Merge pull request #128 from meilisearch/stop-words

Stop words

Cargo.lock

@@ -1206,7 +1206,7 @@ checksum = "7ffc5c5338469d4d3ea17d269fa8ea3512ad247247c30bd2df69e68309ed0a08"
 [[package]]
 name = "meilisearch-tokenizer"
 version = "0.1.1"
-source = "git+https://github.com/meilisearch/Tokenizer.git?tag=v0.1.4#31ba3ff4a15501f12b7d37ac64ddce7c35a9757c"
+source = "git+https://github.com/meilisearch/Tokenizer.git?tag=v0.2.0#833c48b2ee39071f8b4f51abd15122afdb3c8c06"
 dependencies = [
  "character_converter",
  "cow-utils",

http-ui/Cargo.toml

@@ -10,7 +10,7 @@ anyhow = "1.0.38"
 byte-unit = { version = "4.0.9", default-features = false, features = ["std"] }
 grenad = { git = "https://github.com/Kerollmops/grenad.git", rev = "3adcb26" }
 heed = "0.10.6"
-meilisearch-tokenizer = { git = "https://github.com/meilisearch/Tokenizer.git", tag = "v0.1.4" }
+meilisearch-tokenizer = { git = "https://github.com/meilisearch/Tokenizer.git", tag = "v0.2.0" }
 memmap = "0.7.0"
 milli = { path = "../milli" }
 once_cell = "1.5.2"

http-ui/src/main.rs

@@ -1,4 +1,4 @@
-use std::collections::{BTreeMap, HashMap, HashSet};
+use std::collections::{BTreeMap, BTreeSet, HashMap, HashSet};
 use std::fmt::Display;
 use std::fs::{File, create_dir_all};
 use std::net::SocketAddr;
@@ -128,7 +128,10 @@ struct Highlighter<'a, A> {
 
 impl<'a, A: AsRef<[u8]>> Highlighter<'a, A> {
     fn new(stop_words: &'a fst::Set<A>) -> Self {
-        let analyzer = Analyzer::new(AnalyzerConfig::default_with_stopwords(stop_words));
+        let mut config = AnalyzerConfig::default();
+        config.stop_words(stop_words);
+        let analyzer = Analyzer::new(config);
+
         Self { analyzer }
     }
 
@@ -266,6 +269,13 @@ struct Settings {
         skip_serializing_if = "Option::is_none",
     )]
     criteria: Option<Option<Vec<String>>>,
+
+    #[serde(
+        default,
+        deserialize_with = "deserialize_some",
+        skip_serializing_if = "Option::is_none",
+    )]
+    stop_words: Option<Option<BTreeSet<String>>>,
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
@@ -439,6 +449,14 @@ async fn main() -> anyhow::Result<()> {
                         }
                     }
 
+                    // We transpose the settings JSON struct into a real setting update.
+                    if let Some(stop_words) = settings.stop_words {
+                        match stop_words {
+                            Some(stop_words) => builder.set_stop_words(stop_words),
+                            None => builder.reset_stop_words(),
+                        }
+                    }
+
                     let result = builder.execute(|indexing_step, update_id| {
                         let (current, total) = match indexing_step {
                             TransformFromUserIntoGenericFormat { documents_seen } => (documents_seen, None),

milli/Cargo.toml

@@ -20,7 +20,7 @@ heed = { version = "0.10.6", default-features = false, features = ["lmdb", "sync
 human_format = "1.0.3"
 levenshtein_automata = { version = "0.2.0", features = ["fst_automaton"] }
 linked-hash-map = "0.5.4"
-meilisearch-tokenizer = { git = "https://github.com/meilisearch/Tokenizer.git", tag = "v0.1.4" }
+meilisearch-tokenizer = { git = "https://github.com/meilisearch/Tokenizer.git", tag = "v0.2.0" }
 memmap = "0.7.0"
 num-traits = "0.2.14"
 obkv = "0.1.1"

