From c701f8bf36fbba25413f00ab1e8ebf7abeefb0a4 Mon Sep 17 00:00:00 2001
From: many <maxime@meilisearch.com>
Date: Thu, 27 May 2021 15:32:14 +0200
Subject: [PATCH] Use field id word count database in exactness criterion

---
 milli/src/search/criteria/exactness.rs | 4 ++--
 milli/src/search/criteria/mod.rs       | 9 +++++----
 2 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/milli/src/search/criteria/exactness.rs b/milli/src/search/criteria/exactness.rs
index b1026ccc2..7f27287b7 100644
--- a/milli/src/search/criteria/exactness.rs
+++ b/milli/src/search/criteria/exactness.rs
@@ -162,11 +162,11 @@ fn resolve_state(
     use State::*;
     match state {
         ExactAttribute(mut allowed_candidates) => {
-            let query_len = query.len() as u32;
+            let query_len = query.len() as u8;
             let mut candidates = RoaringBitmap::new();
             let attributes_ids = ctx.searchable_fields_ids()?;
             for id in attributes_ids {
-                if let Some(attribute_allowed_docids) = ctx.field_id_len_docids(id, query_len)? {
+                if let Some(attribute_allowed_docids) = ctx.field_id_word_count_docids(id, query_len)? {
                     let mut attribute_candidates_array = attribute_start_with_docids(ctx, id as u32, query)?;
                     attribute_candidates_array.push(attribute_allowed_docids);
                     candidates |= intersection_of(attribute_candidates_array.iter().collect());
diff --git a/milli/src/search/criteria/mod.rs b/milli/src/search/criteria/mod.rs
index 99e4a4209..456d16e1a 100644
--- a/milli/src/search/criteria/mod.rs
+++ b/milli/src/search/criteria/mod.rs
@@ -78,7 +78,7 @@ pub trait Context<'c> {
     fn word_position_last_level(&self, word: &str, in_prefix_cache: bool) -> heed::Result<Option<TreeLevel>>;
     fn synonyms(&self, word: &str) -> heed::Result<Option<Vec<Vec<String>>>>;
     fn searchable_fields_ids(&self) ->  heed::Result<Vec<FieldId>>;
-    fn field_id_len_docids(&self, field_id: FieldId, len: u32) -> heed::Result<Option<RoaringBitmap>>;
+    fn field_id_word_count_docids(&self, field_id: FieldId, word_count: u8) -> heed::Result<Option<RoaringBitmap>>;
     fn word_level_position_docids(&self, word: &str, level: TreeLevel, left: u32, right: u32) -> Result<Option<RoaringBitmap>, heed::Error>;
 }
 pub struct CriteriaBuilder<'t> {
@@ -181,8 +181,9 @@ impl<'c> Context<'c> for CriteriaBuilder<'c> {
         }
     }
 
-    fn field_id_len_docids(&self, _field_id: FieldId, _len: u32) -> heed::Result<Option<RoaringBitmap>> {
-        Ok(None)
+    fn field_id_word_count_docids(&self, field_id: FieldId, word_count: u8) -> heed::Result<Option<RoaringBitmap>> {
+        let key = (field_id, word_count);
+        self.index.field_id_word_count_docids.get(self.rtxn, &key)
     }
 
     fn word_level_position_docids(&self, word: &str, level: TreeLevel, left: u32, right: u32) -> Result<Option<RoaringBitmap>, heed::Error> {
@@ -488,7 +489,7 @@ pub mod test {
             todo!()
         }
 
-        fn field_id_len_docids(&self, _field_id: FieldId, _len: u32) -> heed::Result<Option<RoaringBitmap>> {
+        fn field_id_word_count_docids(&self, _field_id: FieldId, _word_count: u8) -> heed::Result<Option<RoaringBitmap>> {
             todo!()
         }
     }