diff --git a/src/main/java/org/opensearch/knn/index/codec/KNN990Codec/NativeEngines990KnnVectorsWriter.java b/src/main/java/org/opensearch/knn/index/codec/KNN990Codec/NativeEngines990KnnVectorsWriter.java
index 2c110fb79..1d3ff368a 100644
--- a/src/main/java/org/opensearch/knn/index/codec/KNN990Codec/NativeEngines990KnnVectorsWriter.java
+++ b/src/main/java/org/opensearch/knn/index/codec/KNN990Codec/NativeEngines990KnnVectorsWriter.java
@@ -24,11 +24,13 @@
 import org.apache.lucene.index.Sorter;
 import org.apache.lucene.util.IOUtils;
 import org.apache.lucene.util.RamUsageEstimator;
+import org.opensearch.common.StopWatch;
 import org.opensearch.knn.index.quantizationservice.QuantizationService;
 import org.opensearch.knn.index.VectorDataType;
 import org.opensearch.knn.index.codec.nativeindex.NativeIndexWriter;
 import org.opensearch.knn.index.vectorvalues.KNNVectorValues;
 import org.opensearch.knn.index.vectorvalues.KNNVectorValuesFactory;
+import org.opensearch.knn.plugin.stats.KNNGraphValue;
 import org.opensearch.knn.quantization.models.quantizationParams.QuantizationParams;
 import org.opensearch.knn.quantization.models.quantizationState.QuantizationState;
 
@@ -45,6 +47,10 @@
 @RequiredArgsConstructor
 public class NativeEngines990KnnVectorsWriter extends KnnVectorsWriter {
     private static final long SHALLOW_SIZE = RamUsageEstimator.shallowSizeOfInstance(NativeEngines990KnnVectorsWriter.class);
+
+    private static final String FLUSH_OPERATION = "flush";
+    private static final String MERGE_OPERATION = "merge";
+
     private final SegmentWriteState segmentWriteState;
     private final FlatVectorsWriter flatVectorsWriter;
     private final List<NativeEngineFieldVectorsWriter<?>> fields = new ArrayList<>();
@@ -78,7 +84,9 @@ public void flush(int maxDoc, final Sorter.DocMap sortMap) throws IOException {
                 field.getFieldInfo(),
                 (vectorDataType, fieldInfo, fieldVectorsWriter) -> getKNNVectorValues(vectorDataType, fieldVectorsWriter),
                 NativeIndexWriter::flushIndex,
-                field
+                field,
+                KNNGraphValue.REFRESH_TOTAL_TIME_IN_MILLIS,
+                FLUSH_OPERATION
             );
         }
     }
@@ -88,7 +96,14 @@ public void mergeOneField(final FieldInfo fieldInfo, final MergeState mergeState
         // This will ensure that we are merging the FlatIndex during force merge.
         flatVectorsWriter.mergeOneField(fieldInfo, mergeState);
         // For merge, pick values from flat vector and reindex again. This will use the flush operation to create graphs
-        trainAndIndex(fieldInfo, this::getKNNVectorValuesForMerge, NativeIndexWriter::mergeIndex, mergeState);
+        trainAndIndex(
+            fieldInfo,
+            this::getKNNVectorValuesForMerge,
+            NativeIndexWriter::mergeIndex,
+            mergeState,
+            KNNGraphValue.MERGE_TOTAL_TIME_IN_MILLIS,
+            MERGE_OPERATION
+        );
 
     }
 
@@ -214,7 +229,9 @@ private <T, C> void trainAndIndex(
         final FieldInfo fieldInfo,
         final VectorValuesRetriever<VectorDataType, FieldInfo, C, KNNVectorValues<T>> vectorValuesRetriever,
         final IndexOperation<T> indexOperation,
-        final C VectorProcessingContext
+        final C VectorProcessingContext,
+        final KNNGraphValue graphBuildTime,
+        final String operationName
     ) throws IOException {
         final VectorDataType vectorDataType = extractVectorDataType(fieldInfo);
         KNNVectorValues<T> knnVectorValues = vectorValuesRetriever.apply(vectorDataType, fieldInfo, VectorProcessingContext);
@@ -228,6 +245,12 @@ private <T, C> void trainAndIndex(
             : NativeIndexWriter.getWriter(fieldInfo, segmentWriteState);
 
         knnVectorValues = vectorValuesRetriever.apply(vectorDataType, fieldInfo, VectorProcessingContext);
+
+        StopWatch stopWatch = new StopWatch();
+        stopWatch.start();
         indexOperation.buildAndWrite(writer, knnVectorValues);
+        long time_in_millis = stopWatch.totalTime().millis();
+        graphBuildTime.incrementBy(time_in_millis);
+        log.warn("Graph build took " + time_in_millis + " ms for " + operationName);
     }
 }
diff --git a/src/test/java/org/opensearch/knn/index/codec/KNN990Codec/NativeEngines990KnnVectorsFormatTests.java b/src/test/java/org/opensearch/knn/index/codec/KNN990Codec/NativeEngines990KnnVectorsFormatTests.java
index 85b5d07e6..7bf17ec54 100644
--- a/src/test/java/org/opensearch/knn/index/codec/KNN990Codec/NativeEngines990KnnVectorsFormatTests.java
+++ b/src/test/java/org/opensearch/knn/index/codec/KNN990Codec/NativeEngines990KnnVectorsFormatTests.java
@@ -51,6 +51,7 @@
 import org.opensearch.knn.index.engine.qframe.QuantizationConfigParser;
 import org.opensearch.knn.index.mapper.KNNVectorFieldMapper;
 import org.opensearch.knn.index.engine.KNNEngine;
+import org.opensearch.knn.plugin.stats.KNNGraphValue;
 import org.opensearch.knn.quantization.enums.ScalarQuantizationType;
 
 import java.io.IOException;
@@ -135,6 +136,8 @@ public void testNativeEngineVectorFormat_whenMultipleVectorFieldIndexed_thenSucc
         indexWriter.commit();
         indexWriter.close();
 
+        assertNotEquals(0L, (long) KNNGraphValue.REFRESH_TOTAL_TIME_IN_MILLIS.getValue());
+
         // Validate to see if correct values are returned, assumption here is only 1 segment is getting created
         IndexSearcher searcher = new IndexSearcher(indexReader);
         final LeafReader leafReader = searcher.getLeafContexts().get(0).reader();
@@ -204,6 +207,8 @@ public void testNativeEngineVectorFormat_whenBinaryQuantizationApplied_thenSucce
         indexWriter.flush();
         indexWriter.commit();
         indexWriter.close();
+        assertNotEquals(0L, (long) KNNGraphValue.REFRESH_TOTAL_TIME_IN_MILLIS.getValue());
+
         IndexSearcher searcher = new IndexSearcher(indexReader);
         final LeafReader leafReader = searcher.getLeafContexts().get(0).reader();
         SegmentReader segmentReader = Lucene.segmentReader(leafReader);