milli/src/index.rs

@@ -28,6 +28,7 @@ pub const SEARCHABLE_FIELDS_KEY: &str = "searchable-fields";
 pub const HARD_EXTERNAL_DOCUMENTS_IDS_KEY: &str = "hard-external-documents-ids";
 pub const SOFT_EXTERNAL_DOCUMENTS_IDS_KEY: &str = "soft-external-documents-ids";
 pub const WORDS_FST_KEY: &str = "words-fst";
+pub const STOP_WORDS_KEY: &str = "stop-words";
 pub const WORDS_PREFIXES_FST_KEY: &str = "words-prefixes-fst";
 const CREATED_AT_KEY: &str = "created-at";
 const UPDATED_AT_KEY: &str = "updated-at";
@@ -377,6 +378,22 @@ impl Index {
         }
     }
 
+    /* stop words */
+
+    pub fn put_stop_words<A: AsRef<[u8]>>(&self, wtxn: &mut RwTxn, fst: &fst::Set<A>) -> heed::Result<()> {
+        self.main.put::<_, Str, ByteSlice>(wtxn, STOP_WORDS_KEY, fst.as_fst().as_bytes())
+    }
+
+    pub fn delete_stop_words(&self, wtxn: &mut RwTxn) -> heed::Result<bool> {
+        self.main.delete::<_, Str>(wtxn, STOP_WORDS_KEY)
+    }
+    pub fn stop_words<'t>(&self, rtxn: &'t RoTxn) -> anyhow::Result<Option<fst::Set<&'t [u8]>>> {
+        match self.main.get::<_, Str, ByteSlice>(rtxn, STOP_WORDS_KEY)? {
+            Some(bytes) => Ok(Some(fst::Set::new(bytes)?)),
+            None => Ok(None),
+        }
+    }
+
     /* words prefixes fst */
 
     /// Writes the FST which is the words prefixes dictionnary of the engine.

milli/src/search/mod.rs

@@ -4,7 +4,7 @@ use std::fmt;
 use std::str::Utf8Error;
 use std::time::Instant;
 
-use fst::{IntoStreamer, Streamer, Set};
+use fst::{IntoStreamer, Streamer};
 use levenshtein_automata::{DFA, LevenshteinAutomatonBuilder as LevBuilder};
 use log::debug;
 use meilisearch_tokenizer::{AnalyzerConfig, Analyzer};
@@ -91,8 +91,7 @@ impl<'a> Search<'a> {
                 let mut builder = QueryTreeBuilder::new(self.rtxn, self.index);
                 builder.optional_words(self.optional_words);
                 builder.authorize_typos(self.authorize_typos);
-                let stop_words = &Set::default();
+                let analyzer = Analyzer::<Vec<u8>>::new(AnalyzerConfig::default());
-                let analyzer = Analyzer::new(AnalyzerConfig::default_with_stopwords(stop_words));
                 let result = analyzer.analyze(query);
                 let tokens = result.tokens();
                 builder.build(tokens)?

milli/src/search/query_tree.rs

@@ -1,6 +1,7 @@
 use std::collections::HashSet;
 use std::{fmt, cmp, mem};
 
+use fst::Set;
 use levenshtein_automata::{DFA, Distance};
 use meilisearch_tokenizer::{TokenKind, tokenizer::TokenStream};
 use roaring::RoaringBitmap;
@@ -154,6 +155,10 @@ impl fmt::Debug for Query {
 
 trait Context {
     fn word_docids(&self, word: &str) -> heed::Result<Option<RoaringBitmap>>;
+    fn stop_words(&self) -> anyhow::Result<Option<Set<&[u8]>>>;
+    fn is_stop_word(&self, word: &str) -> anyhow::Result<bool> {
+        Ok(self.stop_words()?.map_or(false, |s| s.contains(word)))
+    }
     fn synonyms<S: AsRef<str>>(&self, words: &[S]) -> heed::Result<Option<Vec<Vec<String>>>>;
     fn word_documents_count(&self, word: &str) -> heed::Result<Option<u64>> {
         match self.word_docids(word)? {
@@ -183,6 +188,10 @@ impl<'a> Context for QueryTreeBuilder<'a> {
     fn synonyms<S: AsRef<str>>(&self, _words: &[S]) -> heed::Result<Option<Vec<Vec<String>>>> {
         Ok(None)
     }
+
+    fn stop_words(&self) -> anyhow::Result<Option<Set<&[u8]>>> {
+        self.index.stop_words(self.rtxn)
+    }
 }
 
