+        Prompt::new("".into()).unwrap();
+    }
+
+    #[test]
+    fn template_ok() {
+        Prompt::new("{{doc.title}}: {{doc.overview}}".into()).unwrap();
+    }
+
+    #[test]
+    fn template_syntax() {
+        assert!(matches!(
+            Prompt::new("{{doc.title: {{doc.overview}}".into()),
+            Err(NewPromptError {
+                kind: NewPromptErrorKind::CannotParseTemplate(_),
+                fault: FaultSource::User
+            })
+        ));
+    }
+
+    #[test]
+    fn template_missing_doc() {
+        assert!(matches!(
+            Prompt::new("{{title}}: {{overview}}".into()),
+            Err(NewPromptError {
+                kind: NewPromptErrorKind::InvalidFieldsInTemplate(_),
+                fault: FaultSource::User
+            })
+        ));
+    }
+
+    #[test]
+    fn template_nested_doc() {
+        Prompt::new("{{doc.actor.firstName}}: {{doc.actor.lastName}}".into()).unwrap();
+    }
+
+    #[test]
+    fn template_fields() {
+        Prompt::new("{% for field in fields %}{{field}}{% endfor %}".into()).unwrap();
+    }
+
+    #[test]
+    fn template_fields_ok() {
+        Prompt::new("{% for field in fields %}{{field.name}}: {{field.value}}{% endfor %}".into())
+            .unwrap();
+    }
+
+    #[test]
+    fn template_fields_invalid() {
+        assert!(matches!(
+            // intentionally garbled field
+            Prompt::new("{% for field in fields %}{{field.vaelu}} {% endfor %}".into()),
+            Err(NewPromptError {
+                kind: NewPromptErrorKind::InvalidFieldsInTemplate(_),
+                fault: FaultSource::User
+            })
+        ));
+    }
+}

milli/src/prompt/template_checker.rs

@@ -0,0 +1,301 @@
+use liquid::model::{
+    ArrayView, DisplayCow, KStringCow, ObjectRender, ObjectSource, State, Value as LiquidValue,
+};
+use liquid::{Object, ObjectView, ValueView};
+
+#[derive(Debug)]
+pub struct TemplateChecker;
+
+#[derive(Debug)]
+pub struct DummyDoc;
+
+#[derive(Debug)]
+pub struct DummyFields;
+
+#[derive(Debug)]
+pub struct DummyField;
+
+const DUMMY_VALUE: &LiquidValue = &LiquidValue::Nil;
+
+impl ObjectView for DummyField {
+    fn as_value(&self) -> &dyn ValueView {
+        self
+    }
+
+    fn size(&self) -> i64 {
+        2
+    }
+
+    fn keys<'k>(&'k self) -> Box<dyn Iterator<Item = KStringCow<'k>> + 'k> {
+        Box::new(["name", "value"].iter().map(|s| KStringCow::from_static(s)))
+    }
+
+    fn values<'k>(&'k self) -> Box<dyn Iterator<Item = &'k dyn ValueView> + 'k> {
+        Box::new(vec![DUMMY_VALUE.as_view(), DUMMY_VALUE.as_view()].into_iter())
+    }
+
+    fn iter<'k>(&'k self) -> Box<dyn Iterator<Item = (KStringCow<'k>, &'k dyn ValueView)> + 'k> {
+        Box::new(self.keys().zip(self.values()))
+    }
+
+    fn contains_key(&self, index: &str) -> bool {
+        index == "name" || index == "value"
+    }
+
+    fn get<'s>(&'s self, index: &str) -> Option<&'s dyn ValueView> {
+        if self.contains_key(index) {
+            Some(DUMMY_VALUE.as_view())
+        } else {
+            None
+        }
+    }
+}
+
+impl ValueView for DummyField {
+    fn as_debug(&self) -> &dyn std::fmt::Debug {
+        self
+    }
+
+    fn render(&self) -> DisplayCow<'_> {
+        DUMMY_VALUE.render()
+    }
+
+    fn source(&self) -> DisplayCow<'_> {
+        DUMMY_VALUE.source()
+    }
+
+    fn type_name(&self) -> &'static str {
+        "object"
+    }
+
+    fn query_state(&self, state: State) -> bool {
+        match state {
+            State::Truthy => true,
+            State::DefaultValue => false,
+            State::Empty => false,
+            State::Blank => false,
+        }
+    }
+
+    fn to_kstr(&self) -> KStringCow<'_> {
+        DUMMY_VALUE.to_kstr()
+    }
+
+    fn to_value(&self) -> LiquidValue {
+        let mut this = Object::new();
+        this.insert("name".into(), LiquidValue::Nil);
+        this.insert("value".into(), LiquidValue::Nil);
+        LiquidValue::Object(this)
+    }
+
+    fn as_object(&self) -> Option<&dyn ObjectView> {
+        Some(self)
+    }
+}
+
+impl ValueView for DummyFields {
+    fn as_debug(&self) -> &dyn std::fmt::Debug {
+        self
+    }
+
+    fn render(&self) -> DisplayCow<'_> {
+        DUMMY_VALUE.render()
+    }
+
+    fn source(&self) -> DisplayCow<'_> {
+        DUMMY_VALUE.source()
+    }
+
+    fn type_name(&self) -> &'static str {
+        "array"
+    }
+
+    fn query_state(&self, state: State) -> bool {
+        match state {
+            State::Truthy => true,
+            State::DefaultValue => false,
+            State::Empty => false,
+            State::Blank => false,
+        }
+    }
+
+    fn to_kstr(&self) -> KStringCow<'_> {
+        DUMMY_VALUE.to_kstr()
+    }
+
+    fn to_value(&self) -> LiquidValue {
+        LiquidValue::Array(vec![DummyField.to_value()])
+    }
+
+    fn as_array(&self) -> Option<&dyn ArrayView> {
+        Some(self)
+    }
+}
+
+impl ArrayView for DummyFields {
+    fn as_value(&self) -> &dyn ValueView {
+        self
+    }
+
+    fn size(&self) -> i64 {
+        u16::MAX as i64
+    }
+
+    fn values<'k>(&'k self) -> Box<dyn Iterator<Item = &'k dyn ValueView> + 'k> {
+        Box::new(std::iter::once(DummyField.as_value()))
+    }
+
+    fn contains_key(&self, index: i64) -> bool {
+        index < self.size()
+    }
+
+    fn get(&self, _index: i64) -> Option<&dyn ValueView> {
+        Some(DummyField.as_value())
+    }
+}
+
+impl ObjectView for DummyDoc {
+    fn as_value(&self) -> &dyn ValueView {
+        self
+    }
+
+    fn size(&self) -> i64 {
+        1000
+    }
+
+    fn keys<'k>(&'k self) -> Box<dyn Iterator<Item = KStringCow<'k>> + 'k> {
+        Box::new(std::iter::empty())
+    }
+
+    fn values<'k>(&'k self) -> Box<dyn Iterator<Item = &'k dyn ValueView> + 'k> {
+        Box::new(std::iter::empty())
+    }
+
+    fn iter<'k>(&'k self) -> Box<dyn Iterator<Item = (KStringCow<'k>, &'k dyn ValueView)> + 'k> {
+        Box::new(std::iter::empty())
+    }
+
+    fn contains_key(&self, _index: &str) -> bool {
+        true
+    }
+
+    fn get<'s>(&'s self, _index: &str) -> Option<&'s dyn ValueView> {
+        // Recursively sends itself
+        Some(self)
+    }
+}
+
+impl ValueView for DummyDoc {
+    fn as_debug(&self) -> &dyn std::fmt::Debug {
+        self
+    }
+
+    fn render(&self) -> DisplayCow<'_> {
+        DUMMY_VALUE.render()
+    }
+
+    fn source(&self) -> DisplayCow<'_> {
+        DUMMY_VALUE.source()
+    }
+
+    fn type_name(&self) -> &'static str {
+        "object"
+    }
+
+    fn query_state(&self, state: State) -> bool {
+        match state {
+            State::Truthy => true,
+            State::DefaultValue => false,
+            State::Empty => false,
+            State::Blank => false,
+        }
+    }
+
+    fn to_kstr(&self) -> KStringCow<'_> {
+        DUMMY_VALUE.to_kstr()
+    }
+
+    fn to_value(&self) -> LiquidValue {
+        LiquidValue::Nil
+    }
+
+    fn as_object(&self) -> Option<&dyn ObjectView> {
+        Some(self)
+    }
+}
+
+impl ObjectView for TemplateChecker {
+    fn as_value(&self) -> &dyn ValueView {
+        self
+    }
+
+    fn size(&self) -> i64 {
+        2
+    }
+
+    fn keys<'k>(&'k self) -> Box<dyn Iterator<Item = KStringCow<'k>> + 'k> {
+        Box::new(["doc", "fields"].iter().map(|s| KStringCow::from_static(s)))
+    }
+
+    fn values<'k>(&'k self) -> Box<dyn Iterator<Item = &'k dyn ValueView> + 'k> {
+        Box::new(
+            std::iter::once(DummyDoc.as_value()).chain(std::iter::once(DummyFields.as_value())),
+        )
+    }
+
+    fn iter<'k>(&'k self) -> Box<dyn Iterator<Item = (KStringCow<'k>, &'k dyn ValueView)> + 'k> {
+        Box::new(self.keys().zip(self.values()))
+    }
+
+    fn contains_key(&self, index: &str) -> bool {
+        index == "doc" || index == "fields"
+    }
+
+    fn get<'s>(&'s self, index: &str) -> Option<&'s dyn ValueView> {
+        match index {
+            "doc" => Some(DummyDoc.as_value()),
+            "fields" => Some(DummyFields.as_value()),
+            _ => None,
+        }
+    }
+}
+
+impl ValueView for TemplateChecker {
+    fn as_debug(&self) -> &dyn std::fmt::Debug {
+        self
+    }
+
+    fn render(&self) -> liquid::model::DisplayCow<'_> {
+        DisplayCow::Owned(Box::new(ObjectRender::new(self)))
+    }
+
+    fn source(&self) -> liquid::model::DisplayCow<'_> {
+        DisplayCow::Owned(Box::new(ObjectSource::new(self)))
+    }
+
+    fn type_name(&self) -> &'static str {
+        "object"
+    }
+
+    fn query_state(&self, state: liquid::model::State) -> bool {
+        match state {
+            State::Truthy => true,
+            State::DefaultValue | State::Empty | State::Blank => false,
+        }
+    }
+
+    fn to_kstr(&self) -> liquid::model::KStringCow<'_> {
+        let s = ObjectRender::new(self).to_string();
+        KStringCow::from_string(s)
+    }
+
+    fn to_value(&self) -> LiquidValue {
+        LiquidValue::Object(
+            self.iter().map(|(k, x)| (k.to_string().into(), x.to_value())).collect(),
+        )
+    }
+
+    fn as_object(&self) -> Option<&dyn ObjectView> {
+        Some(self)
+    }
+}

milli/src/readable_slices.rs

@@ -1,85 +0,0 @@
-use std::io::{self, Read};
-use std::iter::FromIterator;
-
-pub struct ReadableSlices<A> {
-    inner: Vec<A>,
-    pos: u64,
-}
-
-impl<A> FromIterator<A> for ReadableSlices<A> {
-    fn from_iter<T: IntoIterator<Item = A>>(iter: T) -> Self {
-        ReadableSlices { inner: iter.into_iter().collect(), pos: 0 }
-    }
-}
-
-impl<A: AsRef<[u8]>> Read for ReadableSlices<A> {
-    fn read(&mut self, mut buf: &mut [u8]) -> io::Result<usize> {
-        let original_buf_len = buf.len();
-
-        // We explore the list of slices to find the one where we must start reading.
-        let mut pos = self.pos;
-        let index = match self
-            .inner
-            .iter()
-            .map(|s| s.as_ref().len() as u64)
-            .position(|size| pos.checked_sub(size).map(|p| pos = p).is_none())
-        {
-            Some(index) => index,
-            None => return Ok(0),
-        };
-
-        let mut inner_pos = pos as usize;
-        for slice in &self.inner[index..] {
-            let slice = &slice.as_ref()[inner_pos..];
-
-            if buf.len() > slice.len() {
-                // We must exhaust the current slice and go to the next one there is not enough here.
-                buf[..slice.len()].copy_from_slice(slice);
-                buf = &mut buf[slice.len()..];
-                inner_pos = 0;
-            } else {
-                // There is enough in this slice to fill the remaining bytes of the buffer.
-                // Let's break just after filling it.
-                buf.copy_from_slice(&slice[..buf.len()]);
-                buf = &mut [];
-                break;
-            }
-        }
-
-        let written = original_buf_len - buf.len();
-        self.pos += written as u64;
-        Ok(written)
-    }
-}
-
-#[cfg(test)]
-mod test {
-    use std::io::Read;
-
-    use super::ReadableSlices;
-
-    #[test]
-    fn basic() {
-        let data: Vec<_> = (0..100).collect();
-        let splits: Vec<_> = data.chunks(3).collect();
-        let mut rdslices: ReadableSlices<_> = splits.into_iter().collect();
-
-        let mut output = Vec::new();
-        let length = rdslices.read_to_end(&mut output).unwrap();
-        assert_eq!(length, data.len());
-        assert_eq!(output, data);
-    }
-
-    #[test]
-    fn small_reads() {
-        let data: Vec<_> = (0..u8::MAX).collect();
-        let splits: Vec<_> = data.chunks(27).collect();
-        let mut rdslices: ReadableSlices<_> = splits.into_iter().collect();
-
-        let buffer = &mut [0; 45];
-        let length = rdslices.read(buffer).unwrap();
-        let expected: Vec<_> = (0..buffer.len() as u8).collect();
-        assert_eq!(length, buffer.len());
-        assert_eq!(buffer, &expected[..]);
-    }
-}

milli/src/score_details.rs

@@ -1,3 +1,6 @@
+use std::cmp::Ordering;
+
+use itertools::Itertools;
 use serde::Serialize;
 
 use crate::distance_between_two_points;
@@ -12,9 +15,24 @@ pub enum ScoreDetails {
     ExactAttribute(ExactAttribute),
     ExactWords(ExactWords),
     Sort(Sort),
+    Vector(Vector),
     GeoSort(GeoSort),
 }
 
+#[derive(Clone, Copy)]
+pub enum ScoreValue<'a> {
+    Score(f64),
+    Sort(&'a Sort),
+    GeoSort(&'a GeoSort),
+}
+
+enum RankOrValue<'a> {
+    Rank(Rank),
+    Sort(&'a Sort),
+    GeoSort(&'a GeoSort),
+    Score(f64),
+}
+
 impl ScoreDetails {
     pub fn local_score(&self) -> Option<f64> {
         self.rank().map(Rank::local_score)
@@ -31,11 +49,55 @@ impl ScoreDetails {
             ScoreDetails::ExactWords(details) => Some(details.rank()),
             ScoreDetails::Sort(_) => None,
             ScoreDetails::GeoSort(_) => None,
+            ScoreDetails::Vector(_) => None,
         }
     }
 
-    pub fn global_score<'a>(details: impl Iterator<Item = &'a Self>) -> f64 {
+    pub fn global_score<'a>(details: impl Iterator<Item = &'a Self> + 'a) -> f64 {
-        Rank::global_score(details.filter_map(Self::rank))
+        Self::score_values(details)
+            .find_map(|x| {
+                let ScoreValue::Score(score) = x else {
+                    return None;
+                };
+                Some(score)
+            })
+            .unwrap_or(1.0f64)
+    }
+
+    pub fn score_values<'a>(
+        details: impl Iterator<Item = &'a Self> + 'a,
+    ) -> impl Iterator<Item = ScoreValue<'a>> + 'a {
+        details
+            .map(ScoreDetails::rank_or_value)
+            .coalesce(|left, right| match (left, right) {
+                (RankOrValue::Rank(left), RankOrValue::Rank(right)) => {
+                    Ok(RankOrValue::Rank(Rank::merge(left, right)))
+                }
+                (left, right) => Err((left, right)),
+            })
+            .map(|rank_or_value| match rank_or_value {
+                RankOrValue::Rank(r) => ScoreValue::Score(r.local_score()),
+                RankOrValue::Sort(s) => ScoreValue::Sort(s),
+                RankOrValue::GeoSort(g) => ScoreValue::GeoSort(g),
+                RankOrValue::Score(s) => ScoreValue::Score(s),
+            })
+    }
+
+    fn rank_or_value(&self) -> RankOrValue<'_> {
+        match self {
+            ScoreDetails::Words(w) => RankOrValue::Rank(w.rank()),
+            ScoreDetails::Typo(t) => RankOrValue::Rank(t.rank()),
+            ScoreDetails::Proximity(p) => RankOrValue::Rank(*p),
+            ScoreDetails::Fid(f) => RankOrValue::Rank(*f),
+            ScoreDetails::Position(p) => RankOrValue::Rank(*p),
+            ScoreDetails::ExactAttribute(e) => RankOrValue::Rank(e.rank()),
+            ScoreDetails::ExactWords(e) => RankOrValue::Rank(e.rank()),
+            ScoreDetails::Sort(sort) => RankOrValue::Sort(sort),
+            ScoreDetails::GeoSort(geosort) => RankOrValue::GeoSort(geosort),
+            ScoreDetails::Vector(vector) => RankOrValue::Score(
+                vector.value_similarity.as_ref().map(|(_, s)| *s as f64).unwrap_or(0.0f64),
+            ),
+        }
     }
 
     /// Panics
@@ -181,6 +243,19 @@ impl ScoreDetails {
                     details_map.insert(sort, sort_details);
                     order += 1;
                 }
+                ScoreDetails::Vector(s) => {
+                    let vector = format!("vectorSort({:?})", s.target_vector);
+                    let value = s.value_similarity.as_ref().map(|(v, _)| v);
+                    let similarity = s.value_similarity.as_ref().map(|(_, s)| s);
+
+                    let details = serde_json::json!({
+                        "order": order,
+                        "value": value,
+                        "similarity": similarity,
+                    });
+                    details_map.insert(vector, details);
+                    order += 1;
+                }
             }
         }
         details_map
@@ -297,15 +372,21 @@ impl Rank {
     pub fn global_score(details: impl Iterator<Item = Self>) -> f64 {
         let mut rank = Rank { rank: 1, max_rank: 1 };
         for inner_rank in details {
-            rank.rank -= 1;
+            rank = Rank::merge(rank, inner_rank);
-
-            rank.rank *= inner_rank.max_rank;
-            rank.max_rank *= inner_rank.max_rank;
-
-            rank.rank += inner_rank.rank;
         }
         rank.local_score()
     }
+
+    pub fn merge(mut outer: Rank, inner: Rank) -> Rank {
+        outer.rank = outer.rank.saturating_sub(1);
+
+        outer.rank *= inner.max_rank;
+        outer.max_rank *= inner.max_rank;
+
+        outer.rank += inner.rank;
+
+        outer
+    }
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Serialize)]
@@ -335,13 +416,78 @@ pub struct Sort {
     pub value: serde_json::Value,
 }
 
-#[derive(Debug, Clone, Copy, PartialEq, PartialOrd)]
+impl PartialOrd for Sort {
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        if self.field_name != other.field_name {
+            return None;
+        }
+        if self.ascending != other.ascending {
+            return None;
+        }
+        match (&self.value, &other.value) {
+            (serde_json::Value::Null, serde_json::Value::Null) => Some(Ordering::Equal),
+            (serde_json::Value::Null, _) => Some(Ordering::Less),
+            (_, serde_json::Value::Null) => Some(Ordering::Greater),
+            // numbers are always before strings
+            (serde_json::Value::Number(_), serde_json::Value::String(_)) => Some(Ordering::Greater),
+            (serde_json::Value::String(_), serde_json::Value::Number(_)) => Some(Ordering::Less),
+            (serde_json::Value::Number(left), serde_json::Value::Number(right)) => {
+                // FIXME: unwrap permitted here?
+                let order = left.as_f64().unwrap().partial_cmp(&right.as_f64().unwrap())?;
+                // 12 < 42, and when ascending, we want to see 12 first, so the smallest.
+                // Hence, when ascending, smaller is better
+                Some(if self.ascending { order.reverse() } else { order })
+            }
+            (serde_json::Value::String(left), serde_json::Value::String(right)) => {
+                let order = left.cmp(right);
+                // Taking e.g. "a" and "z"
+                // "a" < "z", and when ascending, we want to see "a" first, so the smallest.
+                // Hence, when ascending, smaller is better
+                Some(if self.ascending { order.reverse() } else { order })
+            }
+            _ => None,
+        }
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq)]
 pub struct GeoSort {
     pub target_point: [f64; 2],
     pub ascending: bool,
     pub value: Option<[f64; 2]>,
 }
 
