diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3a5fda2a21..a19b53fd84 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -26,6 +26,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 ### 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]
+* Release query vector memory after execution (#2346)[https://github.com/opensearch-project/k-NN/pull/2346]
+* Fix shard level rescoring disabled setting flag (#2352)[https://github.com/opensearch-project/k-NN/pull/2352]
 ### Infrastructure
 * Updated C++ version in JNI from c++11 to c++17 [#2259](https://github.com/opensearch-project/k-NN/pull/2259)
 * Upgrade bytebuddy and objenesis version to match OpenSearch core and, update github ci runner for macos [#2279](https://github.com/opensearch-project/k-NN/pull/2279)
diff --git a/jni/src/faiss_wrapper.cpp b/jni/src/faiss_wrapper.cpp
index 98c40cf6b3..c02c410c1f 100644
--- a/jni/src/faiss_wrapper.cpp
+++ b/jni/src/faiss_wrapper.cpp
@@ -1180,6 +1180,7 @@ jobjectArray knn_jni::faiss_wrapper::RangeSearchWithFilter(knn_jni::JNIUtilInter
             jniUtil->ReleaseLongArrayElements(env, filterIdsJ, filteredIdsArray, JNI_ABORT);
             throw;
         }
+        jniUtil->ReleaseLongArrayElements(env, filterIdsJ, filteredIdsArray, JNI_ABORT);
     } else {
         faiss::SearchParameters *searchParameters = nullptr;
         faiss::SearchParametersHNSW hnswParams;
@@ -1202,6 +1203,7 @@ jobjectArray knn_jni::faiss_wrapper::RangeSearchWithFilter(knn_jni::JNIUtilInter
             throw;
         }
     }
+    jniUtil->ReleaseFloatArrayElements(env, queryVectorJ, rawQueryVector, JNI_ABORT);
 
     // lims is structured to support batched queries, it has a length of nq + 1 (where nq is the number of queries),
     // lims[i] - lims[i-1] gives the number of results for the i-th query. With a single query we used in k-NN,
diff --git a/qa/restart-upgrade/src/test/java/org/opensearch/knn/bwc/AbstractRestartUpgradeTestCase.java b/qa/restart-upgrade/src/test/java/org/opensearch/knn/bwc/AbstractRestartUpgradeTestCase.java
index e79e2abefd..4ba1fe03aa 100644
--- a/qa/restart-upgrade/src/test/java/org/opensearch/knn/bwc/AbstractRestartUpgradeTestCase.java
+++ b/qa/restart-upgrade/src/test/java/org/opensearch/knn/bwc/AbstractRestartUpgradeTestCase.java
@@ -61,4 +61,13 @@ protected static final boolean isRunningAgainstOldCluster() {
     protected final Optional<String> getBWCVersion() {
         return Optional.ofNullable(System.getProperty(BWC_VERSION, null));
     }
+
+    @Override
+    protected Settings getKNNDefaultIndexSettings() {
+        if (isApproximateThresholdSupported(getBWCVersion())) {
+            return super.getKNNDefaultIndexSettings();
+        }
+        // for bwc will return old default setting without approximate value threshold setting
+        return getDefaultIndexSettings();
+    }
 }
diff --git a/qa/rolling-upgrade/src/test/java/org/opensearch/knn/bwc/AbstractRollingUpgradeTestCase.java b/qa/rolling-upgrade/src/test/java/org/opensearch/knn/bwc/AbstractRollingUpgradeTestCase.java
index 235e3e4df3..16e4a9c3d2 100644
--- a/qa/rolling-upgrade/src/test/java/org/opensearch/knn/bwc/AbstractRollingUpgradeTestCase.java
+++ b/qa/rolling-upgrade/src/test/java/org/opensearch/knn/bwc/AbstractRollingUpgradeTestCase.java
@@ -85,4 +85,13 @@ protected final Optional<String> getBWCVersion() {
         return Optional.ofNullable(System.getProperty(BWC_VERSION, null));
     }
 