 impl<'a> QueryTreeBuilder<'a> {
@@ -331,8 +340,7 @@ fn create_query_tree(
     optional_words: bool,
     authorize_typos: bool,
     query: PrimitiveQuery,
-) -> anyhow::Result<Operation>
+) -> anyhow::Result<Operation> {
-{
     /// Matches on the `PrimitiveQueryPart` and create an operation from it.
     fn resolve_primitive_part(
         ctx: &impl Context,
@@ -350,7 +358,12 @@ fn create_query_tree(
                 if let Some(child) = split_best_frequency(ctx, &word)? {
                     children.push(child);
                 }
-                children.push(Operation::Query(Query { prefix, kind: typos(word, authorize_typos) }));
+
+                let is_stop_word = ctx.is_stop_word(&word)?;
+                let query = Query { prefix, kind: typos(word, authorize_typos) };
+                if query.prefix || query.kind.is_tolerant() || !is_stop_word {
+                    children.push(Operation::Query(query));
+                }
                 Ok(Operation::or(false, children))
             },
             // create a CONSECUTIVE operation wrapping all word in the phrase
@@ -365,12 +378,11 @@ fn create_query_tree(
         ctx: &impl Context,
         authorize_typos: bool,
         query: &[PrimitiveQueryPart],
-    ) -> anyhow::Result<Operation>
+    ) -> anyhow::Result<Operation> {
-    {
         const MAX_NGRAM: usize = 3;
         let mut op_children = Vec::new();
 
-        for sub_query in query.linear_group_by(|a, b| !(a.is_phrase() || b.is_phrase()) ) {
+        for sub_query in query.linear_group_by(|a, b| !(a.is_phrase() || b.is_phrase())) {
             let mut or_op_children = Vec::new();
 
             for ngram in 1..=MAX_NGRAM.min(sub_query.len()) {
@@ -381,23 +393,31 @@ fn create_query_tree(
 
                     match group {
                         [part] => {
-                            let operation = resolve_primitive_part(ctx, authorize_typos, part.clone())?;
+                            let operation =
+                                resolve_primitive_part(ctx, authorize_typos, part.clone())?;
                             and_op_children.push(operation);
-                        },
+                        }
                         words => {
-                            let is_prefix = words.last().map(|part| part.is_prefix()).unwrap_or(false);
+                            let is_prefix = words.last().map_or(false, |part| part.is_prefix());
-                            let words: Vec<_> = words.iter().filter_map(| part| {
+                            let words: Vec<_> = words
-                                if let PrimitiveQueryPart::Word(word, _) = part {
+                                .iter()
-                                    Some(word.as_str())
+                                .filter_map(|part| {
-                                } else {
+                                    if let PrimitiveQueryPart::Word(word, _) = part {
-                                    None
+                                        Some(word.as_str())
-                                }
+                                    } else {
-                            }).collect();
+                                        None
+                                    }
+                                })
+                                .collect();
                             let mut operations = synonyms(ctx, &words)?.unwrap_or_default();
                             let concat = words.concat();
+
+                            let is_stop_word = ctx.is_stop_word(&concat)?;
                             let query = Query { prefix: is_prefix, kind: typos(concat, authorize_typos) };
-                            operations.push(Operation::Query(query));
+                            if query.prefix || query.kind.is_tolerant() || !is_stop_word {
-                            and_op_children.push(Operation::or(false, operations));
+                                operations.push(Operation::Query(query));
+                                and_op_children.push(Operation::or(false, operations));
+                            }
                         }
                     }
 