+impl PartialOrd for GeoSort {
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        if self.target_point != other.target_point {
+            return None;
+        }
+        if self.ascending != other.ascending {
+            return None;
+        }
+        Some(match (self.distance(), other.distance()) {
+            (None, None) => Ordering::Equal,
+            (None, Some(_)) => Ordering::Less,
+            (Some(_), None) => Ordering::Greater,
+            (Some(left), Some(right)) => {
+                let order = left.partial_cmp(&right)?;
+                if self.ascending {
+                    // when ascending, the one with the smallest distance has the best score
+                    order.reverse()
+                } else {
+                    order
+                }
+            }
+        })
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, PartialOrd)]
+pub struct Vector {
+    pub target_vector: Vec<f32>,
+    pub value_similarity: Option<(Vec<f32>, f32)>,
+}
+
 impl GeoSort {
     pub fn distance(&self) -> Option<f64> {
         self.value.map(|value| distance_between_two_points(&self.target_point, &value))

milli/src/search/hybrid.rs

@@ -0,0 +1,183 @@
+use std::cmp::Ordering;
+
+use itertools::Itertools;
+use roaring::RoaringBitmap;
+
+use crate::score_details::{ScoreDetails, ScoreValue, ScoringStrategy};
+use crate::{MatchingWords, Result, Search, SearchResult};
+
+struct ScoreWithRatioResult {
+    matching_words: MatchingWords,
+    candidates: RoaringBitmap,
+    document_scores: Vec<(u32, ScoreWithRatio)>,
+}
+
+type ScoreWithRatio = (Vec<ScoreDetails>, f32);
+
+fn compare_scores(
+    &(ref left_scores, left_ratio): &ScoreWithRatio,
+    &(ref right_scores, right_ratio): &ScoreWithRatio,
+) -> Ordering {
+    let mut left_it = ScoreDetails::score_values(left_scores.iter());
+    let mut right_it = ScoreDetails::score_values(right_scores.iter());
+
+    loop {
+        let left = left_it.next();
+        let right = right_it.next();
+
+        match (left, right) {
+            (None, None) => return Ordering::Equal,
+            (None, Some(_)) => return Ordering::Less,
+            (Some(_), None) => return Ordering::Greater,
+            (Some(ScoreValue::Score(left)), Some(ScoreValue::Score(right))) => {
+                let left = left * left_ratio as f64;
+                let right = right * right_ratio as f64;
+                if (left - right).abs() <= f64::EPSILON {
+                    continue;
+                }
+                return left.partial_cmp(&right).unwrap();
+            }
+            (Some(ScoreValue::Sort(left)), Some(ScoreValue::Sort(right))) => {
+                match left.partial_cmp(right).unwrap() {
+                    Ordering::Equal => continue,
+                    order => return order,
+                }
+            }
+            (Some(ScoreValue::GeoSort(left)), Some(ScoreValue::GeoSort(right))) => {
+                match left.partial_cmp(right).unwrap() {
+                    Ordering::Equal => continue,
+                    order => return order,
+                }
+            }
+            (Some(ScoreValue::Score(_)), Some(_)) => return Ordering::Greater,
+            (Some(_), Some(ScoreValue::Score(_))) => return Ordering::Less,
+            // if we have this, we're bad
+            (Some(ScoreValue::GeoSort(_)), Some(ScoreValue::Sort(_)))
+            | (Some(ScoreValue::Sort(_)), Some(ScoreValue::GeoSort(_))) => {
+                unreachable!("Unexpected geo and sort comparison")
+            }
+        }
+    }
+}
+
+impl ScoreWithRatioResult {
+    fn new(results: SearchResult, ratio: f32) -> Self {
+        let document_scores = results
+            .documents_ids
+            .into_iter()
+            .zip(results.document_scores.into_iter().map(|scores| (scores, ratio)))
+            .collect();
+
+        Self {
+            matching_words: results.matching_words,
+            candidates: results.candidates,
+            document_scores,
+        }
+    }
+
+    fn merge(left: Self, right: Self, from: usize, length: usize) -> SearchResult {
+        let mut documents_ids =
+            Vec::with_capacity(left.document_scores.len() + right.document_scores.len());
+        let mut document_scores =
+            Vec::with_capacity(left.document_scores.len() + right.document_scores.len());
+
+        let mut documents_seen = RoaringBitmap::new();
+        for (docid, (main_score, _sub_score)) in left
+            .document_scores
+            .into_iter()
+            .merge_by(right.document_scores.into_iter(), |(_, left), (_, right)| {
+                // the first value is the one with the greatest score
+                compare_scores(left, right).is_ge()
+            })
+            // remove documents we already saw
+            .filter(|(docid, _)| documents_seen.insert(*docid))
+            // start skipping **after** the filter
+            .skip(from)
+            // take **after** skipping
+            .take(length)
+        {
+            documents_ids.push(docid);
+            // TODO: pass both scores to documents_score in some way?
+            document_scores.push(main_score);
+        }
+
+        SearchResult {
+            matching_words: left.matching_words,
+            candidates: left.candidates | right.candidates,
+            documents_ids,
+            document_scores,
+        }
+    }
+}
+
+impl<'a> Search<'a> {
+    pub fn execute_hybrid(&self, semantic_ratio: f32) -> Result<SearchResult> {
+        // TODO: find classier way to achieve that than to reset vector and query params
+        // create separate keyword and semantic searches
+        let mut search = Search {
+            query: self.query.clone(),
+            vector: self.vector.clone(),
+            filter: self.filter.clone(),
+            offset: 0,
+            limit: self.limit + self.offset,
+            sort_criteria: self.sort_criteria.clone(),
+            searchable_attributes: self.searchable_attributes,
+            geo_strategy: self.geo_strategy,
+            terms_matching_strategy: self.terms_matching_strategy,
+            scoring_strategy: ScoringStrategy::Detailed,
+            words_limit: self.words_limit,
+            exhaustive_number_hits: self.exhaustive_number_hits,
+            rtxn: self.rtxn,
+            index: self.index,
+            distribution_shift: self.distribution_shift,
+            embedder_name: self.embedder_name.clone(),
+        };
+
+        let vector_query = search.vector.take();
+        let keyword_results = search.execute()?;
+
+        // skip semantic search if we don't have a vector query (placeholder search)
+        let Some(vector_query) = vector_query else {
+            return Ok(keyword_results);
+        };
+
+        // completely skip semantic search if the results of the keyword search are good enough
+        if self.results_good_enough(&keyword_results, semantic_ratio) {
+            return Ok(keyword_results);
+        }
+
+        search.vector = Some(vector_query);
+        search.query = None;
+
+        // TODO: would be better to have two distinct functions at this point
+        let vector_results = search.execute()?;
+
+        let keyword_results = ScoreWithRatioResult::new(keyword_results, 1.0 - semantic_ratio);
+        let vector_results = ScoreWithRatioResult::new(vector_results, semantic_ratio);
+
+        let merge_results =
+            ScoreWithRatioResult::merge(vector_results, keyword_results, self.offset, self.limit);
+        assert!(merge_results.documents_ids.len() <= self.limit);
+        Ok(merge_results)
+    }
+
+    fn results_good_enough(&self, keyword_results: &SearchResult, semantic_ratio: f32) -> bool {
+        // A result is good enough if its keyword score is > 0.9 with a semantic ratio of 0.5 => 0.9 * 0.5
+        const GOOD_ENOUGH_SCORE: f64 = 0.45;
+
+        // 1. we check that we got a sufficient number of results
+        if keyword_results.document_scores.len() < self.limit + self.offset {
+            return false;
+        }
+
+        // 2. and that all results have a good enough score.
+        // we need to check all results because due to sort like rules, they're not necessarily in relevancy order
+        for score in &keyword_results.document_scores {
+            let score = ScoreDetails::global_score(score.iter());
+            if score * ((1.0 - semantic_ratio) as f64) < GOOD_ENOUGH_SCORE {
+                return false;
+            }
+        }
+        true
+    }
+}

milli/src/search/mod.rs

@@ -12,12 +12,14 @@ use roaring::bitmap::RoaringBitmap;
 
 pub use self::facet::{FacetDistribution, Filter, OrderBy, DEFAULT_VALUES_PER_FACET};
 pub use self::new::matches::{FormatOptions, MatchBounds, MatcherBuilder, MatchingWords};
-use self::new::PartialSearchResult;
+use self::new::{execute_vector_search, PartialSearchResult};
 use crate::error::UserError;
 use crate::heed_codec::facet::{FacetGroupKey, FacetGroupValue};
 use crate::score_details::{ScoreDetails, ScoringStrategy};
+use crate::vector::DistributionShift;
 use crate::{
-    execute_search, AscDesc, DefaultSearchLogger, DocumentId, FieldId, Index, Result, SearchContext,
+    execute_search, filtered_universe, AscDesc, DefaultSearchLogger, DocumentId, FieldId, Index,
+    Result, SearchContext,
 };
 
 // Building these factories is not free.
@@ -30,6 +32,7 @@ const MAX_NUMBER_OF_FACETS: usize = 100;
 
 pub mod facet;
 mod fst_utils;
+pub mod hybrid;
 pub mod new;
 
 pub struct Search<'a> {
@@ -46,8 +49,11 @@ pub struct Search<'a> {
     scoring_strategy: ScoringStrategy,
     words_limit: usize,
     exhaustive_number_hits: bool,
+    /// TODO: Add semantic ratio or pass it directly to execute_hybrid()
     rtxn: &'a heed::RoTxn<'a>,
     index: &'a Index,
+    distribution_shift: Option<DistributionShift>,
+    embedder_name: Option<String>,
 }
 
 impl<'a> Search<'a> {
@@ -67,6 +73,8 @@ impl<'a> Search<'a> {
             words_limit: 10,
             rtxn,
             index,
+            distribution_shift: None,
+            embedder_name: None,
         }
     }
 
@@ -75,8 +83,8 @@ impl<'a> Search<'a> {
         self
     }
 
-    pub fn vector(&mut self, vector: impl Into<Vec<f32>>) -> &mut Search<'a> {
+    pub fn vector(&mut self, vector: Vec<f32>) -> &mut Search<'a> {
-        self.vector = Some(vector.into());
+        self.vector = Some(vector);
         self
     }
 
@@ -133,30 +141,75 @@ impl<'a> Search<'a> {
         self
     }
 
+    pub fn distribution_shift(
+        &mut self,
+        distribution_shift: Option<DistributionShift>,
+    ) -> &mut Search<'a> {
+        self.distribution_shift = distribution_shift;
+        self
+    }
+
+    pub fn embedder_name(&mut self, embedder_name: impl Into<String>) -> &mut Search<'a> {
+        self.embedder_name = Some(embedder_name.into());
+        self
+    }
+
+    pub fn execute_for_candidates(&self, has_vector_search: bool) -> Result<RoaringBitmap> {
+        if has_vector_search {
+            let ctx = SearchContext::new(self.index, self.rtxn);
+            filtered_universe(&ctx, &self.filter)
+        } else {
+            Ok(self.execute()?.candidates)
+        }
+    }
+
     pub fn execute(&self) -> Result<SearchResult> {
+        let embedder_name;
+        let embedder_name = match &self.embedder_name {
+            Some(embedder_name) => embedder_name,
+            None => {
+                embedder_name = self.index.default_embedding_name(self.rtxn)?;
+                &embedder_name
+            }
+        };
+
         let mut ctx = SearchContext::new(self.index, self.rtxn);
 
         if let Some(searchable_attributes) = self.searchable_attributes {
             ctx.searchable_attributes(searchable_attributes)?;
         }
 
+        let universe = filtered_universe(&ctx, &self.filter)?;
         let PartialSearchResult { located_query_terms, candidates, documents_ids, document_scores } =
-            execute_search(
+            match self.vector.as_ref() {
-                &mut ctx,
+                Some(vector) => execute_vector_search(
-                &self.query,
+                    &mut ctx,
-                &self.vector,
+                    vector,
-                self.terms_matching_strategy,
+                    self.scoring_strategy,
-                self.scoring_strategy,
+                    universe,
-                self.exhaustive_number_hits,
+                    &self.sort_criteria,
-                &self.filter,
+                    self.geo_strategy,
-                &self.sort_criteria,
+                    self.offset,
-                self.geo_strategy,
+                    self.limit,
-                self.offset,
+                    self.distribution_shift,
-                self.limit,
+                    embedder_name,
-                Some(self.words_limit),
+                )?,
-                &mut DefaultSearchLogger,
+                None => execute_search(
-                &mut DefaultSearchLogger,
+                    &mut ctx,
-            )?;
+                    self.query.as_deref(),
+                    self.terms_matching_strategy,
+                    self.scoring_strategy,
+                    self.exhaustive_number_hits,
+                    universe,
+                    &self.sort_criteria,
+                    self.geo_strategy,
+                    self.offset,
+                    self.limit,
+                    Some(self.words_limit),
+                    &mut DefaultSearchLogger,
+                    &mut DefaultSearchLogger,
+                )?,
+            };
 
         // consume context and located_query_terms to build MatchingWords.
         let matching_words = match located_query_terms {
@@ -185,6 +238,8 @@ impl fmt::Debug for Search<'_> {
             exhaustive_number_hits,
             rtxn: _,
             index: _,
+            distribution_shift,
+            embedder_name,
         } = self;
         f.debug_struct("Search")
             .field("query", query)
@@ -198,6 +253,8 @@ impl fmt::Debug for Search<'_> {
             .field("scoring_strategy", scoring_strategy)
             .field("exhaustive_number_hits", exhaustive_number_hits)
             .field("words_limit", words_limit)
+            .field("distribution_shift", distribution_shift)
+            .field("embedder_name", embedder_name)
             .finish()
     }
 }
@@ -249,11 +306,16 @@ pub struct SearchForFacetValues<'a> {
     query: Option<String>,
     facet: String,
     search_query: Search<'a>,
+    is_hybrid: bool,
 }
 
 impl<'a> SearchForFacetValues<'a> {
-    pub fn new(facet: String, search_query: Search<'a>) -> SearchForFacetValues<'a> {
+    pub fn new(
-        SearchForFacetValues { query: None, facet, search_query }
+        facet: String,
+        search_query: Search<'a>,
+        is_hybrid: bool,
+    ) -> SearchForFacetValues<'a> {
+        SearchForFacetValues { query: None, facet, search_query, is_hybrid }
     }
 
     pub fn query(&mut self, query: impl Into<String>) -> &mut Self {
@@ -303,7 +365,9 @@ impl<'a> SearchForFacetValues<'a> {
             None => return Ok(vec![]),
         };
 
-        let search_candidates = self.search_query.execute()?.candidates;
+        let search_candidates = self
+            .search_query
+            .execute_for_candidates(self.is_hybrid || self.search_query.vector.is_some())?;
 
         match self.query.as_ref() {
             Some(query) => {

milli/src/search/new/geo_sort.rs

@@ -107,12 +107,16 @@ impl<Q: RankingRuleQueryTrait> GeoSort<Q> {
 
     /// Refill the internal buffer of cached docids based on the strategy.
     /// Drop the rtree if we don't need it anymore.
-    fn fill_buffer(&mut self, ctx: &mut SearchContext) -> Result<()> {
+    fn fill_buffer(
+        &mut self,
+        ctx: &mut SearchContext,
+        geo_candidates: &RoaringBitmap,
+    ) -> Result<()> {
         debug_assert!(self.field_ids.is_some(), "fill_buffer can't be called without the lat&lng");
         debug_assert!(self.cached_sorted_docids.is_empty());
 
         // lazily initialize the rtree if needed by the strategy, and cache it in `self.rtree`
-        let rtree = if self.strategy.use_rtree(self.geo_candidates.len() as usize) {
+        let rtree = if self.strategy.use_rtree(geo_candidates.len() as usize) {
             if let Some(rtree) = self.rtree.as_ref() {
                 // get rtree from cache
                 Some(rtree)
@@ -131,7 +135,7 @@ impl<Q: RankingRuleQueryTrait> GeoSort<Q> {
             if self.ascending {
                 let point = lat_lng_to_xyz(&self.point);
                 for point in rtree.nearest_neighbor_iter(&point) {
-                    if self.geo_candidates.contains(point.data.0) {
+                    if geo_candidates.contains(point.data.0) {
                         self.cached_sorted_docids.push_back(point.data);
                         if self.cached_sorted_docids.len() >= cache_size {
                             break;
@@ -143,7 +147,7 @@ impl<Q: RankingRuleQueryTrait> GeoSort<Q> {
                 // and we insert the points in reverse order they get reversed when emptying the cache later on
                 let point = lat_lng_to_xyz(&opposite_of(self.point));
                 for point in rtree.nearest_neighbor_iter(&point) {
-                    if self.geo_candidates.contains(point.data.0) {
+                    if geo_candidates.contains(point.data.0) {
                         self.cached_sorted_docids.push_front(point.data);
                         if self.cached_sorted_docids.len() >= cache_size {
                             break;
@@ -155,8 +159,7 @@ impl<Q: RankingRuleQueryTrait> GeoSort<Q> {
             // the iterative version
             let [lat, lng] = self.field_ids.unwrap();
 
-            let mut documents = self
+            let mut documents = geo_candidates
-                .geo_candidates
                 .iter()
                 .map(|id| -> Result<_> { Ok((id, geo_value(id, lat, lng, ctx.index, ctx.txn)?)) })
                 .collect::<Result<Vec<(u32, [f64; 2])>>>()?;
@@ -216,9 +219,10 @@ impl<'ctx, Q: RankingRuleQueryTrait> RankingRule<'ctx, Q> for GeoSort<Q> {
         assert!(self.query.is_none());
 
         self.query = Some(query.clone());
-        self.geo_candidates &= universe;
 
-        if self.geo_candidates.is_empty() {
+        let geo_candidates = &self.geo_candidates & universe;
+
+        if geo_candidates.is_empty() {
             return Ok(());
         }
 
@@ -226,7 +230,7 @@ impl<'ctx, Q: RankingRuleQueryTrait> RankingRule<'ctx, Q> for GeoSort<Q> {
         let lat = fid_map.id("_geo.lat").expect("geo candidates but no fid for lat");
         let lng = fid_map.id("_geo.lng").expect("geo candidates but no fid for lng");
         self.field_ids = Some([lat, lng]);
-        self.fill_buffer(ctx)?;
+        self.fill_buffer(ctx, &geo_candidates)?;
         Ok(())
     }
 
@@ -238,9 +242,10 @@ impl<'ctx, Q: RankingRuleQueryTrait> RankingRule<'ctx, Q> for GeoSort<Q> {
         universe: &RoaringBitmap,
     ) -> Result<Option<RankingRuleOutput<Q>>> {
         let query = self.query.as_ref().unwrap().clone();
-        self.geo_candidates &= universe;
 
-        if self.geo_candidates.is_empty() {
+        let geo_candidates = &self.geo_candidates & universe;
+
+        if geo_candidates.is_empty() {
             return Ok(Some(RankingRuleOutput {
                 query,
                 candidates: universe.clone(),
@@ -261,7 +266,7 @@ impl<'ctx, Q: RankingRuleQueryTrait> RankingRule<'ctx, Q> for GeoSort<Q> {
             }
         };
         while let Some((id, point)) = next(&mut self.cached_sorted_docids) {
-            if self.geo_candidates.contains(id) {
+            if geo_candidates.contains(id) {
                 return Ok(Some(RankingRuleOutput {
                     query,
                     candidates: RoaringBitmap::from_iter([id]),
@@ -276,7 +281,7 @@ impl<'ctx, Q: RankingRuleQueryTrait> RankingRule<'ctx, Q> for GeoSort<Q> {
 
         // if we got out of this loop it means we've exhausted our cache.
         // we need to refill it and run the function again.
-        self.fill_buffer(ctx)?;
+        self.fill_buffer(ctx, &geo_candidates)?;
         self.next_bucket(ctx, logger, universe)
     }
 

milli/src/search/new/matches/mod.rs

@@ -498,19 +498,19 @@ mod tests {
 
     use super::*;
     use crate::index::tests::TempIndex;
-    use crate::{execute_search, SearchContext};
+    use crate::{execute_search, filtered_universe, SearchContext};
 
     impl<'a> MatcherBuilder<'a> {
         fn new_test(rtxn: &'a heed::RoTxn, index: &'a TempIndex, query: &str) -> Self {
             let mut ctx = SearchContext::new(index, rtxn);
+            let universe = filtered_universe(&ctx, &None).unwrap();
             let crate::search::PartialSearchResult { located_query_terms, .. } = execute_search(
                 &mut ctx,
-                &Some(query.to_string()),
+                Some(query),
-                &None,
                 crate::TermsMatchingStrategy::default(),
                 crate::score_details::ScoringStrategy::Skip,
                 false,
-                &None,
+                universe,
                 &None,
                 crate::search::new::GeoSortStrategy::default(),
                 0,

milli/src/search/new/mod.rs

@@ -16,6 +16,7 @@ mod small_bitmap;
 
 mod exact_attribute;
 mod sort;
+mod vector_sort;
 
