DiskBBQ - missing min competitive similarity check on tail docs (#135851)

Author: tteofili

docs/changelog/135851.yaml

@@ -0,0 +1,5 @@
+pr: 135851
+summary: DiskBBQ - missing min competitive similarity check on tail docs
+area: Vector Search
+type: bug
+issues: []

server/src/main/java/org/elasticsearch/index/codec/vectors/diskbbq/ES920DiskBBQVectorsReader.java

@@ -568,7 +568,9 @@ public int visit(KnnCollector knnCollector) throws IOException {
                         qcDist
                     );
                     scoredDocs++;
-                    knnCollector.collect(doc, score);
+                    if (knnCollector.minCompetitiveSimilarity() < score) {
+                        knnCollector.collect(doc, score);
+                    }
                 } else {
                     indexInput.skipBytes(quantizedByteLength);
                 }