@@ -543,7 +563,6 @@ pub fn maximum_proximity(operation: &Operation) -> usize {
 mod test {
     use std::collections::HashMap;
 
-    use fst::Set;
     use maplit::{hashmap, hashset};
     use meilisearch_tokenizer::{Analyzer, AnalyzerConfig};
     use rand::{Rng, SeedableRng, rngs::StdRng};
@@ -582,6 +601,10 @@ mod test {
             let words: Vec<_> = words.iter().map(|s| s.as_ref().to_owned()).collect();
             Ok(self.synonyms.get(&words).cloned())
         }
+
+        fn stop_words(&self) -> anyhow::Result<Option<Set<&[u8]>>> {
+            Ok(None)
+        }
     }
 
     impl Default for TestContext {
@@ -646,8 +669,7 @@ mod test {
     #[test]
     fn prefix() {
         let query = "hey friends";
-        let stop_words = &Set::default();
+        let analyzer = Analyzer::new(AnalyzerConfig::<Vec<u8>>::default());
-        let analyzer = Analyzer::new(AnalyzerConfig::default_with_stopwords(stop_words));
         let result = analyzer.analyze(query);
         let tokens = result.tokens();
 
@@ -667,8 +689,7 @@ mod test {
     #[test]
     fn no_prefix() {
         let query = "hey friends ";
-        let stop_words = &Set::default();
+        let analyzer = Analyzer::new(AnalyzerConfig::<Vec<u8>>::default());
-        let analyzer = Analyzer::new(AnalyzerConfig::default_with_stopwords(stop_words));
         let result = analyzer.analyze(query);
         let tokens = result.tokens();
 
@@ -688,8 +709,7 @@ mod test {
     #[test]
     fn synonyms() {
         let query = "hello world ";
-        let stop_words = &Set::default();
+        let analyzer = Analyzer::new(AnalyzerConfig::<Vec<u8>>::default());
-        let analyzer = Analyzer::new(AnalyzerConfig::default_with_stopwords(stop_words));
         let result = analyzer.analyze(query);
         let tokens = result.tokens();
 
@@ -720,8 +740,7 @@ mod test {
     #[test]
     fn complex_synonyms() {
         let query = "new york city ";
-        let stop_words = &Set::default();
+        let analyzer = Analyzer::new(AnalyzerConfig::<Vec<u8>>::default());
-        let analyzer = Analyzer::new(AnalyzerConfig::default_with_stopwords(stop_words));
         let result = analyzer.analyze(query);
         let tokens = result.tokens();
 
@@ -766,8 +785,7 @@ mod test {
     #[test]
     fn ngrams() {
         let query = "n grams ";
-        let stop_words = &Set::default();
+        let analyzer = Analyzer::new(AnalyzerConfig::<Vec<u8>>::default());
-        let analyzer = Analyzer::new(AnalyzerConfig::default_with_stopwords(stop_words));
         let result = analyzer.analyze(query);
         let tokens = result.tokens();
 
@@ -787,8 +805,7 @@ mod test {
     #[test]
     fn word_split() {
         let query = "wordsplit fish ";
-        let stop_words = &Set::default();
+        let analyzer = Analyzer::new(AnalyzerConfig::<Vec<u8>>::default());
-        let analyzer = Analyzer::new(AnalyzerConfig::default_with_stopwords(stop_words));
         let result = analyzer.analyze(query);
         let tokens = result.tokens();
 
@@ -814,8 +831,7 @@ mod test {
     #[test]
     fn phrase() {
         let query = "\"hey friends\" \" \" \"wooop";
-        let stop_words = &Set::default();
+        let analyzer = Analyzer::new(AnalyzerConfig::<Vec<u8>>::default());
-        let analyzer = Analyzer::new(AnalyzerConfig::default_with_stopwords(stop_words));
         let result = analyzer.analyze(query);
         let tokens = result.tokens();
 