 #[cfg(test)]
 mod tests;
@@ -28,7 +29,6 @@ use db_cache::DatabaseCache;
 use exact_attribute::ExactAttribute;
 use graph_based_ranking_rule::{Exactness, Fid, Position, Proximity, Typo};
 use heed::RoTxn;
-use instant_distance::Search;
 use interner::{DedupInterner, Interner};
 pub use logger::visual::VisualSearchLogger;
 pub use logger::{DefaultSearchLogger, SearchLogger};
@@ -46,10 +46,11 @@ use self::geo_sort::GeoSort;
 pub use self::geo_sort::Strategy as GeoSortStrategy;
 use self::graph_based_ranking_rule::Words;
 use self::interner::Interned;
-use crate::distance::NDotProductPoint;
+use self::vector_sort::VectorSort;
 use crate::error::FieldIdMapMissingEntry;
 use crate::score_details::{ScoreDetails, ScoringStrategy};
 use crate::search::new::distinct::apply_distinct_rule;
+use crate::vector::DistributionShift;
 use crate::{
     AscDesc, DocumentId, FieldId, Filter, Index, Member, Result, TermsMatchingStrategy, UserError,
 };
@@ -258,6 +259,80 @@ fn get_ranking_rules_for_placeholder_search<'ctx>(
     Ok(ranking_rules)
 }
 
+fn get_ranking_rules_for_vector<'ctx>(
+    ctx: &SearchContext<'ctx>,
+    sort_criteria: &Option<Vec<AscDesc>>,
+    geo_strategy: geo_sort::Strategy,
+    limit_plus_offset: usize,
+    target: &[f32],
+    distribution_shift: Option<DistributionShift>,
+    embedder_name: &str,
+) -> Result<Vec<BoxRankingRule<'ctx, PlaceholderQuery>>> {
+    // query graph search
+
+    let mut sort = false;
+    let mut sorted_fields = HashSet::new();
+    let mut geo_sorted = false;
+
+    let mut vector = false;
+    let mut ranking_rules: Vec<BoxRankingRule<PlaceholderQuery>> = vec![];
+
+    let settings_ranking_rules = ctx.index.criteria(ctx.txn)?;
+    for rr in settings_ranking_rules {
+        match rr {
+            crate::Criterion::Words
+            | crate::Criterion::Typo
+            | crate::Criterion::Proximity
+            | crate::Criterion::Attribute
+            | crate::Criterion::Exactness => {
+                if !vector {
+                    let vector_candidates = ctx.index.documents_ids(ctx.txn)?;
+                    let vector_sort = VectorSort::new(
+                        ctx,
+                        target.to_vec(),
+                        vector_candidates,
+                        limit_plus_offset,
+                        distribution_shift,
+                        embedder_name,
+                    )?;
+                    ranking_rules.push(Box::new(vector_sort));
+                    vector = true;
+                }
+            }
+            crate::Criterion::Sort => {
+                if sort {
+                    continue;
+                }
+                resolve_sort_criteria(
+                    sort_criteria,
+                    ctx,
+                    &mut ranking_rules,
+                    &mut sorted_fields,
+                    &mut geo_sorted,
+                    geo_strategy,
+                )?;
+                sort = true;
+            }
+            crate::Criterion::Asc(field_name) => {
+                if sorted_fields.contains(&field_name) {
+                    continue;
+                }
+                sorted_fields.insert(field_name.clone());
+                ranking_rules.push(Box::new(Sort::new(ctx.index, ctx.txn, field_name, true)?));
+            }
+            crate::Criterion::Desc(field_name) => {
+                if sorted_fields.contains(&field_name) {
+                    continue;
+                }
+                sorted_fields.insert(field_name.clone());
+                ranking_rules.push(Box::new(Sort::new(ctx.index, ctx.txn, field_name, false)?));
+            }
+        }
+    }
+
+    Ok(ranking_rules)
+}
+
 /// Return the list of initialised ranking rules to be used for a query graph search.
 fn get_ranking_rules_for_query_graph_search<'ctx>(
     ctx: &SearchContext<'ctx>,
@@ -422,15 +497,72 @@ fn resolve_sort_criteria<'ctx, Query: RankingRuleQueryTrait>(
     Ok(())
 }
 
+pub fn filtered_universe(ctx: &SearchContext, filters: &Option<Filter>) -> Result<RoaringBitmap> {
+    Ok(if let Some(filters) = filters {
+        filters.evaluate(ctx.txn, ctx.index)?
+    } else {
+        ctx.index.documents_ids(ctx.txn)?
+    })
+}
+
+#[allow(clippy::too_many_arguments)]
+pub fn execute_vector_search(
+    ctx: &mut SearchContext,
+    vector: &[f32],
+    scoring_strategy: ScoringStrategy,
+    universe: RoaringBitmap,
+    sort_criteria: &Option<Vec<AscDesc>>,
+    geo_strategy: geo_sort::Strategy,
+    from: usize,
+    length: usize,
+    distribution_shift: Option<DistributionShift>,
+    embedder_name: &str,
+) -> Result<PartialSearchResult> {
+    check_sort_criteria(ctx, sort_criteria.as_ref())?;
+
+    // FIXME: input universe = universe & documents_with_vectors
+    // for now if we're computing embeddings for ALL documents, we can assume that this is just universe
+    let ranking_rules = get_ranking_rules_for_vector(
+        ctx,
+        sort_criteria,
+        geo_strategy,
+        from + length,
+        vector,
+        distribution_shift,
+        embedder_name,
+    )?;
+
+    let mut placeholder_search_logger = logger::DefaultSearchLogger;
+    let placeholder_search_logger: &mut dyn SearchLogger<PlaceholderQuery> =
+        &mut placeholder_search_logger;
+
+    let BucketSortOutput { docids, scores, all_candidates } = bucket_sort(
+        ctx,
+        ranking_rules,
+        &PlaceholderQuery,
+        &universe,
+        from,
+        length,
+        scoring_strategy,
+        placeholder_search_logger,
+    )?;
+
+    Ok(PartialSearchResult {
+        candidates: all_candidates,
+        document_scores: scores,
+        documents_ids: docids,
+        located_query_terms: None,
+    })
+}
+
 #[allow(clippy::too_many_arguments)]
 pub fn execute_search(
     ctx: &mut SearchContext,
-    query: &Option<String>,
+    query: Option<&str>,
-    vector: &Option<Vec<f32>>,
     terms_matching_strategy: TermsMatchingStrategy,
     scoring_strategy: ScoringStrategy,
     exhaustive_number_hits: bool,
-    filters: &Option<Filter>,
+    mut universe: RoaringBitmap,
     sort_criteria: &Option<Vec<AscDesc>>,
     geo_strategy: geo_sort::Strategy,
     from: usize,
@@ -439,60 +571,8 @@ pub fn execute_search(
     placeholder_search_logger: &mut dyn SearchLogger<PlaceholderQuery>,
     query_graph_logger: &mut dyn SearchLogger<QueryGraph>,
 ) -> Result<PartialSearchResult> {
-    let mut universe = if let Some(filters) = filters {
-        filters.evaluate(ctx.txn, ctx.index)?
-    } else {
-        ctx.index.documents_ids(ctx.txn)?
-    };
-
     check_sort_criteria(ctx, sort_criteria.as_ref())?;
 
-    if let Some(vector) = vector {
-        let mut search = Search::default();
-        let docids = match ctx.index.vector_hnsw(ctx.txn)? {
-            Some(hnsw) => {
-                if let Some(expected_size) = hnsw.iter().map(|(_, point)| point.len()).next() {
-                    if vector.len() != expected_size {
-                        return Err(UserError::InvalidVectorDimensions {
-                            expected: expected_size,
-                            found: vector.len(),
-                        }
-                        .into());
-                    }
-                }
-
-                let vector = NDotProductPoint::new(vector.clone());
-
-                let neighbors = hnsw.search(&vector, &mut search);
-
-                let mut docids = Vec::new();
-                let mut uniq_docids = RoaringBitmap::new();
-                for instant_distance::Item { distance: _, pid, point: _ } in neighbors {
-                    let index = pid.into_inner();
-                    let docid = ctx.index.vector_id_docid.get(ctx.txn, &index)?.unwrap();
-                    if universe.contains(docid) && uniq_docids.insert(docid) {
-                        docids.push(docid);
-                        if docids.len() == (from + length) {
-                            break;
-                        }
-                    }
-                }
-
-                // return the nearest documents that are also part of the candidates
-                // along with a dummy list of scores that are useless in this context.
-                docids.into_iter().skip(from).take(length).collect()
-            }
-            None => Vec::new(),
-        };
-
-        return Ok(PartialSearchResult {
-            candidates: universe,
-            document_scores: vec![Vec::new(); docids.len()],
-            documents_ids: docids,
-            located_query_terms: None,
-        });
-    }
-
     let mut located_query_terms = None;
     let query_terms = if let Some(query) = query {
         // We make sure that the analyzer is aware of the stop words
@@ -546,7 +626,7 @@ pub fn execute_search(
             terms_matching_strategy,
         )?;
 
-        universe =
+        universe &=
             resolve_universe(ctx, &universe, &graph, terms_matching_strategy, query_graph_logger)?;
 
         bucket_sort(

milli/src/search/new/vector_sort.rs

@@ -0,0 +1,170 @@
+use std::iter::FromIterator;
+
+use ordered_float::OrderedFloat;
+use roaring::RoaringBitmap;
+
+use super::ranking_rules::{RankingRule, RankingRuleOutput, RankingRuleQueryTrait};
+use crate::score_details::{self, ScoreDetails};
+use crate::vector::DistributionShift;
+use crate::{DocumentId, Result, SearchContext, SearchLogger};
+
+pub struct VectorSort<Q: RankingRuleQueryTrait> {
+    query: Option<Q>,
+    target: Vec<f32>,
+    vector_candidates: RoaringBitmap,
+    cached_sorted_docids: std::vec::IntoIter<(DocumentId, f32, Vec<f32>)>,
+    limit: usize,
+    distribution_shift: Option<DistributionShift>,
+    embedder_index: u8,
+}
+
+impl<Q: RankingRuleQueryTrait> VectorSort<Q> {
+    pub fn new(
+        ctx: &SearchContext,
+        target: Vec<f32>,
+        vector_candidates: RoaringBitmap,
+        limit: usize,
+        distribution_shift: Option<DistributionShift>,
+        embedder_name: &str,
+    ) -> Result<Self> {
+        let embedder_index = ctx
+            .index
+            .embedder_category_id
+            .get(ctx.txn, embedder_name)?
+            .ok_or_else(|| crate::UserError::InvalidEmbedder(embedder_name.to_owned()))?;
+
+        Ok(Self {
+            query: None,
+            target,
+            vector_candidates,
+            cached_sorted_docids: Default::default(),
+            limit,
+            distribution_shift,
+            embedder_index,
+        })
+    }
+
+    fn fill_buffer(
+        &mut self,
+        ctx: &mut SearchContext<'_>,
+        vector_candidates: &RoaringBitmap,
+    ) -> Result<()> {
+        let writer_index = (self.embedder_index as u16) << 8;
+        let readers: std::result::Result<Vec<_>, _> = (0..=u8::MAX)
+            .map_while(|k| {
+                arroy::Reader::open(ctx.txn, writer_index | (k as u16), ctx.index.vector_arroy)
+                    .map(Some)
+                    .or_else(|e| match e {
+                        arroy::Error::MissingMetadata => Ok(None),
+                        e => Err(e),
+                    })
+                    .transpose()
+            })
+            .collect();
+
+        let readers = readers?;
+
+        let target = &self.target;
+        let mut results = Vec::new();
+
+        for reader in readers.iter() {
+            let nns_by_vector =
+                reader.nns_by_vector(ctx.txn, target, self.limit, None, Some(vector_candidates))?;
+            let vectors: std::result::Result<Vec<_>, _> = nns_by_vector
+                .iter()
+                .map(|(docid, _)| reader.item_vector(ctx.txn, *docid).transpose().unwrap())
+                .collect();
+            let vectors = vectors?;
+            results.extend(nns_by_vector.into_iter().zip(vectors).map(|((x, y), z)| (x, y, z)));
+        }
+        results.sort_unstable_by_key(|(_, distance, _)| OrderedFloat(*distance));
+        self.cached_sorted_docids = results.into_iter();
+
+        Ok(())
+    }
+}
+
+impl<'ctx, Q: RankingRuleQueryTrait> RankingRule<'ctx, Q> for VectorSort<Q> {
+    fn id(&self) -> String {
+        "vector_sort".to_owned()
+    }
+
+    fn start_iteration(
+        &mut self,
+        ctx: &mut SearchContext<'ctx>,
+        _logger: &mut dyn SearchLogger<Q>,
+        universe: &RoaringBitmap,
+        query: &Q,
+    ) -> Result<()> {
+        assert!(self.query.is_none());
+
+        self.query = Some(query.clone());
+        let vector_candidates = &self.vector_candidates & universe;
+        self.fill_buffer(ctx, &vector_candidates)?;
+        Ok(())
+    }
+
+    #[allow(clippy::only_used_in_recursion)]
+    fn next_bucket(
+        &mut self,
+        ctx: &mut SearchContext<'ctx>,
+        _logger: &mut dyn SearchLogger<Q>,
+        universe: &RoaringBitmap,
+    ) -> Result<Option<RankingRuleOutput<Q>>> {
+        let query = self.query.as_ref().unwrap().clone();
+        let vector_candidates = &self.vector_candidates & universe;
+
+        if vector_candidates.is_empty() {
+            return Ok(Some(RankingRuleOutput {
+                query,
+                candidates: universe.clone(),
+                score: ScoreDetails::Vector(score_details::Vector {
+                    target_vector: self.target.clone(),
+                    value_similarity: None,
+                }),
+            }));
+        }
+
+        for (docid, distance, vector) in self.cached_sorted_docids.by_ref() {
+            if vector_candidates.contains(docid) {
+                let score = 1.0 - distance;
+                let score = self
+                    .distribution_shift
+                    .map(|distribution| distribution.shift(score))
+                    .unwrap_or(score);
+                return Ok(Some(RankingRuleOutput {
+                    query,
+                    candidates: RoaringBitmap::from_iter([docid]),
+                    score: ScoreDetails::Vector(score_details::Vector {
+                        target_vector: self.target.clone(),
+                        value_similarity: Some((vector, score)),
+                    }),
+                }));
+            }
+        }
+
+        // if we got out of this loop it means we've exhausted our cache.
+        // we need to refill it and run the function again.
+        self.fill_buffer(ctx, &vector_candidates)?;
+
+        // we tried filling the buffer, but it remained empty 😢
+        // it means we don't actually have any document remaining in the universe with a vector.
+        // => exit
+        if self.cached_sorted_docids.len() == 0 {
+            return Ok(Some(RankingRuleOutput {
+                query,
+                candidates: universe.clone(),
+                score: ScoreDetails::Vector(score_details::Vector {
+                    target_vector: self.target.clone(),
+                    value_similarity: None,
+                }),
+            }));
+        }
+
+        self.next_bucket(ctx, _logger, universe)
+    }
+
+    fn end_iteration(&mut self, _ctx: &mut SearchContext<'ctx>, _logger: &mut dyn SearchLogger<Q>) {
+        self.query = None;
+    }
+}

milli/src/update/clear_documents.rs

@@ -42,7 +42,8 @@ impl<'t, 'i> ClearDocuments<'t, 'i> {
             facet_id_is_empty_docids,
             field_id_docid_facet_f64s,
             field_id_docid_facet_strings,
-            vector_id_docid,
+            vector_arroy,
+            embedder_category_id: _,
             documents,
         } = self.index;
 
@@ -58,7 +59,6 @@ impl<'t, 'i> ClearDocuments<'t, 'i> {
         self.index.put_field_distribution(self.wtxn, &FieldDistribution::default())?;
         self.index.delete_geo_rtree(self.wtxn)?;
         self.index.delete_geo_faceted_documents_ids(self.wtxn)?;
-        self.index.delete_vector_hnsw(self.wtxn)?;
 
         // Clear the other databases.
         external_documents_ids.clear(self.wtxn)?;
@@ -82,7 +82,9 @@ impl<'t, 'i> ClearDocuments<'t, 'i> {
         facet_id_string_docids.clear(self.wtxn)?;
         field_id_docid_facet_f64s.clear(self.wtxn)?;
         field_id_docid_facet_strings.clear(self.wtxn)?;
-        vector_id_docid.clear(self.wtxn)?;
+        // vector
+        vector_arroy.clear(self.wtxn)?;
+
         documents.clear(self.wtxn)?;
 
         Ok(number_of_documents)

milli/src/update/index_documents/extract/extract_vector_points.rs

@@ -1,9 +1,10 @@
 use std::cmp::Ordering;
-use std::convert::TryFrom;
+use std::convert::{TryFrom, TryInto};
 use std::fs::File;
 use std::io::{self, BufReader, BufWriter};
 use std::mem::size_of;
 use std::str::from_utf8;
+use std::sync::Arc;
 
 use bytemuck::cast_slice;
 use grenad::Writer;
@@ -13,13 +14,56 @@ use serde_json::{from_slice, Value};
 
 use super::helpers::{create_writer, writer_into_reader, GrenadParameters};
 use crate::error::UserError;
+use crate::prompt::Prompt;
 use crate::update::del_add::{DelAdd, KvReaderDelAdd, KvWriterDelAdd};
 use crate::update::index_documents::helpers::try_split_at;
-use crate::{DocumentId, FieldId, InternalError, Result, VectorOrArrayOfVectors};
+use crate::vector::Embedder;
+use crate::{DocumentId, FieldsIdsMap, InternalError, Result, VectorOrArrayOfVectors};
 
 /// The length of the elements that are always in the buffer when inserting new values.
 const TRUNCATE_SIZE: usize = size_of::<DocumentId>();
 
+pub struct ExtractedVectorPoints {
+    // docid, _index -> KvWriterDelAdd -> Vector
+    pub manual_vectors: grenad::Reader<BufReader<File>>,
+    // docid -> ()
+    pub remove_vectors: grenad::Reader<BufReader<File>>,
+    // docid -> prompt
+    pub prompts: grenad::Reader<BufReader<File>>,
+}
+
+enum VectorStateDelta {
+    NoChange,
+    // Remove all vectors, generated or manual, from this document
+    NowRemoved,
+
+    // Add the manually specified vectors, passed in the other grenad
+    // Remove any previously generated vectors
+    // Note: changing the value of the manually specified vector **should not record** this delta
+    WasGeneratedNowManual(Vec<Vec<f32>>),
+
+    ManualDelta(Vec<Vec<f32>>, Vec<Vec<f32>>),
+
+    // Add the vector computed from the specified prompt
+    // Remove any previous vector
+    // Note: changing the value of the prompt **does require** recording this delta
+    NowGenerated(String),
+}
+
+impl VectorStateDelta {
+    fn into_values(self) -> (bool, String, (Vec<Vec<f32>>, Vec<Vec<f32>>)) {
+        match self {
+            VectorStateDelta::NoChange => Default::default(),
+            VectorStateDelta::NowRemoved => (true, Default::default(), Default::default()),
+            VectorStateDelta::WasGeneratedNowManual(add) => {
+                (true, Default::default(), (Default::default(), add))
+            }
+            VectorStateDelta::ManualDelta(del, add) => (false, Default::default(), (del, add)),
+            VectorStateDelta::NowGenerated(prompt) => (true, prompt, Default::default()),
+        }
+    }
+}
+
 /// Extracts the embedding vector contained in each document under the `_vectors` field.
 ///
 /// Returns the generated grenad reader containing the docid as key associated to the Vec<f32>
@@ -27,16 +71,35 @@ const TRUNCATE_SIZE: usize = size_of::<DocumentId>();
 pub fn extract_vector_points<R: io::Read + io::Seek>(
     obkv_documents: grenad::Reader<R>,
     indexer: GrenadParameters,
-    vectors_fid: FieldId,
+    field_id_map: &FieldsIdsMap,
-) -> Result<grenad::Reader<BufReader<File>>> {
+    prompt: &Prompt,
+    embedder_name: &str,
+) -> Result<ExtractedVectorPoints> {
     puffin::profile_function!();
 
