Introduce a special word_derivations function for Proximity

milli/src/search/criteria/mod.rs

@@ -67,7 +67,7 @@ pub trait Context {
     fn word_prefix_pair_proximity_docids(&self, left: &str, right: &str, proximity: u8) -> heed::Result<Option<RoaringBitmap>>;
     fn words_fst<'t>(&self) -> &'t fst::Set<Cow<[u8]>>;
     fn in_prefix_cache(&self, word: &str) -> bool;
-    fn docid_word_positions(&self, docid: DocumentId, word: &str) -> heed::Result<Option<RoaringBitmap>>;
+    fn docid_words_positions(&self, docid: DocumentId) -> heed::Result<HashMap<String, RoaringBitmap>>;
 }
 pub struct CriteriaBuilder<'t> {
     rtxn: &'t heed::RoTxn<'t>,
@@ -107,9 +107,13 @@ impl<'a> Context for CriteriaBuilder<'a> {
         self.words_prefixes_fst.contains(word)
     }
 
-    fn docid_word_positions(&self, docid: DocumentId, word: &str) -> heed::Result<Option<RoaringBitmap>> {
+    fn docid_words_positions(&self, docid: DocumentId) -> heed::Result<HashMap<String, RoaringBitmap>> {
-        let key = (docid, word);
+        let mut words_positions = HashMap::new();
-        self.index.docid_word_positions.get(self.rtxn, &key)
+        for result in self.index.docid_word_positions.prefix_iter(self.rtxn, &(docid, ""))? {
+            let ((_, word), positions) = result?;
+            words_positions.insert(word.to_string(), positions);
+        }
+        Ok(words_positions)
     }
 }
 
@@ -391,7 +395,7 @@ pub mod test {
             self.word_prefix_docids.contains_key(&word.to_string())
         }
 
-        fn docid_word_positions(&self, _docid: DocumentId, _word: &str) -> heed::Result<Option<RoaringBitmap>> {
+        fn docid_words_positions(&self, _docid: DocumentId) -> heed::Result<HashMap<String, RoaringBitmap>> {
             todo!()
         }
     }

milli/src/search/criteria/proximity.rs

@@ -1,14 +1,13 @@
-use std::borrow::Cow;
 use std::collections::btree_map::{self, BTreeMap};
-use std::collections::hash_map::{HashMap, Entry};
+use std::collections::hash_map::HashMap;
 use std::mem::take;
 
 use roaring::RoaringBitmap;
 use log::debug;
 
-use crate::{DocumentId, Position, search::{query_tree::QueryKind, word_derivations}};
+use crate::{DocumentId, Position, search::{query_tree::QueryKind}};
 use crate::search::query_tree::{maximum_proximity, Operation, Query};
-use crate::search::WordDerivationsCache;
+use crate::search::{build_dfa, WordDerivationsCache};
 use super::{Candidates, Criterion, CriterionResult, Context, query_docids, query_pair_proximity_docids, resolve_query_tree};
 
 pub struct Proximity<'t> {
@@ -358,7 +357,7 @@ fn resolve_plane_sweep_candidates(
         docid: DocumentId,
         consecutive: bool,
         rocache: &mut HashMap<&'a Operation, Vec<(Position, u8, Position)>>,
-        dwpcache: &mut HashMap<String, Option<RoaringBitmap>>,
+        words_positions: &HashMap<String, RoaringBitmap>,
         wdcache: &mut WordDerivationsCache,
     ) -> anyhow::Result<Vec<(Position, u8, Position)>>
     {
@@ -400,7 +399,7 @@ fn resolve_plane_sweep_candidates(
         let mut groups_positions = Vec::with_capacity(groups_len);
 
         for operation in operations {
-            let positions = resolve_operation(ctx, operation, docid, rocache, dwpcache, wdcache)?;
+            let positions = resolve_operation(ctx, operation, docid, rocache, words_positions, wdcache)?;
             groups_positions.push(positions.into_iter());
         }
 