@@ -835,8 +851,7 @@ mod test {
     #[test]
     fn optional_word() {
         let query = "hey my friend ";
-        let stop_words = &Set::default();
+        let analyzer = Analyzer::new(AnalyzerConfig::<Vec<u8>>::default());
-        let analyzer = Analyzer::new(AnalyzerConfig::default_with_stopwords(stop_words));
         let result = analyzer.analyze(query);
         let tokens = result.tokens();
 
@@ -875,8 +890,7 @@ mod test {
     #[test]
     fn optional_word_phrase() {
         let query = "\"hey my\"";
-        let stop_words = &Set::default();
+        let analyzer = Analyzer::new(AnalyzerConfig::<Vec<u8>>::default());
-        let analyzer = Analyzer::new(AnalyzerConfig::default_with_stopwords(stop_words));
         let result = analyzer.analyze(query);
         let tokens = result.tokens();
 
@@ -892,8 +906,7 @@ mod test {
     #[test]
     fn optional_word_multiple_phrases() {
         let query = r#""hey" my good "friend""#;
-        let stop_words = &Set::default();
+        let analyzer = Analyzer::new(AnalyzerConfig::<Vec<u8>>::default());
-        let analyzer = Analyzer::new(AnalyzerConfig::default_with_stopwords(stop_words));
         let result = analyzer.analyze(query);
         let tokens = result.tokens();
 
@@ -927,8 +940,7 @@ mod test {
     #[test]
     fn no_typo() {
         let query = "hey friends ";
-        let stop_words = &Set::default();
+        let analyzer = Analyzer::new(AnalyzerConfig::<Vec<u8>>::default());
-        let analyzer = Analyzer::new(AnalyzerConfig::default_with_stopwords(stop_words));
         let result = analyzer.analyze(query);
         let tokens = result.tokens();
 
@@ -947,8 +959,7 @@ mod test {
     #[test]
     fn fetching_words() {
         let query = "wordsplit nyc world";
-        let stop_words = &Set::default();
+        let analyzer = Analyzer::new(AnalyzerConfig::<Vec<u8>>::default());
-        let analyzer = Analyzer::new(AnalyzerConfig::default_with_stopwords(stop_words));
         let result = analyzer.analyze(query);
         let tokens = result.tokens();
 

milli/src/update/index_documents/mod.rs

@@ -410,6 +410,8 @@ impl<'t, 'u, 'i, 'a> IndexDocuments<'t, 'u, 'i, 'a> {
             None => fields_ids_map.iter().map(|(id, _name)| id).collect(),
         };
 
+        let stop_words = self.index.stop_words(self.wtxn)?;
+        let stop_words = stop_words.as_ref();
         let linked_hash_map_size = self.linked_hash_map_size;
         let max_nb_chunks = self.max_nb_chunks;
         let max_memory = self.max_memory;
@@ -436,7 +438,6 @@ impl<'t, 'u, 'i, 'a> IndexDocuments<'t, 'u, 'i, 'a> {
             let readers = rayon::iter::repeatn(documents, num_threads)
                 .enumerate()
                 .map(|(i, documents)| {
-                    let stop_words = fst::Set::default();
                     let store = Store::new(
                         searchable_fields.clone(),
                         faceted_fields.clone(),
@@ -446,7 +447,7 @@ impl<'t, 'u, 'i, 'a> IndexDocuments<'t, 'u, 'i, 'a> {
                         chunk_compression_type,
                         chunk_compression_level,
                         chunk_fusing_shrink_size,
-                        &stop_words,
+                        stop_words,
                     )?;
                     store.index(
                         documents,

milli/src/update/index_documents/store.rs

@@ -86,7 +86,7 @@ impl<'s, A: AsRef<[u8]>> Store<'s, A> {
         chunk_compression_type: CompressionType,
         chunk_compression_level: Option<u32>,
         chunk_fusing_shrink_size: Option<u64>,
-        stop_words: &'s Set<A>,
+        stop_words: Option<&'s Set<A>>,
     ) -> anyhow::Result<Self>
     {
         // We divide the max memory by the number of sorter the Store have.
@@ -141,7 +141,11 @@ impl<'s, A: AsRef<[u8]>> Store<'s, A> {
             create_writer(chunk_compression_type, chunk_compression_level, f)
         })?;
 