-    let mut writer = create_writer(
+    // (docid, _index) -> KvWriterDelAdd -> Vector
+    let mut manual_vectors_writer = create_writer(
         indexer.chunk_compression_type,
         indexer.chunk_compression_level,
         tempfile::tempfile()?,
     );
 
+    // (docid) -> (prompt)
+    let mut prompts_writer = create_writer(
+        indexer.chunk_compression_type,
+        indexer.chunk_compression_level,
+        tempfile::tempfile()?,
+    );
+
+    // (docid) -> ()
+    let mut remove_vectors_writer = create_writer(
+        indexer.chunk_compression_type,
+        indexer.chunk_compression_level,
+        tempfile::tempfile()?,
+    );
+
+    let vectors_fid = field_id_map.id("_vectors");
+
     let mut key_buffer = Vec::new();
     let mut cursor = obkv_documents.into_cursor()?;
     while let Some((key, value)) = cursor.move_on_next()? {
@@ -53,43 +116,157 @@ pub fn extract_vector_points<R: io::Read + io::Seek>(
         // lazily get it when needed
         let document_id = || -> Value { from_utf8(external_id_bytes).unwrap().into() };
 
-        // first we retrieve the _vectors field
+        let vectors_field = vectors_fid
-        if let Some(value) = obkv.get(vectors_fid) {
+            .and_then(|vectors_fid| obkv.get(vectors_fid))
-            let vectors_obkv = KvReaderDelAdd::new(value);
+            .map(KvReaderDelAdd::new)
+            .map(|obkv| to_vector_maps(obkv, document_id))
+            .transpose()?;
 
-            // then we extract the values
+        let (del_map, add_map) = vectors_field.unzip();
-            let del_vectors = vectors_obkv
+        let del_map = del_map.flatten();
-                .get(DelAdd::Deletion)
+        let add_map = add_map.flatten();
-                .map(|vectors| extract_vectors(vectors, document_id))
-                .transpose()?
-                .flatten();
-            let add_vectors = vectors_obkv
-                .get(DelAdd::Addition)
-                .map(|vectors| extract_vectors(vectors, document_id))
-                .transpose()?
-                .flatten();
 
-            // and we finally push the unique vectors into the writer
+        let del_value = del_map.and_then(|mut map| map.remove(embedder_name));
-            push_vectors_diff(
+        let add_value = add_map.and_then(|mut map| map.remove(embedder_name));
-                &mut writer,
+
-                &mut key_buffer,
+        let delta = match (del_value, add_value) {
-                del_vectors.unwrap_or_default(),
+            (Some(old), Some(new)) => {
-                add_vectors.unwrap_or_default(),
+                // no autogeneration
-            )?;
+                let del_vectors = extract_vectors(old, document_id, embedder_name)?;
-        }
+                let add_vectors = extract_vectors(new, document_id, embedder_name)?;
+
+                if add_vectors.len() > u8::MAX.into() {
+                    return Err(crate::Error::UserError(crate::UserError::TooManyVectors(
+                        document_id().to_string(),
+                        add_vectors.len(),
+                    )));
+                }
+
+                VectorStateDelta::ManualDelta(del_vectors, add_vectors)
+            }
+            (Some(_old), None) => {
+                // Do we keep this document?
+                let document_is_kept = obkv
+                    .iter()
+                    .map(|(_, deladd)| KvReaderDelAdd::new(deladd))
+                    .any(|deladd| deladd.get(DelAdd::Addition).is_some());
+                if document_is_kept {
+                    // becomes autogenerated
+                    VectorStateDelta::NowGenerated(prompt.render(
+                        obkv,
+                        DelAdd::Addition,
+                        field_id_map,
+                    )?)
+                } else {
+                    VectorStateDelta::NowRemoved
+                }
+            }
+            (None, Some(new)) => {
+                // was possibly autogenerated, remove all vectors for that document
+                let add_vectors = extract_vectors(new, document_id, embedder_name)?;
+                if add_vectors.len() > u8::MAX.into() {
+                    return Err(crate::Error::UserError(crate::UserError::TooManyVectors(
+                        document_id().to_string(),
+                        add_vectors.len(),
+                    )));
+                }
+
+                VectorStateDelta::WasGeneratedNowManual(add_vectors)
+            }
+            (None, None) => {
+                // Do we keep this document?
+                let document_is_kept = obkv
+                    .iter()
+                    .map(|(_, deladd)| KvReaderDelAdd::new(deladd))
+                    .any(|deladd| deladd.get(DelAdd::Addition).is_some());
+
+                if document_is_kept {
+                    // Don't give up if the old prompt was failing
+                    let old_prompt =
+                        prompt.render(obkv, DelAdd::Deletion, field_id_map).unwrap_or_default();
+                    let new_prompt = prompt.render(obkv, DelAdd::Addition, field_id_map)?;
+                    if old_prompt != new_prompt {
+                        log::trace!(
+                            "🚀 Changing prompt from\n{old_prompt}\n===to===\n{new_prompt}"
+                        );
+                        VectorStateDelta::NowGenerated(new_prompt)
+                    } else {
+                        log::trace!("⏭️ Prompt unmodified, skipping");
+                        VectorStateDelta::NoChange
+                    }
+                } else {
+                    VectorStateDelta::NowRemoved
+                }
+            }
+        };
+
+        // and we finally push the unique vectors into the writer
+        push_vectors_diff(
+            &mut remove_vectors_writer,
+            &mut prompts_writer,
+            &mut manual_vectors_writer,
+            &mut key_buffer,
+            delta,
+        )?;
     }
 
-    writer_into_reader(writer)
+    Ok(ExtractedVectorPoints {
+        // docid, _index -> KvWriterDelAdd -> Vector
+        manual_vectors: writer_into_reader(manual_vectors_writer)?,
+        // docid -> ()
+        remove_vectors: writer_into_reader(remove_vectors_writer)?,
+        // docid -> prompt
+        prompts: writer_into_reader(prompts_writer)?,
+    })
+}
+
+fn to_vector_maps(
+    obkv: KvReaderDelAdd,
+    document_id: impl Fn() -> Value,
+) -> Result<(Option<serde_json::Map<String, Value>>, Option<serde_json::Map<String, Value>>)> {
+    let del = to_vector_map(obkv, DelAdd::Deletion, &document_id)?;
+    let add = to_vector_map(obkv, DelAdd::Addition, &document_id)?;
+    Ok((del, add))
+}
+
+fn to_vector_map(
+    obkv: KvReaderDelAdd,
+    side: DelAdd,
+    document_id: &impl Fn() -> Value,
+) -> Result<Option<serde_json::Map<String, Value>>> {
+    Ok(if let Some(value) = obkv.get(side) {
+        let Ok(value) = from_slice(value) else {
+            let value = from_slice(value).map_err(InternalError::SerdeJson)?;
+            return Err(crate::Error::UserError(UserError::InvalidVectorsMapType {
+                document_id: document_id(),
+                value,
+            }));
+        };
+        Some(value)
+    } else {
+        None
+    })
 }
 
 /// Computes the diff between both Del and Add numbers and
 /// only inserts the parts that differ in the sorter.
 fn push_vectors_diff(
-    writer: &mut Writer<BufWriter<File>>,
+    remove_vectors_writer: &mut Writer<BufWriter<File>>,
+    prompts_writer: &mut Writer<BufWriter<File>>,
+    manual_vectors_writer: &mut Writer<BufWriter<File>>,
     key_buffer: &mut Vec<u8>,
-    mut del_vectors: Vec<Vec<f32>>,
+    delta: VectorStateDelta,
-    mut add_vectors: Vec<Vec<f32>>,
 ) -> Result<()> {
+    let (must_remove, prompt, (mut del_vectors, mut add_vectors)) = delta.into_values();
+    if must_remove {
+        key_buffer.truncate(TRUNCATE_SIZE);
+        remove_vectors_writer.insert(&key_buffer, [])?;
+    }
+    if !prompt.is_empty() {
+        key_buffer.truncate(TRUNCATE_SIZE);
+        prompts_writer.insert(&key_buffer, prompt.as_bytes())?;
+    }
+
     // We sort and dedup the vectors
     del_vectors.sort_unstable_by(|a, b| compare_vectors(a, b));
     add_vectors.sort_unstable_by(|a, b| compare_vectors(a, b));
@@ -114,7 +291,7 @@ fn push_vectors_diff(
                 let mut obkv = KvWriterDelAdd::memory();
                 obkv.insert(DelAdd::Deletion, cast_slice(&vector))?;
                 let bytes = obkv.into_inner()?;
-                writer.insert(&key_buffer, bytes)?;
+                manual_vectors_writer.insert(&key_buffer, bytes)?;
             }
             EitherOrBoth::Right(vector) => {
                 // We insert only the Add part of the Obkv to inform
@@ -122,7 +299,7 @@ fn push_vectors_diff(
                 let mut obkv = KvWriterDelAdd::memory();
                 obkv.insert(DelAdd::Addition, cast_slice(&vector))?;
                 let bytes = obkv.into_inner()?;
-                writer.insert(&key_buffer, bytes)?;
+                manual_vectors_writer.insert(&key_buffer, bytes)?;
             }
         }
     }
@@ -136,13 +313,112 @@ fn compare_vectors(a: &[f32], b: &[f32]) -> Ordering {
 }
 
 /// Extracts the vectors from a JSON value.
-fn extract_vectors(value: &[u8], document_id: impl Fn() -> Value) -> Result<Option<Vec<Vec<f32>>>> {
+fn extract_vectors(
-    match from_slice(value) {
+    value: Value,
-        Ok(vectors) => Ok(VectorOrArrayOfVectors::into_array_of_vectors(vectors)),
+    document_id: impl Fn() -> Value,
+    name: &str,
+) -> Result<Vec<Vec<f32>>> {
+    // FIXME: ugly clone of the vectors here
+    match serde_json::from_value(value.clone()) {
+        Ok(vectors) => {
+            Ok(VectorOrArrayOfVectors::into_array_of_vectors(vectors).unwrap_or_default())
+        }
         Err(_) => Err(UserError::InvalidVectorsType {
             document_id: document_id(),
-            value: from_slice(value).map_err(InternalError::SerdeJson)?,
+            value,
+            subfield: name.to_owned(),
         }
         .into()),
     }
 }
+
+#[logging_timer::time]
+pub fn extract_embeddings<R: io::Read + io::Seek>(
+    // docid, prompt
+    prompt_reader: grenad::Reader<R>,
+    indexer: GrenadParameters,
+    embedder: Arc<Embedder>,
+) -> Result<grenad::Reader<BufReader<File>>> {
+    let rt = tokio::runtime::Builder::new_current_thread().enable_io().enable_time().build()?;
+
+    let n_chunks = embedder.chunk_count_hint(); // chunk level parellelism
+    let n_vectors_per_chunk = embedder.prompt_count_in_chunk_hint(); // number of vectors in a single chunk
+
+    // docid, state with embedding
+    let mut state_writer = create_writer(
+        indexer.chunk_compression_type,
+        indexer.chunk_compression_level,
+        tempfile::tempfile()?,
+    );
+
+    let mut chunks = Vec::with_capacity(n_chunks);
+    let mut current_chunk = Vec::with_capacity(n_vectors_per_chunk);
+    let mut current_chunk_ids = Vec::with_capacity(n_vectors_per_chunk);
+    let mut chunks_ids = Vec::with_capacity(n_chunks);
+    let mut cursor = prompt_reader.into_cursor()?;
+
+    while let Some((key, value)) = cursor.move_on_next()? {
+        let docid = key.try_into().map(DocumentId::from_be_bytes).unwrap();
+        // SAFETY: precondition, the grenad value was saved from a string
+        let prompt = unsafe { std::str::from_utf8_unchecked(value) };
+        if current_chunk.len() == current_chunk.capacity() {
+            chunks.push(std::mem::replace(
+                &mut current_chunk,
+                Vec::with_capacity(n_vectors_per_chunk),
+            ));
+            chunks_ids.push(std::mem::replace(
+                &mut current_chunk_ids,
+                Vec::with_capacity(n_vectors_per_chunk),
+            ));
+        };
+        current_chunk.push(prompt.to_owned());
+        current_chunk_ids.push(docid);
+
+        if chunks.len() == chunks.capacity() {
+            let chunked_embeds = rt
+                .block_on(
+                    embedder
+                        .embed_chunks(std::mem::replace(&mut chunks, Vec::with_capacity(n_chunks))),
+                )
+                .map_err(crate::vector::Error::from)
+                .map_err(crate::Error::from)?;
+
+            for (docid, embeddings) in chunks_ids
+                .iter()
+                .flat_map(|docids| docids.iter())
+                .zip(chunked_embeds.iter().flat_map(|embeds| embeds.iter()))
+            {
+                state_writer.insert(docid.to_be_bytes(), cast_slice(embeddings.as_inner()))?;
+            }
+            chunks_ids.clear();
+        }
+    }
+
+    // send last chunk
+    if !chunks.is_empty() {
+        let chunked_embeds = rt
+            .block_on(embedder.embed_chunks(std::mem::take(&mut chunks)))
+            .map_err(crate::vector::Error::from)
+            .map_err(crate::Error::from)?;
+        for (docid, embeddings) in chunks_ids
+            .iter()
+            .flat_map(|docids| docids.iter())
+            .zip(chunked_embeds.iter().flat_map(|embeds| embeds.iter()))
+        {
+            state_writer.insert(docid.to_be_bytes(), cast_slice(embeddings.as_inner()))?;
+        }
+    }
+
+    if !current_chunk.is_empty() {
+        let embeds = rt
+            .block_on(embedder.embed(std::mem::take(&mut current_chunk)))
+            .map_err(crate::vector::Error::from)
+            .map_err(crate::Error::from)?;
+
+        for (docid, embeddings) in current_chunk_ids.iter().zip(embeds.iter()) {
+            state_writer.insert(docid.to_be_bytes(), cast_slice(embeddings.as_inner()))?;
+        }
+    }
+
+    writer_into_reader(state_writer)
+}

milli/src/update/index_documents/extract/mod.rs

@@ -23,7 +23,9 @@ use self::extract_facet_string_docids::extract_facet_string_docids;
 use self::extract_fid_docid_facet_values::{extract_fid_docid_facet_values, ExtractedFacetValues};
 use self::extract_fid_word_count_docids::extract_fid_word_count_docids;
 use self::extract_geo_points::extract_geo_points;
-use self::extract_vector_points::extract_vector_points;
+use self::extract_vector_points::{
+    extract_embeddings, extract_vector_points, ExtractedVectorPoints,
+};
 use self::extract_word_docids::extract_word_docids;
 use self::extract_word_pair_proximity_docids::extract_word_pair_proximity_docids;
 use self::extract_word_position_docids::extract_word_position_docids;
@@ -33,7 +35,8 @@ use super::helpers::{
 };
 use super::{helpers, TypedChunk};
 use crate::proximity::ProximityPrecision;
-use crate::{FieldId, Result};
+use crate::vector::EmbeddingConfigs;
+use crate::{FieldId, FieldsIdsMap, Result};
 
 /// Extract data for each databases from obkv documents in parallel.
 /// Send data in grenad file over provided Sender.
@@ -47,13 +50,14 @@ pub(crate) fn data_from_obkv_documents(
     faceted_fields: HashSet<FieldId>,
     primary_key_id: FieldId,
     geo_fields_ids: Option<(FieldId, FieldId)>,
-    vectors_field_id: Option<FieldId>,
+    field_id_map: FieldsIdsMap,
     stop_words: Option<fst::Set<&[u8]>>,
     allowed_separators: Option<&[&str]>,
     dictionary: Option<&[&str]>,
     max_positions_per_attributes: Option<u32>,
     exact_attributes: HashSet<FieldId>,
     proximity_precision: ProximityPrecision,
+    embedders: EmbeddingConfigs,
 ) -> Result<()> {
     puffin::profile_function!();
 
@@ -64,7 +68,8 @@ pub(crate) fn data_from_obkv_documents(
                 original_documents_chunk,
                 indexer,
                 lmdb_writer_sx.clone(),
-                vectors_field_id,
+                field_id_map.clone(),
+                embedders.clone(),
             )
         })
         .collect::<Result<()>>()?;
@@ -276,24 +281,53 @@ fn send_original_documents_data(
     original_documents_chunk: Result<grenad::Reader<BufReader<File>>>,
     indexer: GrenadParameters,
     lmdb_writer_sx: Sender<Result<TypedChunk>>,
-    vectors_field_id: Option<FieldId>,
+    field_id_map: FieldsIdsMap,
+    embedders: EmbeddingConfigs,
 ) -> Result<()> {
     let original_documents_chunk =
         original_documents_chunk.and_then(|c| unsafe { as_cloneable_grenad(&c) })?;
 
-    if let Some(vectors_field_id) = vectors_field_id {
+    let documents_chunk_cloned = original_documents_chunk.clone();
-        let documents_chunk_cloned = original_documents_chunk.clone();
+    let lmdb_writer_sx_cloned = lmdb_writer_sx.clone();
-        let lmdb_writer_sx_cloned = lmdb_writer_sx.clone();
+    rayon::spawn(move || {
-        rayon::spawn(move || {
+        for (name, (embedder, prompt)) in embedders {
-            let result = extract_vector_points(documents_chunk_cloned, indexer, vectors_field_id);
+            let result = extract_vector_points(
-            let _ = match result {
+                documents_chunk_cloned.clone(),
-                Ok(vector_points) => {
+                indexer,
-                    lmdb_writer_sx_cloned.send(Ok(TypedChunk::VectorPoints(vector_points)))
+                &field_id_map,
+                &prompt,
+                &name,
+            );
+            match result {
+                Ok(ExtractedVectorPoints { manual_vectors, remove_vectors, prompts }) => {
+                    let embeddings = match extract_embeddings(prompts, indexer, embedder.clone()) {
+                        Ok(results) => Some(results),
+                        Err(error) => {
+                            let _ = lmdb_writer_sx_cloned.send(Err(error));
+                            None
+                        }
+                    };
+
+                    if !(remove_vectors.is_empty()
+                        && manual_vectors.is_empty()
+                        && embeddings.as_ref().map_or(true, |e| e.is_empty()))
+                    {
+                        let _ = lmdb_writer_sx_cloned.send(Ok(TypedChunk::VectorPoints {
+                            remove_vectors,
+                            embeddings,
+                            expected_dimension: embedder.dimensions(),
+                            manual_vectors,
+                            embedder_name: name,
+                        }));
+                    }
                 }
-                Err(error) => lmdb_writer_sx_cloned.send(Err(error)),
+
-            };
+                Err(error) => {
-        });
+                    let _ = lmdb_writer_sx_cloned.send(Err(error));
-    }
+                }
+            }
+        }
+    });
 
     // TODO: create a custom internal error
     lmdb_writer_sx.send(Ok(TypedChunk::Documents(original_documents_chunk))).unwrap();

milli/src/update/index_documents/mod.rs

@@ -4,7 +4,7 @@ mod helpers;
 mod transform;
 mod typed_chunk;
 
-use std::collections::HashSet;
+use std::collections::{HashMap, HashSet};
 use std::io::{Cursor, Read, Seek};
 use std::iter::FromIterator;
 use std::num::NonZeroU32;
@@ -14,6 +14,7 @@ use crossbeam_channel::{Receiver, Sender};
 use heed::types::Str;
 use heed::Database;
 use log::debug;
+use rand::SeedableRng;
 use roaring::RoaringBitmap;
 use serde::{Deserialize, Serialize};
 use slice_group_by::GroupBy;
@@ -36,6 +37,7 @@ pub use crate::update::index_documents::helpers::CursorClonableMmap;
 use crate::update::{
     IndexerConfig, UpdateIndexingStep, WordPrefixDocids, WordPrefixIntegerDocids, WordsPrefixesFst,
 };
+use crate::vector::EmbeddingConfigs;
 use crate::{CboRoaringBitmapCodec, Index, Result};
 
 static MERGED_DATABASE_COUNT: usize = 7;
@@ -78,6 +80,7 @@ pub struct IndexDocuments<'t, 'i, 'a, FP, FA> {
     should_abort: FA,
     added_documents: u64,
     deleted_documents: u64,
+    embedders: EmbeddingConfigs,
 }
 
 #[derive(Default, Debug, Clone)]
@@ -121,6 +124,7 @@ where
             index,
             added_documents: 0,
             deleted_documents: 0,
+            embedders: Default::default(),
         })
     }
 