@@ -476,7 +475,7 @@ fn resolve_plane_sweep_candidates(
         query_tree: &'a Operation,
         docid: DocumentId,
         rocache: &mut HashMap<&'a Operation, Vec<(Position, u8, Position)>>,
-        dwpcache: &mut HashMap<String, Option<RoaringBitmap>>,
+        words_positions: &HashMap<String, RoaringBitmap>,
         wdcache: &mut WordDerivationsCache,
     ) -> anyhow::Result<Vec<(Position, u8, Position)>>
     {
@@ -487,44 +486,34 @@ fn resolve_plane_sweep_candidates(
         }
 
         let result = match query_tree {
-            And(ops) => plane_sweep(ctx, ops, docid, false, rocache, dwpcache, wdcache)?,
+            And(ops) => plane_sweep(ctx, ops, docid, false, rocache, words_positions, wdcache)?,
-            Consecutive(ops) => plane_sweep(ctx, ops, docid, true, rocache, dwpcache, wdcache)?,
+            Consecutive(ops) => plane_sweep(ctx, ops, docid, true, rocache, words_positions, wdcache)?,
             Or(_, ops) => {
                 let mut result = Vec::new();
                 for op in ops {
-                    result.extend(resolve_operation(ctx, op, docid, rocache, dwpcache, wdcache)?)
+                    result.extend(resolve_operation(ctx, op, docid, rocache, words_positions, wdcache)?)
                 }
 
                 result.sort_unstable();
                 result
             },
             Operation::Query(Query { prefix, kind }) => {
-                let fst = ctx.words_fst();
+                let mut result = Vec::new();
-                let words = match kind {
+                match kind {
                     QueryKind::Exact { word, .. } => {
                         if *prefix {
-                            Cow::Borrowed(word_derivations(word, true, 0, fst, wdcache)?)
+                            let iter = word_derivations(word, true, 0, &words_positions)
+                                .flat_map(|positions| positions.iter().map(|p| (p, 0, p)));
+                            result.extend(iter);
                         } else {
-                            Cow::Owned(vec![(word.to_string(), 0)])
+                            if let Some(positions) = words_positions.get(word) {
+                                result.extend(positions.iter().map(|p| (p, 0, p)));
+                            }
                         }
                     },
                     QueryKind::Tolerant { typo, word } => {
-                        Cow::Borrowed(word_derivations(word, *prefix, *typo, fst, wdcache)?)
+                        let iter = word_derivations(word, *prefix, *typo, &words_positions)
-                    }
+                            .flat_map(|positions| positions.iter().map(|p| (p, 0, p)));
-                };
-
-                let mut result = Vec::new();
-                for (word, _) in words.as_ref() {
-                    let positions = match dwpcache.entry(word.to_string()) {
-                        Entry::Occupied(entry) => entry.into_mut(),
-                        Entry::Vacant(entry) => {
-                            let positions = ctx.docid_word_positions(docid, word)?;
-                            entry.insert(positions)
-                        }
-                    };
-
-                    if let Some(positions) = positions {
-                        let iter = positions.iter().map(|p| (p, 0, p));
                         result.extend(iter);
                     }
                 }
@@ -538,18 +527,34 @@ fn resolve_plane_sweep_candidates(
         Ok(result)
     }
 
-    let mut word_positions_cache = HashMap::new();
+    fn word_derivations<'a>(
+        word: &str,
+        is_prefix: bool,
+        max_typo: u8,
+        words_positions: &'a HashMap<String, RoaringBitmap>,
+    ) -> impl Iterator<Item = &'a RoaringBitmap>
+    {
+        let dfa = build_dfa(word, max_typo, is_prefix);
+        words_positions.iter().filter_map(move |(document_word, positions)| {
+            use levenshtein_automata::Distance;
+            match dfa.eval(document_word) {
+                Distance::Exact(_) => Some(positions),
+                Distance::AtLeast(_) => None,
+            }
+        })
+    }
+
     let mut resolve_operation_cache = HashMap::new();
     let mut candidates = BTreeMap::new();
     for docid in allowed_candidates {
-        word_positions_cache.clear();
+        let words_positions = ctx.docid_words_positions(docid)?;
         resolve_operation_cache.clear();
         let positions =  resolve_operation(
             ctx,
             query_tree,
             docid,
             &mut resolve_operation_cache,
-            &mut word_positions_cache,
+            &words_positions,
             wdcache,
         )?;
         let best_proximity = positions.into_iter().min_by_key(|(_, proximity, _)| *proximity);