-        let analyzer = Analyzer::new(AnalyzerConfig::default_with_stopwords(stop_words));
+        let mut config = AnalyzerConfig::default();
+        if let Some(stop_words) = stop_words {
+            config.stop_words(stop_words);
+        }
+        let analyzer = Analyzer::new(config);
 
         Ok(Store {
             // Indexing parameters.

milli/src/update/settings.rs

@@ -1,4 +1,4 @@
-use std::collections::HashMap;
+use std::collections::{BTreeSet, HashMap};
 use std::str::FromStr;
 
 use anyhow::Context;
@@ -32,6 +32,7 @@ pub struct Settings<'a, 't, 'u, 'i> {
     displayed_fields: Option<Option<Vec<String>>>,
     faceted_fields: Option<Option<HashMap<String, String>>>,
     criteria: Option<Option<Vec<String>>>,
+    stop_words: Option<Option<BTreeSet<String>>>,
 }
 
 impl<'a, 't, 'u, 'i> Settings<'a, 't, 'u, 'i> {
@@ -55,6 +56,7 @@ impl<'a, 't, 'u, 'i> Settings<'a, 't, 'u, 'i> {
             displayed_fields: None,
             faceted_fields: None,
             criteria: None,
+            stop_words: None,
             update_id,
         }
     }
@@ -91,6 +93,18 @@ impl<'a, 't, 'u, 'i> Settings<'a, 't, 'u, 'i> {
         self.criteria = Some(Some(criteria));
     }
 
+    pub fn reset_stop_words(&mut self) {
+        self.stop_words = Some(None);
+    }
+
+    pub fn set_stop_words(&mut self, stop_words: BTreeSet<String>) {
+        self.stop_words = if stop_words.is_empty() {
+            Some(None)
+        } else {
+            Some(Some(stop_words))
+        }
+    }
+
     fn reindex<F>(&mut self, cb: &F, old_fields_ids_map: FieldsIdsMap) -> anyhow::Result<()>
     where
         F: Fn(UpdateIndexingStep, u64) + Sync
@@ -210,6 +224,28 @@ impl<'a, 't, 'u, 'i> Settings<'a, 't, 'u, 'i> {
         Ok(true)
     }
 
+    fn update_stop_words(&mut self) -> anyhow::Result<bool> {
+        match self.stop_words {
+            Some(Some(ref stop_words)) => {
+                let current = self.index.stop_words(self.wtxn)?;
+                // since we can't compare a BTreeSet with an FST we are going to convert the
+                // BTreeSet to an FST and then compare bytes per bytes the two FSTs.
+                let fst = fst::Set::from_iter(&*stop_words)?;
+
+                // Does the new FST differ from the previous one?
+                if current.map_or(true, |current| current.as_fst().as_bytes() != fst.as_fst().as_bytes()) {
+                    // we want to re-create our FST.
+                    self.index.put_stop_words(self.wtxn, &fst)?;
+                    Ok(true)
+                } else {
+                    Ok(false)
+                }
+            }
+            Some(None) => Ok(self.index.delete_stop_words(self.wtxn)?),
+            None => Ok(false),
+        }
+    }
+
     fn update_facets(&mut self) -> anyhow::Result<bool> {
         match self.faceted_fields {
             Some(Some(ref fields)) => {
@@ -248,22 +284,23 @@ impl<'a, 't, 'u, 'i> Settings<'a, 't, 'u, 'i> {
 
