From 4c65c8affa0c670dd0db040a12509ce3df514530 Mon Sep 17 00:00:00 2001
From: carlosdelest <carlos.delgado@elastic.co>
Date: Thu, 5 Dec 2024 21:55:48 +0100
Subject: [PATCH] Fix sneaky bug on iterator

---
 .../mapper/vectors/VectorSimilarityFloatValueSource.java    | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/server/src/main/java/org/elasticsearch/index/mapper/vectors/VectorSimilarityFloatValueSource.java b/server/src/main/java/org/elasticsearch/index/mapper/vectors/VectorSimilarityFloatValueSource.java
index 540533a1b2b7d..04b2a906d6dad 100644
--- a/server/src/main/java/org/elasticsearch/index/mapper/vectors/VectorSimilarityFloatValueSource.java
+++ b/server/src/main/java/org/elasticsearch/index/mapper/vectors/VectorSimilarityFloatValueSource.java
@@ -50,18 +50,14 @@ public DoubleValues getValues(LeafReaderContext ctx, DoubleValues scores) throws
         final KnnVectorValues.DocIndexIterator iterator = vectorValues.iterator();
 
         return new DoubleValues() {
-            private int docId = -1;
-
             @Override
             public double doubleValue() throws IOException {
                 vectorOpsCount++;
-                return vectorSimilarityFunction.compare(target, vectorValues.vectorValue(docId));
+                return vectorSimilarityFunction.compare(target, vectorValues.vectorValue(iterator.index()));
             }
 
             @Override
             public boolean advanceExact(int doc) throws IOException {
-                assert doc > iterator.docID();
-                docId = doc;
                 return doc >= iterator.docID() && iterator.docID() != DocIdSetIterator.NO_MORE_DOCS && iterator.advance(doc) == doc;
             }
         };