+    @Override
+    protected Settings getKNNDefaultIndexSettings() {
+        if (isApproximateThresholdSupported(getBWCVersion())) {
+            return super.getKNNDefaultIndexSettings();
+        }
+        // for bwc will return old default setting without approximate value threshold setting
+        return getDefaultIndexSettings();
+    }
+
 }
diff --git a/qa/rolling-upgrade/src/test/java/org/opensearch/knn/bwc/IndexingIT.java b/qa/rolling-upgrade/src/test/java/org/opensearch/knn/bwc/IndexingIT.java
index d0ee16c99f..c4bf6082cf 100644
--- a/qa/rolling-upgrade/src/test/java/org/opensearch/knn/bwc/IndexingIT.java
+++ b/qa/rolling-upgrade/src/test/java/org/opensearch/knn/bwc/IndexingIT.java
@@ -22,7 +22,7 @@ public void testKNNDefaultIndexSettings() throws Exception {
         waitForClusterHealthGreen(NODES_BWC_CLUSTER);
         switch (getClusterType()) {
             case OLD:
-                createKnnIndex(testIndex, getKNNDefaultIndexSettings(), createKnnIndexMapping(TEST_FIELD, DIMENSIONS));
+                createKnnIndex(testIndex, getDefaultIndexSettings(), createKnnIndexMapping(TEST_FIELD, DIMENSIONS));
                 int docIdOld = 0;
                 addKNNDocs(testIndex, TEST_FIELD, DIMENSIONS, docIdOld, NUM_DOCS);
                 break;
diff --git a/src/main/java/org/opensearch/knn/index/KNNSettings.java b/src/main/java/org/opensearch/knn/index/KNNSettings.java
index b81a541248..6dc72a22bd 100644
--- a/src/main/java/org/opensearch/knn/index/KNNSettings.java
+++ b/src/main/java/org/opensearch/knn/index/KNNSettings.java
@@ -577,7 +577,7 @@ public static Integer getFilteredExactSearchThreshold(final String indexName) {
             .getAsInt(ADVANCED_FILTERED_EXACT_SEARCH_THRESHOLD, ADVANCED_FILTERED_EXACT_SEARCH_THRESHOLD_DEFAULT_VALUE);
     }
 
-    public static boolean isShardLevelRescoringEnabledForDiskBasedVector(String indexName) {
+    public static boolean isShardLevelRescoringDisabledForDiskBasedVector(String indexName) {
         return KNNSettings.state().clusterService.state()
             .getMetadata()
             .index(indexName)
diff --git a/src/main/java/org/opensearch/knn/index/query/nativelib/NativeEngineKnnVectorQuery.java b/src/main/java/org/opensearch/knn/index/query/nativelib/NativeEngineKnnVectorQuery.java
index 47ea215f35..5b4d6e7a1d 100644
--- a/src/main/java/org/opensearch/knn/index/query/nativelib/NativeEngineKnnVectorQuery.java
+++ b/src/main/java/org/opensearch/knn/index/query/nativelib/NativeEngineKnnVectorQuery.java
@@ -63,11 +63,11 @@ public Weight createWeight(IndexSearcher indexSearcher, ScoreMode scoreMode, flo
         if (rescoreContext == null) {
             perLeafResults = doSearch(indexSearcher, leafReaderContexts, knnWeight, finalK);
         } else {
-            boolean isShardLevelRescoringEnabled = KNNSettings.isShardLevelRescoringEnabledForDiskBasedVector(knnQuery.getIndexName());
+            boolean isShardLevelRescoringDisabled = KNNSettings.isShardLevelRescoringDisabledForDiskBasedVector(knnQuery.getIndexName());
             int dimension = knnQuery.getQueryVector().length;
-            int firstPassK = rescoreContext.getFirstPassK(finalK, isShardLevelRescoringEnabled, dimension);
+            int firstPassK = rescoreContext.getFirstPassK(finalK, isShardLevelRescoringDisabled, dimension);
             perLeafResults = doSearch(indexSearcher, leafReaderContexts, knnWeight, firstPassK);
-            if (isShardLevelRescoringEnabled == true) {
+            if (isShardLevelRescoringDisabled == false) {
                 ResultUtil.reduceToTopK(perLeafResults, firstPassK);
             }
 