     pub fn execute<F>(mut self, progress_callback: F) -> anyhow::Result<()>
     where
-        F: Fn(UpdateIndexingStep, u64) + Sync
+    F: Fn(UpdateIndexingStep, u64) + Sync
-        {
+    {
-            self.index.set_updated_at(self.wtxn, &Utc::now())?;
+        self.index.set_updated_at(self.wtxn, &Utc::now())?;
-            let old_fields_ids_map = self.index.fields_ids_map(&self.wtxn)?;
+        let old_fields_ids_map = self.index.fields_ids_map(&self.wtxn)?;
-            self.update_displayed()?;
+        self.update_displayed()?;
-            let facets_updated = self.update_facets()?;
+        let stop_words_updated = self.update_stop_words()?;
-            // update_criteria MUST be called after update_facets, since criterion fields must be set
+        let facets_updated = self.update_facets()?;
-            // as facets.
+        // update_criteria MUST be called after update_facets, since criterion fields must be set
-            self.update_criteria()?;
+        // as facets.
-            let searchable_updated = self.update_searchable()?;
+        self.update_criteria()?;
+        let searchable_updated = self.update_searchable()?;
 
-            if facets_updated || searchable_updated {
+        if facets_updated || searchable_updated || stop_words_updated {
-                self.reindex(&progress_callback, old_fields_ids_map)?;
+            self.reindex(&progress_callback, old_fields_ids_map)?;
-            }
-            Ok(())
         }
+        Ok(())
+    }
 }
 
 #[cfg(test)]
@@ -271,7 +308,7 @@ mod tests {
     use super::*;
 
     use heed::EnvOpenOptions;
-    use maplit::hashmap;
+    use maplit::{hashmap, btreeset};
 
     use crate::facet::FacetType;
     use crate::update::{IndexDocuments, UpdateFormat};
@@ -328,7 +365,6 @@ mod tests {
         assert_eq!(result.documents_ids.len(), 1);
         let documents = index.documents(&rtxn, result.documents_ids).unwrap();
         assert_eq!(documents[0].1.get(0), Some(&br#""kevin""#[..]));
-        drop(rtxn);
     }
 
     #[test]
@@ -372,7 +408,6 @@ mod tests {
         let rtxn = index.read_txn().unwrap();
         let fields_ids = index.displayed_fields(&rtxn).unwrap();
         assert_eq!(fields_ids.unwrap(), &["age"][..]);
-        drop(rtxn);
     }
 
     #[test]
@@ -394,7 +429,6 @@ mod tests {
         let rtxn = index.read_txn().unwrap();
         let fields_ids = index.displayed_fields(&rtxn).unwrap();
         assert_eq!(fields_ids, None);
-        drop(rtxn);
     }
 
     #[test]
@@ -434,7 +468,6 @@ mod tests {
         let rtxn = index.read_txn().unwrap();
         let fields_ids = index.displayed_fields(&rtxn).unwrap();
         assert_eq!(fields_ids, None);
-        drop(rtxn);
     }
 
