Fix failed tests and rebase on main branch

Signed-off-by: Wei Wang <[email protected]>

CHANGELOG.md

@@ -23,6 +23,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Introduced a writing layer in native engines where relies on the writing interface to process IO. (#2241)[https://github.com/opensearch-project/k-NN/pull/2241]
 - Allow method parameter override for training based indices (#2290) https://github.com/opensearch-project/k-NN/pull/2290]
 - Optimizes lucene query execution to prevent unnecessary rewrites (#2305)[https://github.com/opensearch-project/k-NN/pull/2305]
+- Add check to directly use ANN Search when filters match all docs. (#2320)[https://github.com/opensearch-project/k-NN/pull/2320]
 ### Bug Fixes
 * Fixing the bug when a segment has no vector field present for disk based vector search (#2282)[https://github.com/opensearch-project/k-NN/pull/2282]
 * Allow validation for non knn index only after 2.17.0 (#2315)[https://github.com/opensearch-project/k-NN/pull/2315]

src/main/java/org/opensearch/knn/index/query/KNNWeight.java

@@ -131,12 +131,6 @@ public PerLeafResult searchLeaf(LeafReaderContext context, int k) throws IOExcep
         final BitSet filterBitSet = getFilteredDocsBitSet(context);
         final int maxDoc = context.reader().maxDoc();
         int cardinality = filterBitSet.cardinality();
-        /*
-        * If filters match all docs in this segment, then there is no need to do any extra step
-        * and should directly do ANN Search*/
-        if (cardinality ==  maxDoc){
-            return doANNSearch(context, filterBitSet, cardinality, k);
-        }
         // We don't need to go to JNI layer if no documents are found which satisfy the filters
         // We should give this condition a deeper look that where it should be placed. For now I feel this is a good
         // place,
@@ -156,7 +150,7 @@ public PerLeafResult searchLeaf(LeafReaderContext context, int k) throws IOExcep
          * If filters match all docs in this segment, then there is no need to do any extra step
          * and should directly do ANN Search*/
         if (filterWeight != null && cardinality == maxDoc) {
-            return doANNSearch(context, new FixedBitSet(0), 0, k);
+            return new PerLeafResult(filterBitSet, doANNSearch(context, filterBitSet, cardinality, k));
         }
         Map<Integer, Float> docIdsToScoreMap = doANNSearch(context, filterBitSet, cardinality, k);
         // See whether we have to perform exact search based on approx search results