diff --git a/src/main/java/org/opensearch/knn/index/query/rescore/RescoreContext.java b/src/main/java/org/opensearch/knn/index/query/rescore/RescoreContext.java
index 09aeb75911..03c03a87fb 100644
--- a/src/main/java/org/opensearch/knn/index/query/rescore/RescoreContext.java
+++ b/src/main/java/org/opensearch/knn/index/query/rescore/RescoreContext.java
@@ -61,17 +61,17 @@ public static RescoreContext getDefault() {
      * based on the vector dimension if shard-level rescoring is disabled.
      *
      * @param finalK The final number of results to return for the entire shard.
-     * @param isShardLevelRescoringEnabled A boolean flag indicating whether shard-level rescoring is enabled.
-     *                                     If true, the dimension-based oversampling logic is bypassed.
+     * @param isShardLevelRescoringDisabled A boolean flag indicating whether shard-level rescoring is disabled.
+     *                                     If false, the dimension-based oversampling logic is bypassed.
      * @param dimension The dimension of the vector. This is used to determine the oversampling factor when
      *                  shard-level rescoring is disabled.
      * @return The number of results to return for the first pass of rescoring, adjusted by the oversample factor.
      */
-    public int getFirstPassK(int finalK, boolean isShardLevelRescoringEnabled, int dimension) {
+    public int getFirstPassK(int finalK, boolean isShardLevelRescoringDisabled, int dimension) {
         // Only apply default dimension-based oversampling logic when:
         // 1. Shard-level rescoring is disabled
         // 2. The oversample factor was not provided by the user
-        if (!isShardLevelRescoringEnabled && !userProvided) {
+        if (isShardLevelRescoringDisabled && !userProvided) {
             // Apply new dimension-based oversampling logic when shard-level rescoring is disabled
             if (dimension >= DIMENSION_THRESHOLD_1000) {
                 oversampleFactor = OVERSAMPLE_FACTOR_1000;  // No oversampling for dimensions >= 1000
diff --git a/src/test/java/org/opensearch/knn/KNNSingleNodeTestCase.java b/src/test/java/org/opensearch/knn/KNNSingleNodeTestCase.java
index 7bfce5b94a..41cd4e8a55 100644
--- a/src/test/java/org/opensearch/knn/KNNSingleNodeTestCase.java
+++ b/src/test/java/org/opensearch/knn/KNNSingleNodeTestCase.java
@@ -96,7 +96,7 @@ public void tearDown() throws Exception {
      * Create a k-NN index with default settings
      */
     protected IndexService createKNNIndex(String indexName) {
-        return createIndex(indexName, getKNNDefaultIndexSettings());
+        return createIndex(indexName, getKNNDefaultIndexSettingsBuildsGraphAlways());
     }
 
     /**
@@ -161,13 +161,6 @@ protected void createKnnNestedIndexMapping(String indexName, String fieldPath, I
         OpenSearchAssertions.assertAcked(client().admin().indices().putMapping(request).actionGet());
     }
 
-    /**
-     * Get default k-NN settings for test cases
-     */
-    protected Settings getKNNDefaultIndexSettings() {
-        return Settings.builder().put("number_of_shards", 1).put("number_of_replicas", 0).put("index.knn", true).build();
-    }
-
     /**
      * Get default k-NN settings for test cases with build graph always
      */
diff --git a/src/test/java/org/opensearch/knn/index/KNNESSettingsTestIT.java b/src/test/java/org/opensearch/knn/index/KNNESSettingsTestIT.java
index 20940f151d..b6bbb748a4 100644
--- a/src/test/java/org/opensearch/knn/index/KNNESSettingsTestIT.java
+++ b/src/test/java/org/opensearch/knn/index/KNNESSettingsTestIT.java
@@ -106,7 +106,11 @@ public void testCreateIndexWithInvalidSpaceType() throws IOException {
     }
 
     public void testUpdateIndexSetting() throws IOException {
-        Settings settings = Settings.builder().put("index.knn", true).put(KNNSettings.KNN_ALGO_PARAM_EF_SEARCH, 512).build();
+        Settings settings = Settings.builder()
+            .put("index.knn", true)
+            .put(KNNSettings.KNN_ALGO_PARAM_EF_SEARCH, 512)
+            .put(KNNSettings.INDEX_KNN_ADVANCED_APPROXIMATE_THRESHOLD, 0)
+            .build();
         createKnnIndex(INDEX_NAME, settings, createKnnIndexMapping(FIELD_NAME, 2));
         assertEquals("512", getIndexSettingByName(INDEX_NAME, KNNSettings.KNN_ALGO_PARAM_EF_SEARCH));
 
@@ -122,7 +126,7 @@ public void testUpdateIndexSetting() throws IOException {
 
     @SuppressWarnings("unchecked")
     public void testCacheRebuiltAfterUpdateIndexSettings() throws Exception {
-        createKnnIndex(INDEX_NAME, buildKNNIndexSettings(0), createKnnIndexMapping(FIELD_NAME, 2));
+        createKnnIndex(INDEX_NAME, getKNNDefaultIndexSettings(), createKnnIndexMapping(FIELD_NAME, 2));
 
         Float[] vector = { 6.0f, 6.0f };
         addKnnDoc(INDEX_NAME, "1", FIELD_NAME, vector);
diff --git a/src/test/java/org/opensearch/knn/index/KNNSettingsTests.java b/src/test/java/org/opensearch/knn/index/KNNSettingsTests.java
index c7a8e7ed83..24990dd364 100644
--- a/src/test/java/org/opensearch/knn/index/KNNSettingsTests.java
+++ b/src/test/java/org/opensearch/knn/index/KNNSettingsTests.java
@@ -159,7 +159,7 @@ public void testGetEfSearch_whenEFSearchValueSetByUser_thenReturnValue() {
     }
 