@@ -167,6 +171,11 @@ where
         Ok((self, Ok(indexed_documents)))
     }
 
+    pub fn with_embedders(mut self, embedders: EmbeddingConfigs) -> Self {
+        self.embedders = embedders;
+        self
+    }
+
     /// Remove a batch of documents from the current builder.
     ///
     /// Returns the number of documents deleted from the builder.
@@ -322,17 +331,18 @@ where
         // get filterable fields for facet databases
         let faceted_fields = self.index.faceted_fields_ids(self.wtxn)?;
         // get the fid of the `_geo.lat` and `_geo.lng` fields.
-        let geo_fields_ids = match self.index.fields_ids_map(self.wtxn)?.id("_geo") {
+        let mut field_id_map = self.index.fields_ids_map(self.wtxn)?;
+
+        // self.index.fields_ids_map($a)? ==>> field_id_map
+        let geo_fields_ids = match field_id_map.id("_geo") {
             Some(gfid) => {
                 let is_sortable = self.index.sortable_fields_ids(self.wtxn)?.contains(&gfid);
                 let is_filterable = self.index.filterable_fields_ids(self.wtxn)?.contains(&gfid);
                 // if `_geo` is faceted then we get the `lat` and `lng`
                 if is_sortable || is_filterable {
-                    let field_ids = self
+                    let field_ids = field_id_map
-                        .index
-                        .fields_ids_map(self.wtxn)?
                         .insert("_geo.lat")
-                        .zip(self.index.fields_ids_map(self.wtxn)?.insert("_geo.lng"))
+                        .zip(field_id_map.insert("_geo.lng"))
                         .ok_or(UserError::AttributeLimitReached)?;
                     Some(field_ids)
                 } else {
@@ -341,8 +351,6 @@ where
             }
             None => None,
         };
-        // get the fid of the `_vectors` field.
-        let vectors_field_id = self.index.fields_ids_map(self.wtxn)?.id("_vectors");
 
         let stop_words = self.index.stop_words(self.wtxn)?;
         let separators = self.index.allowed_separators(self.wtxn)?;
@@ -364,6 +372,8 @@ where
             self.indexer_config.documents_chunk_size.unwrap_or(1024 * 1024 * 4); // 4MiB
         let max_positions_per_attributes = self.indexer_config.max_positions_per_attributes;
 
+        let cloned_embedder = self.embedders.clone();
+
         // Run extraction pipeline in parallel.
         pool.install(|| {
             puffin::profile_scope!("extract_and_send_grenad_chunks");
@@ -387,13 +397,14 @@ where
                     faceted_fields,
                     primary_key_id,
                     geo_fields_ids,
-                    vectors_field_id,
+                    field_id_map,
                     stop_words,
                     separators.as_deref(),
                     dictionary.as_deref(),
                     max_positions_per_attributes,
                     exact_attributes,
                     proximity_precision,
+                    cloned_embedder,
                 )
             });
 
@@ -402,7 +413,7 @@ where
             }
 
             // needs to be dropped to avoid channel waiting lock.
-            drop(lmdb_writer_sx)
+            drop(lmdb_writer_sx);
         });
 
         let index_is_empty = self.index.number_of_documents(self.wtxn)? == 0;
@@ -419,6 +430,8 @@ where
         let mut word_docids = None;
         let mut exact_word_docids = None;
 
+        let mut dimension = HashMap::new();
+
         for result in lmdb_writer_rx {
             if (self.should_abort)() {
                 return Err(Error::InternalError(InternalError::AbortedIndexation));
@@ -448,6 +461,22 @@ where
                     word_position_docids = Some(cloneable_chunk);
                     TypedChunk::WordPositionDocids(chunk)
                 }
+                TypedChunk::VectorPoints {
+                    expected_dimension,
+                    remove_vectors,
+                    embeddings,
+                    manual_vectors,
+                    embedder_name,
+                } => {
+                    dimension.insert(embedder_name.clone(), expected_dimension);
+                    TypedChunk::VectorPoints {
+                        remove_vectors,
+                        embeddings,
+                        expected_dimension,
+                        manual_vectors,
+                        embedder_name,
+                    }
+                }
                 otherwise => otherwise,
             };
 
@@ -480,6 +509,33 @@ where
         // We write the primary key field id into the main database
         self.index.put_primary_key(self.wtxn, &primary_key)?;
         let number_of_documents = self.index.number_of_documents(self.wtxn)?;
+        let mut rng = rand::rngs::StdRng::seed_from_u64(42);
+
+        for (embedder_name, dimension) in dimension {
+            let wtxn = &mut *self.wtxn;
+            let vector_arroy = self.index.vector_arroy;
+
+            let embedder_index = self.index.embedder_category_id.get(wtxn, &embedder_name)?.ok_or(
+                InternalError::DatabaseMissingEntry { db_name: "embedder_category_id", key: None },
+            )?;
+
+            pool.install(|| {
+                let writer_index = (embedder_index as u16) << 8;
+                for k in 0..=u8::MAX {
+                    let writer = arroy::Writer::prepare(
+                        wtxn,
+                        vector_arroy,
+                        writer_index | (k as u16),
+                        dimension,
+                    )?;
+                    if writer.is_empty(wtxn)? {
+                        break;
+                    }
+                    writer.build(wtxn, &mut rng, None)?;
+                }
+                Result::Ok(())
+            })?;
+        }
 
         self.execute_prefix_databases(
             word_docids,
@@ -694,6 +750,8 @@ fn execute_word_prefix_docids(
 
 #[cfg(test)]
 mod tests {
+    use std::collections::BTreeMap;
+
     use big_s::S;
     use fst::IntoStreamer;
     use heed::RwTxn;
@@ -703,6 +761,7 @@ mod tests {
     use crate::documents::documents_batch_reader_from_objects;
     use crate::index::tests::TempIndex;
     use crate::search::TermsMatchingStrategy;
+    use crate::update::Setting;
     use crate::{db_snap, Filter, Search};
 
     #[test]
@@ -2494,18 +2553,39 @@ mod tests {
     /// Vectors must be of the same length.
     #[test]
     fn test_multiple_vectors() {
+        use crate::vector::settings::{EmbedderSettings, EmbeddingSettings};
         let index = TempIndex::new();
 
-        index.add_documents(documents!([{"id": 0, "_vectors": [[0, 1, 2], [3, 4, 5]] }])).unwrap();
+        index
-        index.add_documents(documents!([{"id": 1, "_vectors": [6, 7, 8] }])).unwrap();
+            .update_settings(|settings| {
+                let mut embedders = BTreeMap::default();
+                embedders.insert(
+                    "manual".to_string(),
+                    Setting::Set(EmbeddingSettings {
+                        embedder_options: Setting::Set(EmbedderSettings::UserProvided(
+                            crate::vector::settings::UserProvidedSettings { dimensions: 3 },
+                        )),
+                        document_template: Setting::NotSet,
+                    }),
+                );
+                settings.set_embedder_settings(embedders);
+            })
+            .unwrap();
+
         index
             .add_documents(
-                documents!([{"id": 2, "_vectors": [[9, 10, 11], [12, 13, 14], [15, 16, 17]] }]),
+                documents!([{"id": 0, "_vectors": { "manual": [[0, 1, 2], [3, 4, 5]] } }]),
+            )
+            .unwrap();
+        index.add_documents(documents!([{"id": 1, "_vectors": { "manual": [6, 7, 8] }}])).unwrap();
+        index
+            .add_documents(
+                documents!([{"id": 2, "_vectors": { "manual": [[9, 10, 11], [12, 13, 14], [15, 16, 17]] }}]),
             )
             .unwrap();
 
         let rtxn = index.read_txn().unwrap();
-        let res = index.search(&rtxn).vector([0.0, 1.0, 2.0]).execute().unwrap();
+        let res = index.search(&rtxn).vector([0.0, 1.0, 2.0].to_vec()).execute().unwrap();
         assert_eq!(res.documents_ids.len(), 3);
     }
 

milli/src/update/index_documents/typed_chunk.rs

@@ -1,4 +1,4 @@
-use std::collections::{HashMap, HashSet};
+use std::collections::HashMap;
 use std::convert::TryInto;
 use std::fs::File;
 use std::io::{self, BufReader};
@@ -8,9 +8,7 @@ use charabia::{Language, Script};
 use grenad::MergerBuilder;
 use heed::types::Bytes;
 use heed::{PutFlags, RwTxn};
-use log::error;
 use obkv::{KvReader, KvWriter};
-use ordered_float::OrderedFloat;
 use roaring::RoaringBitmap;
 
 use super::helpers::{
@@ -18,16 +16,15 @@ use super::helpers::{
     valid_lmdb_key, CursorClonableMmap,
 };
 use super::{ClonableMmap, MergeFn};
-use crate::distance::NDotProductPoint;
-use crate::error::UserError;
 use crate::external_documents_ids::{DocumentOperation, DocumentOperationKind};
 use crate::facet::FacetType;
 use crate::index::db_name::DOCUMENTS;
-use crate::index::Hnsw;
 use crate::update::del_add::{deladd_serialize_add_side, DelAdd, KvReaderDelAdd};
 use crate::update::facet::FacetsUpdate;
 use crate::update::index_documents::helpers::{as_cloneable_grenad, try_split_array_at};
-use crate::{lat_lng_to_xyz, DocumentId, FieldId, GeoPoint, Index, Result, SerializationError};
+use crate::{
+    lat_lng_to_xyz, DocumentId, FieldId, GeoPoint, Index, InternalError, Result, SerializationError,
+};
 
 pub(crate) enum TypedChunk {
     FieldIdDocidFacetStrings(grenad::Reader<CursorClonableMmap>),
@@ -47,7 +44,13 @@ pub(crate) enum TypedChunk {
     FieldIdFacetIsNullDocids(grenad::Reader<BufReader<File>>),
     FieldIdFacetIsEmptyDocids(grenad::Reader<BufReader<File>>),
     GeoPoints(grenad::Reader<BufReader<File>>),
-    VectorPoints(grenad::Reader<BufReader<File>>),
+    VectorPoints {
+        remove_vectors: grenad::Reader<BufReader<File>>,
+        embeddings: Option<grenad::Reader<BufReader<File>>>,
+        expected_dimension: usize,
+        manual_vectors: grenad::Reader<BufReader<File>>,
+        embedder_name: String,
+    },
     ScriptLanguageDocids(HashMap<(Script, Language), (RoaringBitmap, RoaringBitmap)>),
 }
 
@@ -100,8 +103,8 @@ impl TypedChunk {
             TypedChunk::GeoPoints(grenad) => {
                 format!("GeoPoints {{ number_of_entries: {} }}", grenad.len())
             }
-            TypedChunk::VectorPoints(grenad) => {
+            TypedChunk::VectorPoints{ remove_vectors, manual_vectors, embeddings, expected_dimension, embedder_name } => {
-                format!("VectorPoints {{ number_of_entries: {} }}", grenad.len())
+                format!("VectorPoints {{ remove_vectors: {}, manual_vectors: {}, embeddings: {}, dimension: {}, embedder_name: {} }}", remove_vectors.len(), manual_vectors.len(), embeddings.as_ref().map(|e| e.len()).unwrap_or_default(), expected_dimension, embedder_name)
             }
             TypedChunk::ScriptLanguageDocids(sl_map) => {
                 format!("ScriptLanguageDocids {{ number_of_entries: {} }}", sl_map.len())
@@ -355,19 +358,77 @@ pub(crate) fn write_typed_chunk_into_index(
             index.put_geo_rtree(wtxn, &rtree)?;
             index.put_geo_faceted_documents_ids(wtxn, &geo_faceted_docids)?;
         }
-        TypedChunk::VectorPoints(vector_points) => {
+        TypedChunk::VectorPoints {
-            let mut vectors_set = HashSet::new();
+            remove_vectors,
-            // We extract and store the previous vectors
+            manual_vectors,
-            if let Some(hnsw) = index.vector_hnsw(wtxn)? {
+            embeddings,
-                for (pid, point) in hnsw.iter() {
+            expected_dimension,
-                    let pid_key = pid.into_inner();
+            embedder_name,
-                    let docid = index.vector_id_docid.get(wtxn, &pid_key)?.unwrap();
+        } => {
-                    let vector: Vec<_> = point.iter().copied().map(OrderedFloat).collect();
+            let embedder_index = index.embedder_category_id.get(wtxn, &embedder_name)?.ok_or(
-                    vectors_set.insert((docid, vector));
+                InternalError::DatabaseMissingEntry { db_name: "embedder_category_id", key: None },
+            )?;
+            let writer_index = (embedder_index as u16) << 8;
+            // FIXME: allow customizing distance
+            let writers: std::result::Result<Vec<_>, _> = (0..=u8::MAX)
+                .map(|k| {
+                    arroy::Writer::prepare(
+                        wtxn,
+                        index.vector_arroy,
+                        writer_index | (k as u16),
+                        expected_dimension,
+                    )
+                })
+                .collect();
+            let writers = writers?;
+
+            // remove vectors for docids we want them removed
+            let mut cursor = remove_vectors.into_cursor()?;
+            while let Some((key, _)) = cursor.move_on_next()? {
+                let docid = key.try_into().map(DocumentId::from_be_bytes).unwrap();
+
+                for writer in &writers {
+                    // Uses invariant: vectors are packed in the first writers.
+                    if !writer.del_item(wtxn, docid)? {
+                        break;
+                    }
                 }
             }
 
-            let mut cursor = vector_points.into_cursor()?;
+            // add generated embeddings
+            if let Some(embeddings) = embeddings {
+                let mut cursor = embeddings.into_cursor()?;
+                while let Some((key, value)) = cursor.move_on_next()? {
+                    let docid = key.try_into().map(DocumentId::from_be_bytes).unwrap();
+                    let data = pod_collect_to_vec(value);
+                    // it is a code error to have embeddings and not expected_dimension
+                    let embeddings =
+                        crate::vector::Embeddings::from_inner(data, expected_dimension)
+                            // code error if we somehow got the wrong dimension
+                            .unwrap();
+
+                    if embeddings.embedding_count() > u8::MAX.into() {
+                        let external_docid = if let Ok(Some(Ok(index))) = index
+                            .external_id_of(wtxn, std::iter::once(docid))
+                            .map(|it| it.into_iter().next())
+                        {
+                            index
+                        } else {
+                            format!("internal docid={docid}")
+                        };
+                        return Err(crate::Error::UserError(crate::UserError::TooManyVectors(
+                            external_docid,
+                            embeddings.embedding_count(),
+                        )));
+                    }
+                    for (embedding, writer) in embeddings.iter().zip(&writers) {
+                        writer.add_item(wtxn, docid, embedding)?;
+                    }
+                }
+            }
+
+            // perform the manual diff
+            let mut cursor = manual_vectors.into_cursor()?;
             while let Some((key, value)) = cursor.move_on_next()? {
                 // convert the key back to a u32 (4 bytes)
                 let (left, _index) = try_split_array_at(key).unwrap();
@@ -375,58 +436,52 @@ pub(crate) fn write_typed_chunk_into_index(
 
                 let vector_deladd_obkv = KvReaderDelAdd::new(value);
                 if let Some(value) = vector_deladd_obkv.get(DelAdd::Deletion) {
-                    // convert the vector back to a Vec<f32>
+                    let vector: Vec<f32> = pod_collect_to_vec(value);
-                    let vector = pod_collect_to_vec(value).into_iter().map(OrderedFloat).collect();
+
-                    let key = (docid, vector);
+                    let mut deleted_index = None;
-                    if !vectors_set.remove(&key) {
+                    for (index, writer) in writers.iter().enumerate() {
-                        error!("Unable to delete the vector: {:?}", key.1);
+                        let Some(candidate) = writer.item_vector(wtxn, docid)? else {
+                            // uses invariant: vectors are packed in the first writers.
+                            break;
+                        };
+                        if candidate == vector {
+                            writer.del_item(wtxn, docid)?;
+                            deleted_index = Some(index);
+                        }
+                    }
+
+                    // 🥲 enforce invariant: vectors are packed in the first writers.
+                    if let Some(deleted_index) = deleted_index {
+                        let mut last_index_with_a_vector = None;
+                        for (index, writer) in writers.iter().enumerate().skip(deleted_index) {
+                            let Some(candidate) = writer.item_vector(wtxn, docid)? else {
+                                break;
+                            };
+                            last_index_with_a_vector = Some((index, candidate));
+                        }
+                        if let Some((last_index, vector)) = last_index_with_a_vector {
+                            // unwrap: computed the index from the list of writers
+                            let writer = writers.get(last_index).unwrap();
+                            writer.del_item(wtxn, docid)?;
+                            writers.get(deleted_index).unwrap().add_item(wtxn, docid, &vector)?;
+                        }
                     }
                 }
+
                 if let Some(value) = vector_deladd_obkv.get(DelAdd::Addition) {
-                    // convert the vector back to a Vec<f32>
+                    let vector = pod_collect_to_vec(value);
-                    let vector = pod_collect_to_vec(value).into_iter().map(OrderedFloat).collect();
-                    vectors_set.insert((docid, vector));
-                }
-            }
 
-            // Extract the most common vector dimension
+                    // overflow was detected during vector extraction.
-            let expected_dimension_size = {
+                    for writer in &writers {
-                let mut dims = HashMap::new();
+                        if !writer.contains_item(wtxn, docid)? {
-                vectors_set.iter().for_each(|(_, v)| *dims.entry(v.len()).or_insert(0) += 1);
+                            writer.add_item(wtxn, docid, &vector)?;
-                dims.into_iter().max_by_key(|(_, count)| *count).map(|(len, _)| len)
+                            break;
-            };
+                        }
-
-            // Ensure that the vector lengths are correct and
-            // prepare the vectors before inserting them in the HNSW.
-            let mut points = Vec::new();
-            let mut docids = Vec::new();
-            for (docid, vector) in vectors_set {
-                if expected_dimension_size.map_or(false, |expected| expected != vector.len()) {
-                    return Err(UserError::InvalidVectorDimensions {
-                        expected: expected_dimension_size.unwrap_or(vector.len()),
-                        found: vector.len(),
                     }
-                    .into());
-                } else {
-                    let vector = vector.into_iter().map(OrderedFloat::into_inner).collect();
-                    points.push(NDotProductPoint::new(vector));
-                    docids.push(docid);
                 }
             }
 
-            let hnsw_length = points.len();
+            log::debug!("Finished vector chunk for {}", embedder_name);
-            let (new_hnsw, pids) = Hnsw::builder().build_hnsw(points);
-
-            assert_eq!(docids.len(), pids.len());
-
-            // Store the vectors in the point-docid relation database
-            index.vector_id_docid.clear(wtxn)?;
-            for (docid, pid) in docids.into_iter().zip(pids) {
-                index.vector_id_docid.put(wtxn, &pid.into_inner(), &docid)?;
-            }
-
-            log::debug!("There are {} entries in the HNSW so far", hnsw_length);
-            index.put_vector_hnsw(wtxn, &new_hnsw)?;
         }
         TypedChunk::ScriptLanguageDocids(sl_map) => {
             for (key, (deletion, addition)) in sl_map {

milli/src/update/settings.rs

@@ -1,9 +1,11 @@
 use std::collections::{BTreeMap, BTreeSet, HashMap, HashSet};
+use std::convert::TryInto;
 use std::result::Result as StdResult;
+use std::sync::Arc;
 
 use charabia::{Normalize, Tokenizer, TokenizerBuilder};
 use deserr::{DeserializeError, Deserr};
-use itertools::Itertools;
+use itertools::{EitherOrBoth, Itertools};
 use serde::{Deserialize, Deserializer, Serialize, Serializer};
 use time::OffsetDateTime;
 
@@ -15,6 +17,8 @@ use crate::index::{DEFAULT_MIN_WORD_LEN_ONE_TYPO, DEFAULT_MIN_WORD_LEN_TWO_TYPOS
 use crate::proximity::ProximityPrecision;
 use crate::update::index_documents::IndexDocumentsMethod;
 use crate::update::{IndexDocuments, UpdateIndexingStep};
+use crate::vector::settings::{EmbeddingSettings, PromptSettings};
+use crate::vector::{Embedder, EmbeddingConfig, EmbeddingConfigs};
 use crate::{FieldsIdsMap, Index, OrderBy, Result};
 
 #[derive(Debug, Clone, PartialEq, Eq, Copy)]
@@ -73,6 +77,13 @@ impl<T> Setting<T> {
             otherwise => otherwise,
         }
     }
+
+    pub fn apply(&mut self, new: Self) {
+        if let Setting::NotSet = new {
+            return;
+        }
+        *self = new;
+    }
 }
 
 impl<T: Serialize> Serialize for Setting<T> {
@@ -129,6 +140,7 @@ pub struct Settings<'a, 't, 'i> {
     sort_facet_values_by: Setting<HashMap<String, OrderBy>>,
     pagination_max_total_hits: Setting<usize>,
     proximity_precision: Setting<ProximityPrecision>,
+    embedder_settings: Setting<BTreeMap<String, Setting<EmbeddingSettings>>>,
 }
 
 impl<'a, 't, 'i> Settings<'a, 't, 'i> {
@@ -161,6 +173,7 @@ impl<'a, 't, 'i> Settings<'a, 't, 'i> {
             sort_facet_values_by: Setting::NotSet,
             pagination_max_total_hits: Setting::NotSet,
             proximity_precision: Setting::NotSet,
+            embedder_settings: Setting::NotSet,
             indexer_config,
         }
     }
@@ -343,6 +356,14 @@ impl<'a, 't, 'i> Settings<'a, 't, 'i> {
         self.proximity_precision = Setting::Reset;
     }
 