     #[test]
@@ -478,7 +511,96 @@ mod tests {
         // Only count the field_id 0 and level 0 facet values.
         let count = index.facet_field_id_value_docids.prefix_iter(&rtxn, &[0, 0]).unwrap().count();
         assert_eq!(count, 4);
-        drop(rtxn);
+    }
+
+    #[test]
+    fn default_stop_words() {
+        let path = tempfile::tempdir().unwrap();
+        let mut options = EnvOpenOptions::new();
+        options.map_size(10 * 1024 * 1024); // 10 MB
+        let index = Index::new(options, &path).unwrap();
+
+        // First we send 3 documents with ids from 1 to 3.
+        let mut wtxn = index.write_txn().unwrap();
+        let content = &b"name,age\nkevin,23\nkevina,21\nbenoit,34\n"[..];
+        let mut builder = IndexDocuments::new(&mut wtxn, &index, 0);
+        builder.update_format(UpdateFormat::Csv);
+        builder.execute(content, |_, _| ()).unwrap();
+        wtxn.commit().unwrap();
+
+        // Ensure there is no stop_words by default
+        let rtxn = index.read_txn().unwrap();
+        let stop_words = index.stop_words(&rtxn).unwrap();
+        assert!(stop_words.is_none());
+    }
+
+    #[test]
+    fn set_and_reset_stop_words() {
+        let path = tempfile::tempdir().unwrap();
+        let mut options = EnvOpenOptions::new();
+        options.map_size(10 * 1024 * 1024); // 10 MB
+        let index = Index::new(options, &path).unwrap();
+
+        // First we send 3 documents with ids from 1 to 3.
+        let mut wtxn = index.write_txn().unwrap();
+        let content = &b"name,age,maxim\nkevin,23,I love dogs\nkevina,21,Doggos are the best\nbenoit,34,The crepes are really good\n"[..];
+        let mut builder = IndexDocuments::new(&mut wtxn, &index, 0);
+        builder.update_format(UpdateFormat::Csv);
+        builder.execute(content, |_, _| ()).unwrap();
+
+        // In the same transaction we provide some stop_words
+        let mut builder = Settings::new(&mut wtxn, &index, 0);
+        let set = btreeset!{ "i".to_string(), "the".to_string(), "are".to_string() };
+        builder.set_stop_words(set.clone());
+        builder.execute(|_, _| ()).unwrap();
+        wtxn.commit().unwrap();
+
+        // Ensure stop_words are effectively stored
+        let rtxn = index.read_txn().unwrap();
+        let stop_words = index.stop_words(&rtxn).unwrap();
+        assert!(stop_words.is_some()); // at this point the index should return something
+
+        let stop_words = stop_words.unwrap();
+        let expected = fst::Set::from_iter(&set).unwrap();
+        assert_eq!(stop_words.as_fst().as_bytes(), expected.as_fst().as_bytes());
+
+        // when we search for something that is a non prefix stop_words it should be ignored
+        let result = index.search(&rtxn).query("the ").execute().unwrap();
+        assert!(result.documents_ids.is_empty());
+        let result = index.search(&rtxn).query("i ").execute().unwrap();
+        assert!(result.documents_ids.is_empty());
+        let result = index.search(&rtxn).query("are ").execute().unwrap();
+        assert!(result.documents_ids.is_empty());
+
+        let result = index.search(&rtxn).query("dog").execute().unwrap();
+        assert_eq!(result.documents_ids.len(), 2); // we have two maxims talking about doggos
+        let result = index.search(&rtxn).query("benoît").execute().unwrap();
+        assert_eq!(result.documents_ids.len(), 1); // there is one benoit in our data
+
+        // now we'll reset the stop_words and ensure it's None
+        let mut wtxn = index.write_txn().unwrap();
+        let mut builder = Settings::new(&mut wtxn, &index, 0);
+        builder.reset_stop_words();
+        builder.execute(|_, _| ()).unwrap();
+        wtxn.commit().unwrap();
+
+        let rtxn = index.read_txn().unwrap();
+        let stop_words = index.stop_words(&rtxn).unwrap();
+        assert!(stop_words.is_none());
+
+        // now we can search for the stop words
+        let result = index.search(&rtxn).query("the").execute().unwrap();
+        assert_eq!(result.documents_ids.len(), 2);
+        let result = index.search(&rtxn).query("i").execute().unwrap();
+        assert_eq!(result.documents_ids.len(), 1);
+        let result = index.search(&rtxn).query("are").execute().unwrap();
+        assert_eq!(result.documents_ids.len(), 2);
+
+        // the rest of the search is still not impacted
+        let result = index.search(&rtxn).query("dog").execute().unwrap();
+        assert_eq!(result.documents_ids.len(), 2); // we have two maxims talking about doggos
+        let result = index.search(&rtxn).query("benoît").execute().unwrap();
+        assert_eq!(result.documents_ids.len(), 1); // there is one benoit in our data
     }
 
     #[test]
@@ -519,6 +641,5 @@ mod tests {
         assert_eq!(&["hello"][..], index.displayed_fields(&rtxn).unwrap().unwrap());
         assert!(index.primary_key(&rtxn).unwrap().is_none());
         assert_eq!(vec![Criterion::Asc("toto".to_string())], index.criteria(&rtxn).unwrap());
-        drop(rtxn);
     }
 }