     @SneakyThrows
-    public void testShardLevelRescoringEnabled_whenNoValuesProvidedByUser_thenDefaultSettingsUsed() {
+    public void testShardLevelRescoringDisabled_whenNoValuesProvidedByUser_thenDefaultSettingsUsed() {
         Node mockNode = createMockNode(Collections.emptyMap());
         mockNode.start();
         ClusterService clusterService = mockNode.injector().getInstance(ClusterService.class);
@@ -167,7 +167,7 @@ public void testShardLevelRescoringEnabled_whenNoValuesProvidedByUser_thenDefaul
         mockNode.client().admin().indices().create(new CreateIndexRequest(INDEX_NAME)).actionGet();
         KNNSettings.state().setClusterService(clusterService);
 
-        boolean shardLevelRescoringDisabled = KNNSettings.isShardLevelRescoringEnabledForDiskBasedVector(INDEX_NAME);
+        boolean shardLevelRescoringDisabled = KNNSettings.isShardLevelRescoringDisabledForDiskBasedVector(INDEX_NAME);
         mockNode.close();
         assertFalse(shardLevelRescoringDisabled);
     }
@@ -188,7 +188,7 @@ public void testShardLevelRescoringDisabled_whenValueProvidedByUser_thenSettingA
 
         mockNode.client().admin().indices().updateSettings(new UpdateSettingsRequest(rescoringDisabledSetting, INDEX_NAME)).actionGet();
 
-        boolean shardLevelRescoringDisabled = KNNSettings.isShardLevelRescoringEnabledForDiskBasedVector(INDEX_NAME);
+        boolean shardLevelRescoringDisabled = KNNSettings.isShardLevelRescoringDisabledForDiskBasedVector(INDEX_NAME);
         mockNode.close();
         assertEquals(userDefinedRescoringDisabled, shardLevelRescoringDisabled);
     }
diff --git a/src/test/java/org/opensearch/knn/index/OpenSearchIT.java b/src/test/java/org/opensearch/knn/index/OpenSearchIT.java
index 9ca0415802..88dd908d3d 100644
--- a/src/test/java/org/opensearch/knn/index/OpenSearchIT.java
+++ b/src/test/java/org/opensearch/knn/index/OpenSearchIT.java
@@ -640,7 +640,7 @@ public void testKNNIndex_whenBuildGraphThresholdIsPresent_thenGetThresholdValue(
     public void testKNNIndex_whenBuildThresholdIsNotProvided_thenShouldNotReturnSetting() throws Exception {
         final String knnIndexMapping = createKnnIndexMapping(FIELD_NAME, KNNEngine.getMaxDimensionByEngine(KNNEngine.DEFAULT));
         final String indexName = "test-index-with-build-graph-settings";
-        createKnnIndex(indexName, knnIndexMapping);
+        createKnnIndex(indexName, getDefaultIndexSettings(), knnIndexMapping);
         final String buildVectorDataStructureThresholdSetting = getIndexSettingByName(
             indexName,
             KNNSettings.INDEX_KNN_ADVANCED_APPROXIMATE_THRESHOLD
@@ -655,7 +655,7 @@ public void testKNNIndex_whenBuildThresholdIsNotProvided_thenShouldNotReturnSett
     public void testKNNIndex_whenGetIndexSettingWithDefaultIsCalled_thenReturnDefaultBuildGraphThresholdValue() throws Exception {
         final String knnIndexMapping = createKnnIndexMapping(FIELD_NAME, KNNEngine.getMaxDimensionByEngine(KNNEngine.DEFAULT));
         final String indexName = "test-index-with-build-vector-graph-settings";
-        createKnnIndex(indexName, knnIndexMapping);
+        createKnnIndex(indexName, getDefaultIndexSettings(), knnIndexMapping);
         final String buildVectorDataStructureThresholdSetting = getIndexSettingByName(
             indexName,
             KNNSettings.INDEX_KNN_ADVANCED_APPROXIMATE_THRESHOLD,
diff --git a/src/test/java/org/opensearch/knn/index/query/nativelib/NativeEngineKNNVectorQueryTests.java b/src/test/java/org/opensearch/knn/index/query/nativelib/NativeEngineKNNVectorQueryTests.java
index 789bd10542..87c4a50148 100644
--- a/src/test/java/org/opensearch/knn/index/query/nativelib/NativeEngineKNNVectorQueryTests.java
+++ b/src/test/java/org/opensearch/knn/index/query/nativelib/NativeEngineKNNVectorQueryTests.java
@@ -183,7 +183,7 @@ public void testRescoreWhenShardLevelRescoringEnabled() {
         ) {
 