+    pub fn set_embedder_settings(&mut self, value: BTreeMap<String, Setting<EmbeddingSettings>>) {
+        self.embedder_settings = Setting::Set(value);
+    }
+
+    pub fn reset_embedder_settings(&mut self) {
+        self.embedder_settings = Setting::Reset;
+    }
+
     fn reindex<FP, FA>(
         &mut self,
         progress_callback: &FP,
@@ -377,6 +398,9 @@ impl<'a, 't, 'i> Settings<'a, 't, 'i> {
             fields_ids_map,
         )?;
 
+        let embedder_configs = self.index.embedding_configs(self.wtxn)?;
+        let embedders = self.embedders(embedder_configs)?;
+
         // We index the generated `TransformOutput` which must contain
         // all the documents with fields in the newly defined searchable order.
         let indexing_builder = IndexDocuments::new(
@@ -387,11 +411,33 @@ impl<'a, 't, 'i> Settings<'a, 't, 'i> {
             &progress_callback,
             &should_abort,
         )?;
+
+        let indexing_builder = indexing_builder.with_embedders(embedders);
         indexing_builder.execute_raw(output)?;
 
         Ok(())
     }
 
+    fn embedders(
+        &self,
+        embedding_configs: Vec<(String, EmbeddingConfig)>,
+    ) -> Result<EmbeddingConfigs> {
+        let res: Result<_> = embedding_configs
+            .into_iter()
+            .map(|(name, EmbeddingConfig { embedder_options, prompt })| {
+                let prompt = Arc::new(prompt.try_into().map_err(crate::Error::from)?);
+
+                let embedder = Arc::new(
+                    Embedder::new(embedder_options.clone())
+                        .map_err(crate::vector::Error::from)
+                        .map_err(crate::Error::from)?,
+                );
+                Ok((name, (embedder, prompt)))
+            })
+            .collect();
+        res.map(EmbeddingConfigs::new)
+    }
+
     fn update_displayed(&mut self) -> Result<bool> {
         match self.displayed_fields {
             Setting::Set(ref fields) => {
@@ -890,6 +936,73 @@ impl<'a, 't, 'i> Settings<'a, 't, 'i> {
         Ok(changed)
     }
 
+    fn update_embedding_configs(&mut self) -> Result<bool> {
+        let update = match std::mem::take(&mut self.embedder_settings) {
+            Setting::Set(configs) => {
+                let mut changed = false;
+                let old_configs = self.index.embedding_configs(self.wtxn)?;
+                let old_configs: BTreeMap<String, Setting<EmbeddingSettings>> =
+                    old_configs.into_iter().map(|(k, v)| (k, Setting::Set(v.into()))).collect();
+
+                let mut new_configs = BTreeMap::new();
+                for joined in old_configs
+                    .into_iter()
+                    .merge_join_by(configs.into_iter(), |(left, _), (right, _)| left.cmp(right))
+                {
+                    match joined {
+                        EitherOrBoth::Both((name, mut old), (_, new)) => {
+                            old.apply(new);
+                            let new = validate_prompt(&name, old)?;
+                            changed = true;
+                            new_configs.insert(name, new);
+                        }
+                        EitherOrBoth::Left((name, setting)) => {
+                            new_configs.insert(name, setting);
+                        }
+                        EitherOrBoth::Right((name, setting)) => {
+                            let setting = validate_prompt(&name, setting)?;
+                            changed = true;
+                            new_configs.insert(name, setting);
+                        }
+                    }
+                }
+                let new_configs: Vec<(String, EmbeddingConfig)> = new_configs
+                    .into_iter()
+                    .filter_map(|(name, setting)| match setting {
+                        Setting::Set(value) => Some((name, value.into())),
+                        Setting::Reset => None,
+                        Setting::NotSet => Some((name, EmbeddingSettings::default().into())),
+                    })
+                    .collect();
+
+                self.index.embedder_category_id.clear(self.wtxn)?;
+                for (index, (embedder_name, _)) in new_configs.iter().enumerate() {
+                    self.index.embedder_category_id.put_with_flags(
+                        self.wtxn,
+                        heed::PutFlags::APPEND,
+                        embedder_name,
+                        &index
+                            .try_into()
+                            .map_err(|_| UserError::TooManyEmbedders(new_configs.len()))?,
+                    )?;
+                }
+
+                if new_configs.is_empty() {
+                    self.index.delete_embedding_configs(self.wtxn)?;
+                } else {
+                    self.index.put_embedding_configs(self.wtxn, new_configs)?;
+                }
+                changed
+            }
+            Setting::Reset => {
+                self.index.delete_embedding_configs(self.wtxn)?;
+                true
+            }
+            Setting::NotSet => false,
+        };
+        Ok(update)
+    }
+
     pub fn execute<FP, FA>(mut self, progress_callback: FP, should_abort: FA) -> Result<()>
     where
         FP: Fn(UpdateIndexingStep) + Sync,
@@ -927,6 +1040,13 @@ impl<'a, 't, 'i> Settings<'a, 't, 'i> {
         let searchable_updated = self.update_searchable()?;
         let exact_attributes_updated = self.update_exact_attributes()?;
         let proximity_precision = self.update_proximity_precision()?;
+        // TODO: very rough approximation of the needs for reindexing where any change will result in
+        // a full reindexing.
+        // What can be done instead:
+        // 1. Only change the distance on a distance change
+        // 2. Only change the name -> embedder mapping on a name change
+        // 3. Keep the old vectors but reattempt indexing on a prompt change: only actually changed prompt will need embedding + storage
+        let embedding_configs_updated = self.update_embedding_configs()?;
 
         if stop_words_updated
             || non_separator_tokens_updated
@@ -937,6 +1057,7 @@ impl<'a, 't, 'i> Settings<'a, 't, 'i> {
             || searchable_updated
             || exact_attributes_updated
             || proximity_precision
+            || embedding_configs_updated
         {
             self.reindex(&progress_callback, &should_abort, old_fields_ids_map)?;
         }
@@ -945,6 +1066,31 @@ impl<'a, 't, 'i> Settings<'a, 't, 'i> {
     }
 }
 
+fn validate_prompt(
+    name: &str,
+    new: Setting<EmbeddingSettings>,
+) -> Result<Setting<EmbeddingSettings>> {
+    match new {
+        Setting::Set(EmbeddingSettings {
+            embedder_options,
+            document_template: Setting::Set(PromptSettings { template: Setting::Set(template) }),
+        }) => {
+            // validate
+            let template = crate::prompt::Prompt::new(template)
+                .map(|prompt| crate::prompt::PromptData::from(prompt).template)
+                .map_err(|inner| UserError::InvalidPromptForEmbeddings(name.to_owned(), inner))?;
+
+            Ok(Setting::Set(EmbeddingSettings {
+                embedder_options,
+                document_template: Setting::Set(PromptSettings {
+                    template: Setting::Set(template),
+                }),
+            }))
+        }
+        new => Ok(new),
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use big_s::S;
@@ -1763,6 +1909,7 @@ mod tests {
                     sort_facet_values_by,
                     pagination_max_total_hits,
                     proximity_precision,
+                    embedder_settings,
                 } = settings;
                 assert!(matches!(searchable_fields, Setting::NotSet));
                 assert!(matches!(displayed_fields, Setting::NotSet));
@@ -1785,6 +1932,7 @@ mod tests {
                 assert!(matches!(sort_facet_values_by, Setting::NotSet));
                 assert!(matches!(pagination_max_total_hits, Setting::NotSet));
                 assert!(matches!(proximity_precision, Setting::NotSet));
+                assert!(matches!(embedder_settings, Setting::NotSet));
             })
             .unwrap();
     }

milli/src/vector/error.rs

@@ -0,0 +1,244 @@
+use std::path::PathBuf;
+
+use hf_hub::api::sync::ApiError;
+
+use crate::error::FaultSource;
+use crate::vector::openai::OpenAiError;
+
+#[derive(Debug, thiserror::Error)]
+#[error("Error while generating embeddings: {inner}")]
+pub struct Error {
+    pub inner: Box<ErrorKind>,
+}
+
+impl<I: Into<ErrorKind>> From<I> for Error {
+    fn from(value: I) -> Self {
+        Self { inner: Box::new(value.into()) }
+    }
+}
+
+impl Error {
+    pub fn fault(&self) -> FaultSource {
+        match &*self.inner {
+            ErrorKind::NewEmbedderError(inner) => inner.fault,
+            ErrorKind::EmbedError(inner) => inner.fault,
+        }
+    }
+}
+
+#[derive(Debug, thiserror::Error)]
+pub enum ErrorKind {
+    #[error(transparent)]
+    NewEmbedderError(#[from] NewEmbedderError),
+    #[error(transparent)]
+    EmbedError(#[from] EmbedError),
+}
+
+#[derive(Debug, thiserror::Error)]
+#[error("{fault}: {kind}")]
+pub struct EmbedError {
+    pub kind: EmbedErrorKind,
+    pub fault: FaultSource,
+}
+
+#[derive(Debug, thiserror::Error)]
+pub enum EmbedErrorKind {
+    #[error("could not tokenize: {0}")]
+    Tokenize(Box<dyn std::error::Error + Send + Sync>),
+    #[error("unexpected tensor shape: {0}")]
+    TensorShape(candle_core::Error),
+    #[error("unexpected tensor value: {0}")]
+    TensorValue(candle_core::Error),
+    #[error("could not run model: {0}")]
+    ModelForward(candle_core::Error),
+    #[error("could not reach OpenAI: {0}")]
+    OpenAiNetwork(reqwest::Error),
+    #[error("unexpected response from OpenAI: {0}")]
+    OpenAiUnexpected(reqwest::Error),
+    #[error("could not authenticate against OpenAI: {0}")]
+    OpenAiAuth(OpenAiError),
+    #[error("sent too many requests to OpenAI: {0}")]
+    OpenAiTooManyRequests(OpenAiError),
+    #[error("received internal error from OpenAI: {0}")]
+    OpenAiInternalServerError(OpenAiError),
+    #[error("sent too many tokens in a request to OpenAI: {0}")]
+    OpenAiTooManyTokens(OpenAiError),
+    #[error("received unhandled HTTP status code {0} from OpenAI")]
+    OpenAiUnhandledStatusCode(u16),
+    #[error("attempt to embed the following text in a configuration where embeddings must be user provided: {0:?}")]
+    ManualEmbed(String),
+}
+
+impl EmbedError {
+    pub fn tokenize(inner: Box<dyn std::error::Error + Send + Sync>) -> Self {
+        Self { kind: EmbedErrorKind::Tokenize(inner), fault: FaultSource::Runtime }
+    }
+
+    pub fn tensor_shape(inner: candle_core::Error) -> Self {
+        Self { kind: EmbedErrorKind::TensorShape(inner), fault: FaultSource::Bug }
+    }
+
+    pub fn tensor_value(inner: candle_core::Error) -> Self {
+        Self { kind: EmbedErrorKind::TensorValue(inner), fault: FaultSource::Bug }
+    }
+
+    pub fn model_forward(inner: candle_core::Error) -> Self {
+        Self { kind: EmbedErrorKind::ModelForward(inner), fault: FaultSource::Runtime }
+    }
+
+    pub fn openai_network(inner: reqwest::Error) -> Self {
+        Self { kind: EmbedErrorKind::OpenAiNetwork(inner), fault: FaultSource::Runtime }
+    }
+
+    pub fn openai_unexpected(inner: reqwest::Error) -> EmbedError {
+        Self { kind: EmbedErrorKind::OpenAiUnexpected(inner), fault: FaultSource::Bug }
+    }
+
+    pub(crate) fn openai_auth_error(inner: OpenAiError) -> EmbedError {
+        Self { kind: EmbedErrorKind::OpenAiAuth(inner), fault: FaultSource::User }
+    }
+
+    pub(crate) fn openai_too_many_requests(inner: OpenAiError) -> EmbedError {
+        Self { kind: EmbedErrorKind::OpenAiTooManyRequests(inner), fault: FaultSource::Runtime }
+    }
+
+    pub(crate) fn openai_internal_server_error(inner: OpenAiError) -> EmbedError {
+        Self { kind: EmbedErrorKind::OpenAiInternalServerError(inner), fault: FaultSource::Runtime }
+    }
+
+    pub(crate) fn openai_too_many_tokens(inner: OpenAiError) -> EmbedError {
+        Self { kind: EmbedErrorKind::OpenAiTooManyTokens(inner), fault: FaultSource::Bug }
+    }
+
+    pub(crate) fn openai_unhandled_status_code(code: u16) -> EmbedError {
+        Self { kind: EmbedErrorKind::OpenAiUnhandledStatusCode(code), fault: FaultSource::Bug }
+    }
+
+    pub(crate) fn embed_on_manual_embedder(texts: String) -> EmbedError {
+        Self { kind: EmbedErrorKind::ManualEmbed(texts), fault: FaultSource::User }
+    }
+}
+
+#[derive(Debug, thiserror::Error)]
+#[error("{fault}: {kind}")]
+pub struct NewEmbedderError {
+    pub kind: NewEmbedderErrorKind,
+    pub fault: FaultSource,
+}
+
+impl NewEmbedderError {
+    pub fn open_config(config_filename: PathBuf, inner: std::io::Error) -> NewEmbedderError {
+        let open_config = OpenConfig { filename: config_filename, inner };
+
+        Self { kind: NewEmbedderErrorKind::OpenConfig(open_config), fault: FaultSource::Runtime }
+    }
+
+    pub fn deserialize_config(
+        config: String,
+        config_filename: PathBuf,
+        inner: serde_json::Error,
+    ) -> NewEmbedderError {
+        let deserialize_config = DeserializeConfig { config, filename: config_filename, inner };
+        Self {
+            kind: NewEmbedderErrorKind::DeserializeConfig(deserialize_config),
+            fault: FaultSource::Runtime,
+        }
+    }
+
+    pub fn open_tokenizer(
+        tokenizer_filename: PathBuf,
+        inner: Box<dyn std::error::Error + Send + Sync>,
+    ) -> NewEmbedderError {
+        let open_tokenizer = OpenTokenizer { filename: tokenizer_filename, inner };
+        Self {
+            kind: NewEmbedderErrorKind::OpenTokenizer(open_tokenizer),
+            fault: FaultSource::Runtime,
+        }
+    }
+
+    pub fn new_api_fail(inner: ApiError) -> Self {
+        Self { kind: NewEmbedderErrorKind::NewApiFail(inner), fault: FaultSource::Bug }
+    }
+
+    pub fn api_get(inner: ApiError) -> Self {
+        Self { kind: NewEmbedderErrorKind::ApiGet(inner), fault: FaultSource::Undecided }
+    }
+
+    pub fn pytorch_weight(inner: candle_core::Error) -> Self {
+        Self { kind: NewEmbedderErrorKind::PytorchWeight(inner), fault: FaultSource::Runtime }
+    }
+
+    pub fn safetensor_weight(inner: candle_core::Error) -> Self {
+        Self { kind: NewEmbedderErrorKind::PytorchWeight(inner), fault: FaultSource::Runtime }
+    }
+
+    pub fn load_model(inner: candle_core::Error) -> Self {
+        Self { kind: NewEmbedderErrorKind::LoadModel(inner), fault: FaultSource::Runtime }
+    }
+
+    pub fn hf_could_not_determine_dimension(inner: EmbedError) -> NewEmbedderError {
+        Self {
+            kind: NewEmbedderErrorKind::CouldNotDetermineDimension(inner),
+            fault: FaultSource::Runtime,
+        }
+    }
+
+    pub fn openai_initialize_web_client(inner: reqwest::Error) -> Self {
+        Self { kind: NewEmbedderErrorKind::InitWebClient(inner), fault: FaultSource::Runtime }
+    }
+
+    pub fn openai_invalid_api_key_format(inner: reqwest::header::InvalidHeaderValue) -> Self {
+        Self { kind: NewEmbedderErrorKind::InvalidApiKeyFormat(inner), fault: FaultSource::User }
+    }
+}
+
+#[derive(Debug, thiserror::Error)]
+#[error("could not open config at {filename:?}: {inner}")]
+pub struct OpenConfig {
+    pub filename: PathBuf,
+    pub inner: std::io::Error,
+}
+
+#[derive(Debug, thiserror::Error)]
+#[error("could not deserialize config at {filename}: {inner}. Config follows:\n{config}")]
+pub struct DeserializeConfig {
+    pub config: String,
+    pub filename: PathBuf,
+    pub inner: serde_json::Error,
+}
+
+#[derive(Debug, thiserror::Error)]
+#[error("could not open tokenizer at {filename}: {inner}")]
+pub struct OpenTokenizer {
+    pub filename: PathBuf,
+    #[source]
+    pub inner: Box<dyn std::error::Error + Send + Sync>,
+}
+
+#[derive(Debug, thiserror::Error)]
+pub enum NewEmbedderErrorKind {
+    // hf
+    #[error(transparent)]
+    OpenConfig(OpenConfig),
+    #[error(transparent)]
+    DeserializeConfig(DeserializeConfig),
+    #[error(transparent)]
+    OpenTokenizer(OpenTokenizer),
+    #[error("could not build weights from Pytorch weights: {0}")]
+    PytorchWeight(candle_core::Error),
+    #[error("could not build weights from Safetensor weights: {0}")]
+    SafetensorWeight(candle_core::Error),
+    #[error("could not spawn HG_HUB API client: {0}")]
+    NewApiFail(ApiError),
+    #[error("fetching file from HG_HUB failed: {0}")]
+    ApiGet(ApiError),
+    #[error("could not determine model dimensions: test embedding failed with {0}")]
+    CouldNotDetermineDimension(EmbedError),
+    #[error("loading model failed: {0}")]
+    LoadModel(candle_core::Error),
+    // openai
+    #[error("initializing web client for sending embedding requests failed: {0}")]
+    InitWebClient(reqwest::Error),
+    #[error("The API key passed to Authorization error was in an invalid format: {0}")]
+    InvalidApiKeyFormat(reqwest::header::InvalidHeaderValue),
+}

