Adapt prefix thresholds

milli/src/search/new/tests/proximity.rs

@@ -371,21 +371,21 @@ fn test_proximity_prefix_db() {
     s.scoring_strategy(crate::score_details::ScoringStrategy::Detailed);
     s.query("best s");
     let SearchResult { documents_ids, document_scores, .. } = s.execute().unwrap();
-    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[10, 9, 6, 7, 8, 11, 12, 13, 15]");
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[10, 13, 9, 12, 6, 7, 8, 11, 15]");
     insta::assert_snapshot!(format!("{document_scores:#?}"));
     let texts = collect_field_values(&index, &txn, "text", &documents_ids);
 
     // This test illustrates the loss of precision from using the prefix DB
     insta::assert_debug_snapshot!(texts, @r###"
     [
         "\"this is the best summer meal\"",
+        "\"summer best\"",
         "\"this is the best meal of summer\"",
+        "\"summer x best\"",
         "\"this is the best meal I have ever had in such a beautiful summer day\"",
         "\"this is the best cooked meal of the summer\"",
         "\"this is the best meal of the summer\"",
         "\"summer x y best\"",
-        "\"summer x best\"",
-        "\"summer best\"",
         "\"this is the best meal I have ever had in such a beautiful winter day\"",
     ]
     "###);
@@ -423,20 +423,20 @@ fn test_proximity_prefix_db() {
     s.scoring_strategy(crate::score_details::ScoringStrategy::Detailed);
     s.query("best win");
     let SearchResult { documents_ids, document_scores, .. } = s.execute().unwrap();
-    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[19, 18, 15, 16, 17, 20, 21, 22]");
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[19, 22, 18, 21, 15, 16, 17, 20]");
     insta::assert_snapshot!(format!("{document_scores:#?}"));
     let texts = collect_field_values(&index, &txn, "text", &documents_ids);
 
     insta::assert_debug_snapshot!(texts, @r###"
     [
         "\"this is the best winter meal\"",
+        "\"winter best\"",
         "\"this is the best meal of winter\"",
+        "\"winter x best\"",
         "\"this is the best meal I have ever had in such a beautiful winter day\"",
         "\"this is the best cooked meal of the winter\"",
         "\"this is the best meal of the winter\"",
         "\"winter x y best\"",
-        "\"winter x best\"",
-        "\"winter best\"",
     ]
     "###);
 
@@ -471,20 +471,20 @@ fn test_proximity_prefix_db() {
     s.scoring_strategy(crate::score_details::ScoringStrategy::Detailed);
     s.query("best wi");
     let SearchResult { documents_ids, document_scores, .. } = s.execute().unwrap();
-    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[19, 18, 15, 16, 17, 20, 21, 22]");
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[19, 22, 18, 21, 15, 16, 17, 20]");
     insta::assert_snapshot!(format!("{document_scores:#?}"));
     let texts = collect_field_values(&index, &txn, "text", &documents_ids);
 
     insta::assert_debug_snapshot!(texts, @r###"
     [
         "\"this is the best winter meal\"",
+        "\"winter best\"",
         "\"this is the best meal of winter\"",
+        "\"winter x best\"",
         "\"this is the best meal I have ever had in such a beautiful winter day\"",
         "\"this is the best cooked meal of the winter\"",
         "\"this is the best meal of the winter\"",
         "\"winter x y best\"",
-        "\"winter x best\"",
-        "\"winter best\"",
     ]
     "###);
 }

milli/src/search/new/tests/snapshots/milli__search__new__tests__proximity__proximity_prefix_db-14.snap

@@ -14,23 +14,23 @@ expression: "format!(\"{document_scores:#?}\")"
     [
         Proximity(
             Rank {
-                rank: 2,
+                rank: 3,
                 max_rank: 4,
             },
         ),
     ],
     [
         Proximity(
             Rank {
-                rank: 1,
+                rank: 2,
                 max_rank: 4,
             },
         ),
     ],
     [
         Proximity(
             Rank {
-                rank: 1,
+                rank: 2,
                 max_rank: 4,
             },
         ),

milli/src/search/new/tests/snapshots/milli__search__new__tests__proximity__proximity_prefix_db-2.snap

@@ -14,23 +14,23 @@ expression: "format!(\"{document_scores:#?}\")"
     [
         Proximity(
             Rank {
-                rank: 2,
+                rank: 3,
                 max_rank: 4,
             },
         ),
     ],
     [
         Proximity(
             Rank {
-                rank: 1,
+                rank: 2,
                 max_rank: 4,
             },
         ),
     ],
     [
         Proximity(
             Rank {
-                rank: 1,
+                rank: 2,
                 max_rank: 4,
             },
         ),

milli/src/search/new/tests/snapshots/milli__search__new__tests__proximity__proximity_prefix_db-8.snap

@@ -14,23 +14,23 @@ expression: "format!(\"{document_scores:#?}\")"
     [
         Proximity(
             Rank {
-                rank: 2,
+                rank: 3,
                 max_rank: 4,
             },
         ),
     ],
     [
         Proximity(
             Rank {
-                rank: 1,
+                rank: 2,
                 max_rank: 4,
             },
         ),
     ],
     [
         Proximity(
             Rank {
-                rank: 1,
+                rank: 2,
                 max_rank: 4,
             },
         ),

milli/src/update/words_prefixes_fst.rs

@@ -15,7 +15,7 @@ pub struct WordsPrefixesFst<'t, 'i> {
 
 impl<'t, 'i> WordsPrefixesFst<'t, 'i> {
     pub fn new(wtxn: &'t mut RwTxn<'i>, index: &'i Index) -> WordsPrefixesFst<'t, 'i> {
-        WordsPrefixesFst { wtxn, index, threshold: 100, max_prefix_length: 4 }
+        WordsPrefixesFst { wtxn, index, threshold: 500, max_prefix_length: 3 }
     }
 
     /// Set the number of words required to make a prefix be part of the words prefixes