             // When shard-level re-scoring is enabled
-            mockedKnnSettings.when(() -> KNNSettings.isShardLevelRescoringEnabledForDiskBasedVector(any())).thenReturn(true);
+            mockedKnnSettings.when(() -> KNNSettings.isShardLevelRescoringDisabledForDiskBasedVector(any())).thenReturn(false);
 
             // Mock ResultUtil to return valid TopDocs
             mockedResultUtil.when(() -> ResultUtil.resultMapToTopDocs(any(), anyInt()))
@@ -265,7 +265,7 @@ public void testRescore() {
         ) {
 
             // When shard-level re-scoring is enabled
-            mockedKnnSettings.when(() -> KNNSettings.isShardLevelRescoringEnabledForDiskBasedVector(any())).thenReturn(true);
+            mockedKnnSettings.when(() -> KNNSettings.isShardLevelRescoringDisabledForDiskBasedVector(any())).thenReturn(false);
 
             mockedResultUtil.when(() -> ResultUtil.reduceToTopK(any(), anyInt())).thenAnswer(InvocationOnMock::callRealMethod);
             mockedResultUtil.when(() -> ResultUtil.resultMapToDocIds(any(), anyInt())).thenAnswer(InvocationOnMock::callRealMethod);
diff --git a/src/test/java/org/opensearch/knn/index/query/rescore/RescoreContextTests.java b/src/test/java/org/opensearch/knn/index/query/rescore/RescoreContextTests.java
index 2b309e4abd..a0a5cc5466 100644
--- a/src/test/java/org/opensearch/knn/index/query/rescore/RescoreContextTests.java
+++ b/src/test/java/org/opensearch/knn/index/query/rescore/RescoreContextTests.java
@@ -16,23 +16,23 @@ public void testGetFirstPassK() {
         float oversample = 2.6f;
         RescoreContext rescoreContext = RescoreContext.builder().oversampleFactor(oversample).userProvided(true).build();
         int finalK = 100;
-        boolean isShardLevelRescoringEnabled = true;
+        boolean isShardLevelRescoringDisabled = false;
         int dimension = 500;
 
         // Case 1: Test with standard oversample factor when shard-level rescoring is enabled
-        assertEquals(260, rescoreContext.getFirstPassK(finalK, isShardLevelRescoringEnabled, dimension));
+        assertEquals(260, rescoreContext.getFirstPassK(finalK, isShardLevelRescoringDisabled, dimension));
 
         // Case 2: Test with a very small finalK that should result in a value less than MIN_FIRST_PASS_RESULTS
         finalK = 1;
-        assertEquals(MIN_FIRST_PASS_RESULTS, rescoreContext.getFirstPassK(finalK, isShardLevelRescoringEnabled, dimension));
+        assertEquals(MIN_FIRST_PASS_RESULTS, rescoreContext.getFirstPassK(finalK, isShardLevelRescoringDisabled, dimension));
 
         // Case 3: Test with finalK = 0, should return MIN_FIRST_PASS_RESULTS
         finalK = 0;
-        assertEquals(MIN_FIRST_PASS_RESULTS, rescoreContext.getFirstPassK(finalK, isShardLevelRescoringEnabled, dimension));
+        assertEquals(MIN_FIRST_PASS_RESULTS, rescoreContext.getFirstPassK(finalK, isShardLevelRescoringDisabled, dimension));
 
         // Case 4: Test with finalK = MAX_FIRST_PASS_RESULTS, should cap at MAX_FIRST_PASS_RESULTS
         finalK = MAX_FIRST_PASS_RESULTS;
-        assertEquals(MAX_FIRST_PASS_RESULTS, rescoreContext.getFirstPassK(finalK, isShardLevelRescoringEnabled, dimension));
+        assertEquals(MAX_FIRST_PASS_RESULTS, rescoreContext.getFirstPassK(finalK, isShardLevelRescoringDisabled, dimension));
     }
 
     public void testGetFirstPassKWithDimensionBasedOversampling() {
@@ -42,44 +42,44 @@ public void testGetFirstPassKWithDimensionBasedOversampling() {
         // Case 1: Test no oversampling for dimensions >= 1000 when shard-level rescoring is disabled
         dimension = 1000;
         RescoreContext rescoreContext = RescoreContext.builder().userProvided(false).build();  // Ensuring dimension-based logic applies
-        assertEquals(100, rescoreContext.getFirstPassK(finalK, false, dimension));  // No oversampling
+        assertEquals(100, rescoreContext.getFirstPassK(finalK, true, dimension));  // No oversampling
 
         // Case 2: Test 2x oversampling for dimensions >= 768 but < 1000 when shard-level rescoring is disabled
         dimension = 800;
         rescoreContext = RescoreContext.builder().userProvided(false).build();  // Ensure previous values don't carry over
-        assertEquals(200, rescoreContext.getFirstPassK(finalK, false, dimension));  // 2x oversampling
+        assertEquals(200, rescoreContext.getFirstPassK(finalK, true, dimension));  // 2x oversampling
 