milli/src/vector/hf.rs

@@ -0,0 +1,195 @@
+use candle_core::Tensor;
+use candle_nn::VarBuilder;
+use candle_transformers::models::bert::{BertModel, Config, DTYPE};
+// FIXME: currently we'll be using the hub to retrieve model, in the future we might want to embed it into Meilisearch itself
+use hf_hub::api::sync::Api;
+use hf_hub::{Repo, RepoType};
+use tokenizers::{PaddingParams, Tokenizer};
+
+pub use super::error::{EmbedError, Error, NewEmbedderError};
+use super::{DistributionShift, Embedding, Embeddings};
+
+#[derive(
+    Debug,
+    Clone,
+    Copy,
+    Default,
+    Hash,
+    PartialEq,
+    Eq,
+    serde::Deserialize,
+    serde::Serialize,
+    deserr::Deserr,
+)]
+#[serde(deny_unknown_fields, rename_all = "camelCase")]
+#[deserr(rename_all = camelCase, deny_unknown_fields)]
+enum WeightSource {
+    #[default]
+    Safetensors,
+    Pytorch,
+}
+
+#[derive(Debug, Clone, Hash, PartialEq, Eq, serde::Deserialize, serde::Serialize)]
+pub struct EmbedderOptions {
+    pub model: String,
+    pub revision: Option<String>,
+}
+
+impl EmbedderOptions {
+    pub fn new() -> Self {
+        Self {
+            model: "BAAI/bge-base-en-v1.5".to_string(),
+            revision: Some("617ca489d9e86b49b8167676d8220688b99db36e".into()),
+        }
+    }
+}
+
+impl Default for EmbedderOptions {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+/// Perform embedding of documents and queries
+pub struct Embedder {
+    model: BertModel,
+    tokenizer: Tokenizer,
+    options: EmbedderOptions,
+    dimensions: usize,
+}
+
+impl std::fmt::Debug for Embedder {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("Embedder")
+            .field("model", &self.options.model)
+            .field("tokenizer", &self.tokenizer)
+            .field("options", &self.options)
+            .finish()
+    }
+}
+
+impl Embedder {
+    pub fn new(options: EmbedderOptions) -> std::result::Result<Self, NewEmbedderError> {
+        let device = candle_core::Device::Cpu;
+        let repo = match options.revision.clone() {
+            Some(revision) => Repo::with_revision(options.model.clone(), RepoType::Model, revision),
+            None => Repo::model(options.model.clone()),
+        };
+        let (config_filename, tokenizer_filename, weights_filename, weight_source) = {
+            let api = Api::new().map_err(NewEmbedderError::new_api_fail)?;
+            let api = api.repo(repo);
+            let config = api.get("config.json").map_err(NewEmbedderError::api_get)?;
+            let tokenizer = api.get("tokenizer.json").map_err(NewEmbedderError::api_get)?;
+            let (weights, source) = {
+                api.get("pytorch_model.bin")
+                    .map(|filename| (filename, WeightSource::Pytorch))
+                    .or_else(|_| {
+                        api.get("model.safetensors")
+                            .map(|filename| (filename, WeightSource::Safetensors))
+                    })
+                    .map_err(NewEmbedderError::api_get)?
+            };
+            (config, tokenizer, weights, source)
+        };
+
+        let config = std::fs::read_to_string(&config_filename)
+            .map_err(|inner| NewEmbedderError::open_config(config_filename.clone(), inner))?;
+        let config: Config = serde_json::from_str(&config).map_err(|inner| {
+            NewEmbedderError::deserialize_config(config, config_filename, inner)
+        })?;
+        let mut tokenizer = Tokenizer::from_file(&tokenizer_filename)
+            .map_err(|inner| NewEmbedderError::open_tokenizer(tokenizer_filename, inner))?;
+
+        let vb = match weight_source {
+            WeightSource::Pytorch => VarBuilder::from_pth(&weights_filename, DTYPE, &device)
+                .map_err(NewEmbedderError::pytorch_weight)?,
+            WeightSource::Safetensors => unsafe {
+                VarBuilder::from_mmaped_safetensors(&[weights_filename], DTYPE, &device)
+                    .map_err(NewEmbedderError::safetensor_weight)?
+            },
+        };
+
+        let model = BertModel::load(vb, &config).map_err(NewEmbedderError::load_model)?;
+
+        if let Some(pp) = tokenizer.get_padding_mut() {
+            pp.strategy = tokenizers::PaddingStrategy::BatchLongest
+        } else {
+            let pp = PaddingParams {
+                strategy: tokenizers::PaddingStrategy::BatchLongest,
+                ..Default::default()
+            };
+            tokenizer.with_padding(Some(pp));
+        }
+
+        let mut this = Self { model, tokenizer, options, dimensions: 0 };
+
+        let embeddings = this
+            .embed(vec!["test".into()])
+            .map_err(NewEmbedderError::hf_could_not_determine_dimension)?;
+        this.dimensions = embeddings.first().unwrap().dimension();
+
+        Ok(this)
+    }
+
+    pub fn embed(
+        &self,
+        mut texts: Vec<String>,
+    ) -> std::result::Result<Vec<Embeddings<f32>>, EmbedError> {
+        let tokens = match texts.len() {
+            1 => vec![self
+                .tokenizer
+                .encode(texts.pop().unwrap(), true)
+                .map_err(EmbedError::tokenize)?],
+            _ => self.tokenizer.encode_batch(texts, true).map_err(EmbedError::tokenize)?,
+        };
+        let token_ids = tokens
+            .iter()
+            .map(|tokens| {
+                let tokens = tokens.get_ids().to_vec();
+                Tensor::new(tokens.as_slice(), &self.model.device).map_err(EmbedError::tensor_shape)
+            })
+            .collect::<Result<Vec<_>, EmbedError>>()?;
+
+        let token_ids = Tensor::stack(&token_ids, 0).map_err(EmbedError::tensor_shape)?;
+        let token_type_ids = token_ids.zeros_like().map_err(EmbedError::tensor_shape)?;
+        let embeddings =
+            self.model.forward(&token_ids, &token_type_ids).map_err(EmbedError::model_forward)?;
+
+        // Apply some avg-pooling by taking the mean embedding value for all tokens (including padding)
+        let (_n_sentence, n_tokens, _hidden_size) =
+            embeddings.dims3().map_err(EmbedError::tensor_shape)?;
+
+        let embeddings = (embeddings.sum(1).map_err(EmbedError::tensor_value)? / (n_tokens as f64))
+            .map_err(EmbedError::tensor_shape)?;
+
+        let embeddings: Vec<Embedding> = embeddings.to_vec2().map_err(EmbedError::tensor_shape)?;
+        Ok(embeddings.into_iter().map(Embeddings::from_single_embedding).collect())
+    }
+
+    pub fn embed_chunks(
+        &self,
+        text_chunks: Vec<Vec<String>>,
+    ) -> std::result::Result<Vec<Vec<Embeddings<f32>>>, EmbedError> {
+        text_chunks.into_iter().map(|prompts| self.embed(prompts)).collect()
+    }
+
+    pub fn chunk_count_hint(&self) -> usize {
+        1
+    }
+
+    pub fn prompt_count_in_chunk_hint(&self) -> usize {
+        std::thread::available_parallelism().map(|x| x.get()).unwrap_or(8)
+    }
+
+    pub fn dimensions(&self) -> usize {
+        self.dimensions
+    }
+
+    pub fn distribution(&self) -> Option<DistributionShift> {
+        if self.options.model == "BAAI/bge-base-en-v1.5" {
+            Some(DistributionShift { current_mean: 0.85, current_sigma: 0.1 })
+        } else {
+            None
+        }
+    }
+}

milli/src/vector/manual.rs

@@ -0,0 +1,34 @@
+use super::error::EmbedError;
+use super::Embeddings;
+
+#[derive(Debug, Clone, Copy)]
+pub struct Embedder {
+    dimensions: usize,
+}
+
+#[derive(Debug, Clone, Hash, PartialEq, Eq, serde::Deserialize, serde::Serialize)]
+pub struct EmbedderOptions {
+    pub dimensions: usize,
+}
+
+impl Embedder {
+    pub fn new(options: EmbedderOptions) -> Self {
+        Self { dimensions: options.dimensions }
+    }
+
+    pub fn embed(&self, mut texts: Vec<String>) -> Result<Vec<Embeddings<f32>>, EmbedError> {
+        let Some(text) = texts.pop() else { return Ok(Default::default()) };
+        Err(EmbedError::embed_on_manual_embedder(text))
+    }
+
+    pub fn dimensions(&self) -> usize {
+        self.dimensions
+    }
+
+    pub fn embed_chunks(
+        &self,
+        text_chunks: Vec<Vec<String>>,
+    ) -> Result<Vec<Vec<Embeddings<f32>>>, EmbedError> {
+        text_chunks.into_iter().map(|prompts| self.embed(prompts)).collect()
+    }
+}

milli/src/vector/mod.rs

@@ -0,0 +1,257 @@
+use std::collections::HashMap;
+use std::sync::Arc;
+
+use self::error::{EmbedError, NewEmbedderError};
+use crate::prompt::{Prompt, PromptData};
+
+pub mod error;
+pub mod hf;
+pub mod manual;
+pub mod openai;
+pub mod settings;
+
+pub use self::error::Error;
+
+pub type Embedding = Vec<f32>;
+
+pub struct Embeddings<F> {
+    data: Vec<F>,
+    dimension: usize,
+}
+
+impl<F> Embeddings<F> {
+    pub fn new(dimension: usize) -> Self {
+        Self { data: Default::default(), dimension }
+    }
+
+    pub fn from_single_embedding(embedding: Vec<F>) -> Self {
+        Self { dimension: embedding.len(), data: embedding }
+    }
+
+    pub fn from_inner(data: Vec<F>, dimension: usize) -> Result<Self, Vec<F>> {
+        let mut this = Self::new(dimension);
+        this.append(data)?;
+        Ok(this)
+    }
+
+    pub fn embedding_count(&self) -> usize {
+        self.data.len() / self.dimension
+    }
+
+    pub fn dimension(&self) -> usize {
+        self.dimension
+    }
+
+    pub fn into_inner(self) -> Vec<F> {
+        self.data
+    }
+
+    pub fn as_inner(&self) -> &[F] {
+        &self.data
+    }
+
+    pub fn iter(&self) -> impl Iterator<Item = &'_ [F]> + '_ {
+        self.data.as_slice().chunks_exact(self.dimension)
+    }
+
+    pub fn push(&mut self, mut embedding: Vec<F>) -> Result<(), Vec<F>> {
+        if embedding.len() != self.dimension {
+            return Err(embedding);
+        }
+        self.data.append(&mut embedding);
+        Ok(())
+    }
+
+    pub fn append(&mut self, mut embeddings: Vec<F>) -> Result<(), Vec<F>> {
+        if embeddings.len() % self.dimension != 0 {
+            return Err(embeddings);
+        }
+        self.data.append(&mut embeddings);
+        Ok(())
+    }
+}
+
+#[derive(Debug)]
+pub enum Embedder {
+    HuggingFace(hf::Embedder),
+    OpenAi(openai::Embedder),
+    UserProvided(manual::Embedder),
+}
+
+#[derive(Debug, Clone, Default, serde::Deserialize, serde::Serialize)]
+pub struct EmbeddingConfig {
+    pub embedder_options: EmbedderOptions,
+    pub prompt: PromptData,
+    // TODO: add metrics and anything needed
+}
+
+#[derive(Clone, Default)]
+pub struct EmbeddingConfigs(HashMap<String, (Arc<Embedder>, Arc<Prompt>)>);
+
+impl EmbeddingConfigs {
+    pub fn new(data: HashMap<String, (Arc<Embedder>, Arc<Prompt>)>) -> Self {
+        Self(data)
+    }
+
+    pub fn get(&self, name: &str) -> Option<(Arc<Embedder>, Arc<Prompt>)> {
+        self.0.get(name).cloned()
+    }
+
+    pub fn get_default(&self) -> Option<(Arc<Embedder>, Arc<Prompt>)> {
+        self.get_default_embedder_name().and_then(|default| self.get(&default))
+    }
+
+    pub fn get_default_embedder_name(&self) -> Option<String> {
+        let mut it = self.0.keys();
+        let first_name = it.next();
+        let second_name = it.next();
+        match (first_name, second_name) {
+            (None, _) => None,
+            (Some(first), None) => Some(first.to_owned()),
+            (Some(_), Some(_)) => Some("default".to_owned()),
+        }
+    }
+}
+
+impl IntoIterator for EmbeddingConfigs {
+    type Item = (String, (Arc<Embedder>, Arc<Prompt>));
+
+    type IntoIter = std::collections::hash_map::IntoIter<String, (Arc<Embedder>, Arc<Prompt>)>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        self.0.into_iter()
+    }
+}
+
+#[derive(Debug, Clone, Hash, PartialEq, Eq, serde::Deserialize, serde::Serialize)]
+pub enum EmbedderOptions {
+    HuggingFace(hf::EmbedderOptions),
+    OpenAi(openai::EmbedderOptions),
+    UserProvided(manual::EmbedderOptions),
+}
+
+impl Default for EmbedderOptions {
+    fn default() -> Self {
+        Self::HuggingFace(Default::default())
+    }
+}
+
+impl EmbedderOptions {
+    pub fn huggingface() -> Self {
+        Self::HuggingFace(hf::EmbedderOptions::new())
+    }
+
+    pub fn openai(api_key: Option<String>) -> Self {
+        Self::OpenAi(openai::EmbedderOptions::with_default_model(api_key))
+    }
+}
+
+impl Embedder {
+    pub fn new(options: EmbedderOptions) -> std::result::Result<Self, NewEmbedderError> {
+        Ok(match options {
+            EmbedderOptions::HuggingFace(options) => Self::HuggingFace(hf::Embedder::new(options)?),
+            EmbedderOptions::OpenAi(options) => Self::OpenAi(openai::Embedder::new(options)?),
+            EmbedderOptions::UserProvided(options) => {
+                Self::UserProvided(manual::Embedder::new(options))
+            }
+        })
+    }
+
+    pub async fn embed(
+        &self,
+        texts: Vec<String>,
+    ) -> std::result::Result<Vec<Embeddings<f32>>, EmbedError> {
+        match self {
+            Embedder::HuggingFace(embedder) => embedder.embed(texts),
+            Embedder::OpenAi(embedder) => embedder.embed(texts).await,
+            Embedder::UserProvided(embedder) => embedder.embed(texts),
+        }
+    }
+
+    pub async fn embed_chunks(
+        &self,
+        text_chunks: Vec<Vec<String>>,
+    ) -> std::result::Result<Vec<Vec<Embeddings<f32>>>, EmbedError> {
+        match self {
+            Embedder::HuggingFace(embedder) => embedder.embed_chunks(text_chunks),
+            Embedder::OpenAi(embedder) => embedder.embed_chunks(text_chunks).await,
+            Embedder::UserProvided(embedder) => embedder.embed_chunks(text_chunks),
+        }
+    }
+
+    pub fn chunk_count_hint(&self) -> usize {
+        match self {
+            Embedder::HuggingFace(embedder) => embedder.chunk_count_hint(),
+            Embedder::OpenAi(embedder) => embedder.chunk_count_hint(),
+            Embedder::UserProvided(_) => 1,
+        }
+    }
+
+    pub fn prompt_count_in_chunk_hint(&self) -> usize {
+        match self {
+            Embedder::HuggingFace(embedder) => embedder.prompt_count_in_chunk_hint(),
+            Embedder::OpenAi(embedder) => embedder.prompt_count_in_chunk_hint(),
+            Embedder::UserProvided(_) => 1,
+        }
+    }
+
+    pub fn dimensions(&self) -> usize {
+        match self {
+            Embedder::HuggingFace(embedder) => embedder.dimensions(),
+            Embedder::OpenAi(embedder) => embedder.dimensions(),
+            Embedder::UserProvided(embedder) => embedder.dimensions(),
+        }
+    }
+
+    pub fn distribution(&self) -> Option<DistributionShift> {
+        match self {
+            Embedder::HuggingFace(embedder) => embedder.distribution(),
+            Embedder::OpenAi(embedder) => embedder.distribution(),
+            Embedder::UserProvided(_embedder) => None,
+        }
+    }
+}
+
+#[derive(Debug, Clone, Copy)]
+pub struct DistributionShift {
+    pub current_mean: f32,
+    pub current_sigma: f32,
+}
+
+impl DistributionShift {
+    /// `None` if sigma <= 0.
+    pub fn new(mean: f32, sigma: f32) -> Option<Self> {
+        if sigma <= 0.0 {
+            None
+        } else {
+            Some(Self { current_mean: mean, current_sigma: sigma })
+        }
+    }
+
+    pub fn shift(&self, score: f32) -> f32 {
+        // <https://math.stackexchange.com/a/2894689>
+        // We're somewhat abusively mapping the distribution of distances to a gaussian.
+        // The parameters we're given is the mean and sigma of the native result distribution.
+        // We're using them to retarget the distribution to a gaussian centered on 0.5 with a sigma of 0.4.
+
+        let target_mean = 0.5;
+        let target_sigma = 0.4;
+
+        // a^2 sig1^2 = sig2^2 => a^2 = sig2^2 / sig1^2 => a = sig2 / sig1, assuming a, sig1, and sig2 positive.
+        let factor = target_sigma / self.current_sigma;
+        // a*mu1 + b = mu2 => b = mu2 - a*mu1
+        let offset = target_mean - (factor * self.current_mean);
+
+        let mut score = factor * score + offset;
+
+        // clamp the final score in the ]0, 1] interval.
+        if score <= 0.0 {
+            score = f32::EPSILON;
+        }
+        if score > 1.0 {
+            score = 1.0;
+        }
+
+        score
+    }
+}

milli/src/vector/openai.rs

@@ -0,0 +1,445 @@
+use std::fmt::Display;
+
+use reqwest::StatusCode;
+use serde::{Deserialize, Serialize};
+
+use super::error::{EmbedError, NewEmbedderError};
+use super::{DistributionShift, Embedding, Embeddings};
+
+#[derive(Debug)]
+pub struct Embedder {
+    client: reqwest::Client,
+    tokenizer: tiktoken_rs::CoreBPE,
+    options: EmbedderOptions,
+}
+
+#[derive(Debug, Clone, Hash, PartialEq, Eq, serde::Deserialize, serde::Serialize)]
+pub struct EmbedderOptions {
+    pub api_key: Option<String>,
+    pub embedding_model: EmbeddingModel,
+}
+
+#[derive(
+    Debug,
+    Clone,
+    Copy,
+    Default,
+    Hash,
+    PartialEq,
+    Eq,
+    serde::Serialize,
+    serde::Deserialize,
+    deserr::Deserr,
+)]
+#[serde(deny_unknown_fields, rename_all = "camelCase")]
+#[deserr(rename_all = camelCase, deny_unknown_fields)]
+pub enum EmbeddingModel {
+    #[default]
+    #[serde(rename = "text-embedding-ada-002")]
+    #[deserr(rename = "text-embedding-ada-002")]
+    TextEmbeddingAda002,
+}
+
+impl EmbeddingModel {
+    pub fn max_token(&self) -> usize {
+        match self {
+            EmbeddingModel::TextEmbeddingAda002 => 8191,
+        }
+    }
+
+    pub fn dimensions(&self) -> usize {
+        match self {
+            EmbeddingModel::TextEmbeddingAda002 => 1536,
+        }
+    }
+
+    pub fn name(&self) -> &'static str {
+        match self {
+            EmbeddingModel::TextEmbeddingAda002 => "text-embedding-ada-002",
+        }
+    }
+
+    pub fn from_name(name: &'static str) -> Option<Self> {
+        match name {
+            "text-embedding-ada-002" => Some(EmbeddingModel::TextEmbeddingAda002),
+            _ => None,
+        }
+    }
+
+    fn distribution(&self) -> Option<DistributionShift> {
+        match self {
+            EmbeddingModel::TextEmbeddingAda002 => {
+                Some(DistributionShift { current_mean: 0.90, current_sigma: 0.08 })
+            }
+        }
+    }
+}
+
+pub const OPENAI_EMBEDDINGS_URL: &str = "https://api.openai.com/v1/embeddings";
+
+impl EmbedderOptions {
+    pub fn with_default_model(api_key: Option<String>) -> Self {
+        Self { api_key, embedding_model: Default::default() }
+    }
+
+    pub fn with_embedding_model(api_key: Option<String>, embedding_model: EmbeddingModel) -> Self {
+        Self { api_key, embedding_model }
+    }
+}
+
+impl Embedder {
+    pub fn new(options: EmbedderOptions) -> Result<Self, NewEmbedderError> {
+        let mut headers = reqwest::header::HeaderMap::new();
+        let mut inferred_api_key = Default::default();
+        let api_key = options.api_key.as_ref().unwrap_or_else(|| {
+            inferred_api_key = infer_api_key();
+            &inferred_api_key
+        });
+        headers.insert(
+            reqwest::header::AUTHORIZATION,
+            reqwest::header::HeaderValue::from_str(&format!("Bearer {}", api_key))
+                .map_err(NewEmbedderError::openai_invalid_api_key_format)?,
+        );
+        headers.insert(
+            reqwest::header::CONTENT_TYPE,
+            reqwest::header::HeaderValue::from_static("application/json"),
+        );
+        let client = reqwest::ClientBuilder::new()
+            .default_headers(headers)
+            .build()
+            .map_err(NewEmbedderError::openai_initialize_web_client)?;
+
+        // looking at the code it is very unclear that this can actually fail.
+        let tokenizer = tiktoken_rs::cl100k_base().unwrap();
+
+        Ok(Self { options, client, tokenizer })
+    }
+
+    pub async fn embed(&self, texts: Vec<String>) -> Result<Vec<Embeddings<f32>>, EmbedError> {
+        let mut tokenized = false;
+
+        for attempt in 0..7 {
+            let result = if tokenized {
+                self.try_embed_tokenized(&texts).await
+            } else {
+                self.try_embed(&texts).await
+            };
+
+            let retry_duration = match result {
+                Ok(embeddings) => return Ok(embeddings),
+                Err(retry) => {
+                    log::warn!("Failed: {}", retry.error);
+                    tokenized |= retry.must_tokenize();
+                    retry.into_duration(attempt)
+                }
+            }?;
+            log::warn!("Attempt #{}, retrying after {}ms.", attempt, retry_duration.as_millis());
+            tokio::time::sleep(retry_duration).await;
+        }
+
+        let result = if tokenized {
+            self.try_embed_tokenized(&texts).await
+        } else {
+            self.try_embed(&texts).await
+        };
+
+        result.map_err(Retry::into_error)
+    }
+
+    async fn check_response(response: reqwest::Response) -> Result<reqwest::Response, Retry> {
+        if !response.status().is_success() {
+            match response.status() {
+                StatusCode::UNAUTHORIZED => {
+                    let error_response: OpenAiErrorResponse = response
+                        .json()
+                        .await
+                        .map_err(EmbedError::openai_unexpected)
+                        .map_err(Retry::retry_later)?;
+
+                    return Err(Retry::give_up(EmbedError::openai_auth_error(
+                        error_response.error,
+                    )));
+                }
+                StatusCode::TOO_MANY_REQUESTS => {
+                    let error_response: OpenAiErrorResponse = response
+                        .json()
+                        .await
+                        .map_err(EmbedError::openai_unexpected)
+                        .map_err(Retry::retry_later)?;
+
+                    return Err(Retry::rate_limited(EmbedError::openai_too_many_requests(
+                        error_response.error,
+                    )));
+                }
+                StatusCode::INTERNAL_SERVER_ERROR => {
+                    let error_response: OpenAiErrorResponse = response
+                        .json()
+                        .await
+                        .map_err(EmbedError::openai_unexpected)
+                        .map_err(Retry::retry_later)?;
+                    return Err(Retry::retry_later(EmbedError::openai_internal_server_error(
+                        error_response.error,
+                    )));
+                }
+                StatusCode::SERVICE_UNAVAILABLE => {
+                    let error_response: OpenAiErrorResponse = response
+                        .json()
+                        .await
+                        .map_err(EmbedError::openai_unexpected)
+                        .map_err(Retry::retry_later)?;
+                    return Err(Retry::retry_later(EmbedError::openai_internal_server_error(
+                        error_response.error,
+                    )));
+                }
+                StatusCode::BAD_REQUEST => {
+                    // Most probably, one text contained too many tokens
+                    let error_response: OpenAiErrorResponse = response
+                        .json()
+                        .await
+                        .map_err(EmbedError::openai_unexpected)
+                        .map_err(Retry::retry_later)?;
+
+                    log::warn!("OpenAI: input was too long, retrying on tokenized version. For best performance, limit the size of your prompt.");
+
+                    return Err(Retry::retry_tokenized(EmbedError::openai_too_many_tokens(
+                        error_response.error,
+                    )));
+                }
+                code => {
+                    return Err(Retry::give_up(EmbedError::openai_unhandled_status_code(
+                        code.as_u16(),
+                    )));
+                }
+            }
+        }
+        Ok(response)
+    }
+
+    async fn try_embed<S: AsRef<str> + serde::Serialize>(
+        &self,
+        texts: &[S],
+    ) -> Result<Vec<Embeddings<f32>>, Retry> {
+        for text in texts {
+            log::trace!("Received prompt: {}", text.as_ref())
+        }
+        let request = OpenAiRequest { model: self.options.embedding_model.name(), input: texts };
+        let response = self
+            .client
+            .post(OPENAI_EMBEDDINGS_URL)
+            .json(&request)
+            .send()
+            .await
+            .map_err(EmbedError::openai_network)
+            .map_err(Retry::retry_later)?;
+
+        let response = Self::check_response(response).await?;
+
+        let response: OpenAiResponse = response
+            .json()
+            .await
+            .map_err(EmbedError::openai_unexpected)
+            .map_err(Retry::retry_later)?;
+
+        log::trace!("response: {:?}", response.data);
+
+        Ok(response
+            .data
+            .into_iter()
+            .map(|data| Embeddings::from_single_embedding(data.embedding))
+            .collect())
+    }
+
+    async fn try_embed_tokenized(&self, text: &[String]) -> Result<Vec<Embeddings<f32>>, Retry> {
+        pub const OVERLAP_SIZE: usize = 200;
+        let mut all_embeddings = Vec::with_capacity(text.len());
+        for text in text {
+            let max_token_count = self.options.embedding_model.max_token();
+            let encoded = self.tokenizer.encode_ordinary(text.as_str());
+            let len = encoded.len();
+            if len < max_token_count {
+                all_embeddings.append(&mut self.try_embed(&[text]).await?);
+                continue;
+            }
+
+            let mut tokens = encoded.as_slice();
+            let mut embeddings_for_prompt =
+                Embeddings::new(self.options.embedding_model.dimensions());
+            while tokens.len() > max_token_count {
+                let window = &tokens[..max_token_count];
+                embeddings_for_prompt.push(self.embed_tokens(window).await?).unwrap();
+
+                tokens = &tokens[max_token_count - OVERLAP_SIZE..];
+            }
+
+            // end of text
+            embeddings_for_prompt.push(self.embed_tokens(tokens).await?).unwrap();
+
+            all_embeddings.push(embeddings_for_prompt);
+        }
+        Ok(all_embeddings)
+    }
+
+    async fn embed_tokens(&self, tokens: &[usize]) -> Result<Embedding, Retry> {
+        for attempt in 0..9 {
+            let duration = match self.try_embed_tokens(tokens).await {
+                Ok(embedding) => return Ok(embedding),
+                Err(retry) => retry.into_duration(attempt),
+            }
+            .map_err(Retry::retry_later)?;
+
+            tokio::time::sleep(duration).await;
+        }
+
+        self.try_embed_tokens(tokens).await.map_err(|retry| Retry::give_up(retry.into_error()))
+    }
+
+    async fn try_embed_tokens(&self, tokens: &[usize]) -> Result<Embedding, Retry> {
+        let request =
+            OpenAiTokensRequest { model: self.options.embedding_model.name(), input: tokens };
+        let response = self
+            .client
+            .post(OPENAI_EMBEDDINGS_URL)
+            .json(&request)
+            .send()
+            .await
+            .map_err(EmbedError::openai_network)
+            .map_err(Retry::retry_later)?;
+
+        let response = Self::check_response(response).await?;
+
+        let mut response: OpenAiResponse = response
+            .json()
+            .await
+            .map_err(EmbedError::openai_unexpected)
+            .map_err(Retry::retry_later)?;
+        Ok(response.data.pop().map(|data| data.embedding).unwrap_or_default())
+    }
+
+    pub async fn embed_chunks(
+        &self,
+        text_chunks: Vec<Vec<String>>,
+    ) -> Result<Vec<Vec<Embeddings<f32>>>, EmbedError> {
+        futures::future::try_join_all(text_chunks.into_iter().map(|prompts| self.embed(prompts)))
+            .await
+    }
+
+    pub fn chunk_count_hint(&self) -> usize {
+        10
+    }
+
+    pub fn prompt_count_in_chunk_hint(&self) -> usize {
+        10
+    }
+
+    pub fn dimensions(&self) -> usize {
+        self.options.embedding_model.dimensions()
+    }
+
+    pub fn distribution(&self) -> Option<DistributionShift> {
+        self.options.embedding_model.distribution()
+    }
+}
+
+// retrying in case of failure
+
+struct Retry {
+    error: EmbedError,
+    strategy: RetryStrategy,
+}
+
+enum RetryStrategy {
+    GiveUp,
+    Retry,
+    RetryTokenized,
+    RetryAfterRateLimit,
+}
+
+impl Retry {
+    fn give_up(error: EmbedError) -> Self {
+        Self { error, strategy: RetryStrategy::GiveUp }
+    }
+
+    fn retry_later(error: EmbedError) -> Self {
+        Self { error, strategy: RetryStrategy::Retry }
+    }
+
+    fn retry_tokenized(error: EmbedError) -> Self {
+        Self { error, strategy: RetryStrategy::RetryTokenized }
+    }
+
+    fn rate_limited(error: EmbedError) -> Self {
+        Self { error, strategy: RetryStrategy::RetryAfterRateLimit }
+    }
+
+    fn into_duration(self, attempt: u32) -> Result<tokio::time::Duration, EmbedError> {
+        match self.strategy {
+            RetryStrategy::GiveUp => Err(self.error),
+            RetryStrategy::Retry => Ok(tokio::time::Duration::from_millis((10u64).pow(attempt))),
+            RetryStrategy::RetryTokenized => Ok(tokio::time::Duration::from_millis(1)),
+            RetryStrategy::RetryAfterRateLimit => {
+                Ok(tokio::time::Duration::from_millis(100 + 10u64.pow(attempt)))
+            }
+        }
+    }
+
+    fn must_tokenize(&self) -> bool {
+        matches!(self.strategy, RetryStrategy::RetryTokenized)
+    }
+
+    fn into_error(self) -> EmbedError {
+        self.error
+    }
+}
+
+// openai api structs
+
+#[derive(Debug, Serialize)]
+struct OpenAiRequest<'a, S: AsRef<str> + serde::Serialize> {
+    model: &'a str,
+    input: &'a [S],
+}
+
+#[derive(Debug, Serialize)]
+struct OpenAiTokensRequest<'a> {
+    model: &'a str,
+    input: &'a [usize],
+}
+
+#[derive(Debug, Deserialize)]
+struct OpenAiResponse {
+    data: Vec<OpenAiEmbedding>,
+}
+
+#[derive(Debug, Deserialize)]
+struct OpenAiErrorResponse {
+    error: OpenAiError,
+}
+
+#[derive(Debug, Deserialize)]
+pub struct OpenAiError {
+    message: String,
+    // type: String,
+    code: Option<String>,
+}
+
+impl Display for OpenAiError {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match &self.code {
+            Some(code) => write!(f, "{} ({})", self.message, code),
+            None => write!(f, "{}", self.message),
+        }
+    }
+}
+
+#[derive(Debug, Deserialize)]
+struct OpenAiEmbedding {
+    embedding: Embedding,
+    // object: String,
+    // index: usize,
+}
+
+fn infer_api_key() -> String {
+    std::env::var("MEILI_OPENAI_API_KEY")
+        .or_else(|_| std::env::var("OPENAI_API_KEY"))
+        .unwrap_or_default()
+}

milli/src/vector/settings.rs

@@ -0,0 +1,292 @@
+use deserr::Deserr;
+use serde::{Deserialize, Serialize};
+
+use crate::prompt::PromptData;
+use crate::update::Setting;
+use crate::vector::EmbeddingConfig;
+
+#[derive(Debug, Clone, Default, Serialize, Deserialize, PartialEq, Eq, Deserr)]
+#[serde(deny_unknown_fields, rename_all = "camelCase")]
+#[deserr(rename_all = camelCase, deny_unknown_fields)]
+pub struct EmbeddingSettings {
+    #[serde(default, skip_serializing_if = "Setting::is_not_set", rename = "source")]
+    #[deserr(default, rename = "source")]
+    pub embedder_options: Setting<EmbedderSettings>,
+    #[serde(default, skip_serializing_if = "Setting::is_not_set")]
+    #[deserr(default)]
+    pub document_template: Setting<PromptSettings>,
+}
+
+impl EmbeddingSettings {
+    pub fn apply(&mut self, new: Self) {
+        let EmbeddingSettings { embedder_options, document_template: prompt } = new;
+        self.embedder_options.apply(embedder_options);
+        self.document_template.apply(prompt);
+    }
+}
+
+impl From<EmbeddingConfig> for EmbeddingSettings {
+    fn from(value: EmbeddingConfig) -> Self {
+        Self {
+            embedder_options: Setting::Set(value.embedder_options.into()),
+            document_template: Setting::Set(value.prompt.into()),
+        }
+    }
+}
+
+impl From<EmbeddingSettings> for EmbeddingConfig {
+    fn from(value: EmbeddingSettings) -> Self {
+        let mut this = Self::default();
+        let EmbeddingSettings { embedder_options, document_template: prompt } = value;
+        if let Some(embedder_options) = embedder_options.set() {
+            this.embedder_options = embedder_options.into();
+        }
+        if let Some(prompt) = prompt.set() {
+            this.prompt = prompt.into();
+        }
+        this
+    }
+}
+
+#[derive(Debug, Clone, Default, Serialize, Deserialize, PartialEq, Eq, Deserr)]
+#[serde(deny_unknown_fields, rename_all = "camelCase")]
+#[deserr(rename_all = camelCase, deny_unknown_fields)]
+pub struct PromptSettings {
+    #[serde(default, skip_serializing_if = "Setting::is_not_set")]
+    #[deserr(default)]
+    pub template: Setting<String>,
+}
+
+impl PromptSettings {
+    pub fn apply(&mut self, new: Self) {
+        let PromptSettings { template } = new;
+        self.template.apply(template);
+    }
+}
+
+impl From<PromptData> for PromptSettings {
+    fn from(value: PromptData) -> Self {
+        Self { template: Setting::Set(value.template) }
+    }
+}
+
+impl From<PromptSettings> for PromptData {
+    fn from(value: PromptSettings) -> Self {
+        let mut this = PromptData::default();
+        let PromptSettings { template } = value;
+        if let Some(template) = template.set() {
+            this.template = template;
+        }
+        this
+    }
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]
+#[serde(deny_unknown_fields, rename_all = "camelCase")]
+pub enum EmbedderSettings {
+    HuggingFace(Setting<HfEmbedderSettings>),
+    OpenAi(Setting<OpenAiEmbedderSettings>),
+    UserProvided(UserProvidedSettings),
+}
+
+impl<E> Deserr<E> for EmbedderSettings
+where
+    E: deserr::DeserializeError,
+{
+    fn deserialize_from_value<V: deserr::IntoValue>(
+        value: deserr::Value<V>,
+        location: deserr::ValuePointerRef,
+    ) -> Result<Self, E> {
+        match value {
+            deserr::Value::Map(map) => {
+                if deserr::Map::len(&map) != 1 {
+                    return Err(deserr::take_cf_content(E::error::<V>(
+                        None,
+                        deserr::ErrorKind::Unexpected {
+                            msg: format!(
+                                "Expected a single field, got {} fields",
+                                deserr::Map::len(&map)
+                            ),
+                        },
+                        location,
+                    )));
+                }
+                let mut it = deserr::Map::into_iter(map);
+                let (k, v) = it.next().unwrap();
+
+                match k.as_str() {
+                    "huggingFace" => Ok(EmbedderSettings::HuggingFace(Setting::Set(
+                        HfEmbedderSettings::deserialize_from_value(
+                            v.into_value(),
+                            location.push_key(&k),
+                        )?,
+                    ))),
+                    "openAi" => Ok(EmbedderSettings::OpenAi(Setting::Set(
+                        OpenAiEmbedderSettings::deserialize_from_value(
+                            v.into_value(),
+                            location.push_key(&k),
+                        )?,
+                    ))),
+                    "userProvided" => Ok(EmbedderSettings::UserProvided(
+                        UserProvidedSettings::deserialize_from_value(
+                            v.into_value(),
+                            location.push_key(&k),
+                        )?,
+                    )),
+                    other => Err(deserr::take_cf_content(E::error::<V>(
+                        None,
+                        deserr::ErrorKind::UnknownKey {
+                            key: other,
+                            accepted: &["huggingFace", "openAi", "userProvided"],
+                        },
+                        location,
+                    ))),
+                }
+            }
+            _ => Err(deserr::take_cf_content(E::error::<V>(
+                None,
+                deserr::ErrorKind::IncorrectValueKind {
+                    actual: value,
+                    accepted: &[deserr::ValueKind::Map],
+                },
+                location,
+            ))),
+        }
+    }
+}
+
+impl Default for EmbedderSettings {
+    fn default() -> Self {
+        Self::OpenAi(Default::default())
+    }
+}
+
+impl From<crate::vector::EmbedderOptions> for EmbedderSettings {
+    fn from(value: crate::vector::EmbedderOptions) -> Self {
+        match value {
+            crate::vector::EmbedderOptions::HuggingFace(hf) => {
+                Self::HuggingFace(Setting::Set(hf.into()))
+            }
+            crate::vector::EmbedderOptions::OpenAi(openai) => {
+                Self::OpenAi(Setting::Set(openai.into()))
+            }
+            crate::vector::EmbedderOptions::UserProvided(user_provided) => {
+                Self::UserProvided(user_provided.into())
+            }
+        }
+    }
+}
+
+impl From<EmbedderSettings> for crate::vector::EmbedderOptions {
+    fn from(value: EmbedderSettings) -> Self {
+        match value {
+            EmbedderSettings::HuggingFace(Setting::Set(hf)) => Self::HuggingFace(hf.into()),
+            EmbedderSettings::HuggingFace(_setting) => Self::HuggingFace(Default::default()),
+            EmbedderSettings::OpenAi(Setting::Set(ai)) => Self::OpenAi(ai.into()),
+            EmbedderSettings::OpenAi(_setting) => {
+                Self::OpenAi(crate::vector::openai::EmbedderOptions::with_default_model(None))
+            }
+            EmbedderSettings::UserProvided(user_provided) => {
+                Self::UserProvided(user_provided.into())
+            }
+        }
+    }
+}
+
+#[derive(Debug, Clone, Default, Serialize, Deserialize, PartialEq, Eq, Deserr)]
+#[serde(deny_unknown_fields, rename_all = "camelCase")]
+#[deserr(rename_all = camelCase, deny_unknown_fields)]
+pub struct HfEmbedderSettings {
+    #[serde(default, skip_serializing_if = "Setting::is_not_set")]
+    #[deserr(default)]
+    pub model: Setting<String>,
+    #[serde(default, skip_serializing_if = "Setting::is_not_set")]
+    #[deserr(default)]
+    pub revision: Setting<String>,
+}
+
+impl HfEmbedderSettings {
+    pub fn apply(&mut self, new: Self) {
+        let HfEmbedderSettings { model, revision } = new;
+        self.model.apply(model);
+        self.revision.apply(revision);
+    }
+}
+
+impl From<crate::vector::hf::EmbedderOptions> for HfEmbedderSettings {
+    fn from(value: crate::vector::hf::EmbedderOptions) -> Self {
+        Self {
+            model: Setting::Set(value.model),
+            revision: value.revision.map(Setting::Set).unwrap_or(Setting::NotSet),
+        }
+    }
+}
+
+impl From<HfEmbedderSettings> for crate::vector::hf::EmbedderOptions {
+    fn from(value: HfEmbedderSettings) -> Self {
+        let HfEmbedderSettings { model, revision } = value;
+        let mut this = Self::default();
+        if let Some(model) = model.set() {
+            this.model = model;
+        }
+        if let Some(revision) = revision.set() {
+            this.revision = Some(revision);
+        }
+        this
+    }
+}
+
+#[derive(Debug, Clone, Default, Serialize, Deserialize, PartialEq, Eq, Deserr)]
+#[serde(deny_unknown_fields, rename_all = "camelCase")]
+#[deserr(rename_all = camelCase, deny_unknown_fields)]
+pub struct OpenAiEmbedderSettings {
+    #[serde(default, skip_serializing_if = "Setting::is_not_set")]
+    #[deserr(default)]
+    pub api_key: Setting<String>,
+    #[serde(default, skip_serializing_if = "Setting::is_not_set", rename = "model")]
+    #[deserr(default, rename = "model")]
+    pub embedding_model: Setting<crate::vector::openai::EmbeddingModel>,
+}
+
+impl OpenAiEmbedderSettings {
+    pub fn apply(&mut self, new: Self) {
+        let Self { api_key, embedding_model: embedding_mode } = new;
+        self.api_key.apply(api_key);
+        self.embedding_model.apply(embedding_mode);
+    }
+}
+
+impl From<crate::vector::openai::EmbedderOptions> for OpenAiEmbedderSettings {
+    fn from(value: crate::vector::openai::EmbedderOptions) -> Self {
+        Self {
+            api_key: value.api_key.map(Setting::Set).unwrap_or(Setting::Reset),
+            embedding_model: Setting::Set(value.embedding_model),
+        }
+    }
+}
+
+impl From<OpenAiEmbedderSettings> for crate::vector::openai::EmbedderOptions {
+    fn from(value: OpenAiEmbedderSettings) -> Self {
+        let OpenAiEmbedderSettings { api_key, embedding_model } = value;
+        Self { api_key: api_key.set(), embedding_model: embedding_model.set().unwrap_or_default() }
+    }
+}
+
+#[derive(Debug, Clone, Default, Serialize, Deserialize, PartialEq, Eq, Deserr)]
+#[serde(deny_unknown_fields, rename_all = "camelCase")]
+#[deserr(rename_all = camelCase, deny_unknown_fields)]
+pub struct UserProvidedSettings {
+    pub dimensions: usize,
+}
+
+impl From<UserProvidedSettings> for crate::vector::manual::EmbedderOptions {
+    fn from(value: UserProvidedSettings) -> Self {
+        Self { dimensions: value.dimensions }
+    }
+}
+
+impl From<crate::vector::manual::EmbedderOptions> for UserProvidedSettings {
+    fn from(value: crate::vector::manual::EmbedderOptions) -> Self {
+        Self { dimensions: value.dimensions }
+    }
+}