         // Case 3: Test 3x oversampling for dimensions < 768 when shard-level rescoring is disabled
         dimension = 700;
         rescoreContext = RescoreContext.builder().userProvided(false).build();  // Ensure previous values don't carry over
-        assertEquals(300, rescoreContext.getFirstPassK(finalK, false, dimension));  // 3x oversampling
+        assertEquals(300, rescoreContext.getFirstPassK(finalK, true, dimension));  // 3x oversampling
 
         // Case 4: Shard-level rescoring enabled, oversample factor should be used as provided by the user (ignore dimension)
         rescoreContext = RescoreContext.builder().oversampleFactor(5.0f).userProvided(true).build();  // Provided by user
         dimension = 500;
-        assertEquals(500, rescoreContext.getFirstPassK(finalK, true, dimension));  // User-defined oversample factor should be used
+        assertEquals(500, rescoreContext.getFirstPassK(finalK, false, dimension));  // User-defined oversample factor should be used
 
         // Case 5: Test finalK where oversampling factor results in a value less than MIN_FIRST_PASS_RESULTS
         finalK = 10;
         dimension = 700;
         rescoreContext = RescoreContext.builder().userProvided(false).build();  // Ensure dimension-based logic applies
-        assertEquals(100, rescoreContext.getFirstPassK(finalK, false, dimension));  // 3x oversampling results in 30
+        assertEquals(100, rescoreContext.getFirstPassK(finalK, true, dimension));  // 3x oversampling results in 30
     }
 
     public void testGetFirstPassKWithMinPassK() {
         float oversample = 0.5f;
         RescoreContext rescoreContext = RescoreContext.builder().oversampleFactor(oversample).userProvided(true).build();  // User provided
-        boolean isShardLevelRescoringEnabled = false;
+        boolean isShardLevelRescoringDisabled = true;
 
         // Case 1: Test where finalK * oversample is smaller than MIN_FIRST_PASS_RESULTS
         int finalK = 10;
         int dimension = 700;
-        assertEquals(MIN_FIRST_PASS_RESULTS, rescoreContext.getFirstPassK(finalK, isShardLevelRescoringEnabled, dimension));
+        assertEquals(MIN_FIRST_PASS_RESULTS, rescoreContext.getFirstPassK(finalK, isShardLevelRescoringDisabled, dimension));
 
         // Case 2: Test where finalK * oversample results in exactly MIN_FIRST_PASS_RESULTS
         finalK = 100;
         oversample = 1.0f;  // This will result in exactly 100 (MIN_FIRST_PASS_RESULTS)
         rescoreContext = RescoreContext.builder().oversampleFactor(oversample).userProvided(true).build();  // User provided
-        assertEquals(MIN_FIRST_PASS_RESULTS, rescoreContext.getFirstPassK(finalK, isShardLevelRescoringEnabled, dimension));
+        assertEquals(MIN_FIRST_PASS_RESULTS, rescoreContext.getFirstPassK(finalK, isShardLevelRescoringDisabled, dimension));
     }
 }
diff --git a/src/test/java/org/opensearch/knn/integ/ExpandNestedDocsIT.java b/src/test/java/org/opensearch/knn/integ/ExpandNestedDocsIT.java
index 38e528e955..decd74ab95 100644
--- a/src/test/java/org/opensearch/knn/integ/ExpandNestedDocsIT.java
+++ b/src/test/java/org/opensearch/knn/integ/ExpandNestedDocsIT.java
@@ -19,6 +19,7 @@
 import org.opensearch.core.xcontent.XContentBuilder;
 import org.opensearch.knn.KNNRestTestCase;
 import org.opensearch.knn.NestedKnnDocBuilder;
+import org.opensearch.knn.index.KNNSettings;
 import org.opensearch.knn.index.VectorDataType;
 import org.opensearch.knn.index.engine.KNNEngine;
 import org.opensearch.knn.index.mapper.Mode;
@@ -329,6 +330,7 @@ private void createKnnIndex(
             .put("number_of_shards", numOfShards)
             .put("number_of_replicas", 0)
             .put("index.knn", true)
+            .put(KNNSettings.INDEX_KNN_ADVANCED_APPROXIMATE_THRESHOLD, 0)
             .build();
         createKnnIndex(INDEX_NAME, settings, mapping);
     }
diff --git a/src/test/java/org/opensearch/knn/integ/KNNScriptScoringIT.java b/src/test/java/org/opensearch/knn/integ/KNNScriptScoringIT.java
index d1288c5f34..42a4f2b956 100644
--- a/src/test/java/org/opensearch/knn/integ/KNNScriptScoringIT.java
+++ b/src/test/java/org/opensearch/knn/integ/KNNScriptScoringIT.java
@@ -14,6 +14,7 @@
 import org.opensearch.knn.KNNRestTestCase;
 import org.opensearch.knn.KNNResult;
 import org.opensearch.knn.common.KNNConstants;
+import org.opensearch.knn.index.KNNSettings;
 import org.opensearch.knn.index.SpaceType;
 import org.apache.hc.core5.http.io.entity.EntityUtils;
 import org.opensearch.client.Request;
@@ -840,7 +841,11 @@ private void createIndexAndAssertScriptScore(
         /*
          * Create knn index and populate data
          */
-        Settings settings = Settings.builder().put("number_of_shards", 1).put("number_of_replicas", 0).put("index.knn", enableKnn).build();
+        Settings.Builder builder = Settings.builder().put("number_of_shards", 1).put("number_of_replicas", 0).put("index.knn", enableKnn);
+        if (enableKnn) {
+            builder.put(KNNSettings.INDEX_KNN_ADVANCED_APPROXIMATE_THRESHOLD, 0);
+        }
+        Settings settings = builder.build();
         createKnnIndex(INDEX_NAME, settings, mapper);
         try {
             final int numDocsWithField = randomIntBetween(4, 10);
diff --git a/src/test/java/org/opensearch/knn/integ/PainlessScriptScoreIT.java b/src/test/java/org/opensearch/knn/integ/PainlessScriptScoreIT.java
index 9daef76e95..4d5248a452 100644
--- a/src/test/java/org/opensearch/knn/integ/PainlessScriptScoreIT.java
+++ b/src/test/java/org/opensearch/knn/integ/PainlessScriptScoreIT.java
@@ -9,6 +9,7 @@
 import org.opensearch.common.settings.Settings;
 import org.opensearch.knn.KNNRestTestCase;
 import org.opensearch.knn.KNNResult;
+import org.opensearch.knn.index.KNNSettings;
 import org.opensearch.knn.index.engine.KNNMethodContext;
 import org.opensearch.knn.index.engine.MethodComponentContext;
 import org.opensearch.knn.index.SpaceType;
@@ -622,7 +623,11 @@ private Response buildIndexAndRunPainlessScript(
         /*
          * Create knn index and populate data
          */
-        Settings settings = Settings.builder().put("number_of_shards", 1).put("number_of_replicas", 0).put("index.knn", enableKnn).build();
+        Settings.Builder builder = Settings.builder().put("number_of_shards", 1).put("number_of_replicas", 0).put("index.knn", enableKnn);
+        if (enableKnn) {
+            builder.put(KNNSettings.INDEX_KNN_ADVANCED_APPROXIMATE_THRESHOLD, 0);
+        }
+        Settings settings = builder.build();
         createKnnIndex(INDEX_NAME, settings, mapper);
         try {
             for (Map.Entry<String, Float[]> data : documents.entrySet()) {
diff --git a/src/test/java/org/opensearch/knn/plugin/action/RestKNNStatsHandlerIT.java b/src/test/java/org/opensearch/knn/plugin/action/RestKNNStatsHandlerIT.java
index 671185abfe..e8da155892 100644
--- a/src/test/java/org/opensearch/knn/plugin/action/RestKNNStatsHandlerIT.java
+++ b/src/test/java/org/opensearch/knn/plugin/action/RestKNNStatsHandlerIT.java
@@ -24,6 +24,7 @@
 import org.opensearch.index.query.QueryBuilder;
 import org.opensearch.index.query.QueryBuilders;
 import org.opensearch.knn.KNNRestTestCase;
+import org.opensearch.knn.index.KNNSettings;
 import org.opensearch.knn.index.query.KNNQueryBuilder;
 import org.opensearch.knn.index.SpaceType;
 import org.opensearch.knn.plugin.stats.KNNStats;
@@ -292,7 +293,12 @@ public void testScriptStats_multipleShards() throws Exception {
         // Create an index with a single vector
         createKnnIndex(
             INDEX_NAME,
-            Settings.builder().put("number_of_shards", 2).put("number_of_replicas", 0).put("index.knn", true).build(),
+            Settings.builder()
+                .put("number_of_shards", 2)
+                .put("number_of_replicas", 0)
+                .put("index.knn", true)
+                .put(KNNSettings.INDEX_KNN_ADVANCED_APPROXIMATE_THRESHOLD, 0)
+                .build(),
             createKnnIndexMapping(FIELD_NAME, 2)
         );
 
diff --git a/src/test/java/org/opensearch/knn/plugin/action/RestLegacyKNNStatsHandlerIT.java b/src/test/java/org/opensearch/knn/plugin/action/RestLegacyKNNStatsHandlerIT.java
index bea93e13c7..e00d90056d 100644
--- a/src/test/java/org/opensearch/knn/plugin/action/RestLegacyKNNStatsHandlerIT.java
+++ b/src/test/java/org/opensearch/knn/plugin/action/RestLegacyKNNStatsHandlerIT.java
@@ -12,6 +12,7 @@
 package org.opensearch.knn.plugin.action;
 
 import org.opensearch.knn.KNNRestTestCase;
+import org.opensearch.knn.index.KNNSettings;
 import org.opensearch.knn.index.SpaceType;
 import org.opensearch.knn.index.query.KNNQueryBuilder;
 import org.opensearch.knn.plugin.KNNPlugin;
@@ -266,7 +267,12 @@ public void testScriptStats_multipleShards() throws Exception {
         // Create an index with a single vector
         createKnnIndex(
             INDEX_NAME,
-            Settings.builder().put("number_of_shards", 2).put("number_of_replicas", 0).put("index.knn", true).build(),
+            Settings.builder()
+                .put("number_of_shards", 2)
+                .put("number_of_replicas", 0)
+                .put("index.knn", true)
+                .put(KNNSettings.INDEX_KNN_ADVANCED_APPROXIMATE_THRESHOLD, 0)
+                .build(),
             createKnnIndexMapping(FIELD_NAME, 2)
         );
 
diff --git a/src/test/java/org/opensearch/knn/recall/RecallTestsIT.java b/src/test/java/org/opensearch/knn/recall/RecallTestsIT.java
index 3dfb674153..be2dd7b82b 100644
--- a/src/test/java/org/opensearch/knn/recall/RecallTestsIT.java
+++ b/src/test/java/org/opensearch/knn/recall/RecallTestsIT.java
@@ -46,6 +46,7 @@
 import static org.opensearch.knn.common.KNNConstants.PARAMETERS;
 import static org.opensearch.knn.common.KNNConstants.TYPE;
 import static org.opensearch.knn.common.KNNConstants.TYPE_KNN_VECTOR;
+import static org.opensearch.knn.index.KNNSettings.INDEX_KNN_ADVANCED_APPROXIMATE_THRESHOLD;
 import static org.opensearch.knn.index.KNNSettings.KNN_ALGO_PARAM_EF_SEARCH;
 import static org.opensearch.knn.index.KNNSettings.KNN_ALGO_PARAM_INDEX_THREAD_QTY;
 import static org.opensearch.knn.index.KNNSettings.KNN_MEMORY_CIRCUIT_BREAKER_ENABLED;
@@ -152,6 +153,7 @@ public void testRecall_whenNmslibHnswFP32_thenRecallAbove75percent() {
                     .put("number_of_shards", SHARD_COUNT)
                     .put("number_of_replicas", REPLICA_COUNT)
                     .put("index.knn", true)
+                    .put(INDEX_KNN_ADVANCED_APPROXIMATE_THRESHOLD, 0)
                     .put(KNN_ALGO_PARAM_EF_SEARCH, HNSW_EF_SEARCH)
                     .build(),
                 builder.toString()
@@ -531,6 +533,7 @@ private Settings getSettings() {
             .put("number_of_shards", SHARD_COUNT)
             .put("number_of_replicas", REPLICA_COUNT)
             .put("index.knn", true)
+            .put(INDEX_KNN_ADVANCED_APPROXIMATE_THRESHOLD, 0)
             .build();
     }
 }
diff --git a/src/testFixtures/java/org/opensearch/knn/KNNRestTestCase.java b/src/testFixtures/java/org/opensearch/knn/KNNRestTestCase.java
index a5b4b06923..896674a18c 100644
--- a/src/testFixtures/java/org/opensearch/knn/KNNRestTestCase.java
+++ b/src/testFixtures/java/org/opensearch/knn/KNNRestTestCase.java
@@ -797,7 +797,14 @@ protected void updateClusterSettings(String settingKey, Object value) throws Exc
      * Return default index settings for index creation
      */
     protected Settings getKNNDefaultIndexSettings() {
-        return Settings.builder().put("number_of_shards", 1).put("number_of_replicas", 0).put("index.knn", true).build();
+        return buildKNNIndexSettings(0);
+    }
+
+    /**
+     * Return default index settings for index creation
+     */
+    protected Settings getDefaultIndexSettings() {
+        return Settings.builder().put("number_of_shards", 1).put("number_of_replicas", 0).put(KNN_INDEX, true).build();
     }
 
     protected Settings getKNNSegmentReplicatedIndexSettings() {