diff --git a/internal/indexnode/task.go b/internal/indexnode/task.go
index 3486ccfc98..8686036791 100644
--- a/internal/indexnode/task.go
+++ b/internal/indexnode/task.go
@@ -399,7 +399,7 @@ func (it *indexBuildTask) BuildDiskAnnIndex(ctx context.Context) error {
 
 	it.tr.Record("build index done")
 
-	indexBlobs, err := it.index.SerializeDiskIndex()
+	fileInfos, err := it.index.GetIndexFileInfo()
 	if err != nil {
 		log.Ctx(ctx).Error("IndexNode index Serialize failed", zap.Error(err))
 		return err
@@ -408,8 +408,12 @@ func (it *indexBuildTask) BuildDiskAnnIndex(ctx context.Context) error {
 
 	// use serialized size before encoding
 	it.serializedSize = 0
-	for _, blob := range indexBlobs {
-		it.serializedSize += uint64(blob.Size)
+	for _, info := range fileInfos {
+		it.serializedSize += uint64(info.FileSize)
+		it.indexBlobs = append(it.indexBlobs, &storage.Blob{
+			Key:  info.FileName,
+			Size: info.FileSize,
+		})
 	}
 
 	// early release index for gc, and we can ensure that Delete is idempotent.
@@ -419,7 +423,6 @@ func (it *indexBuildTask) BuildDiskAnnIndex(ctx context.Context) error {
 
 	encodeIndexFileDur := it.tr.Record("index codec serialize done")
 	metrics.IndexNodeEncodeIndexFileLatency.WithLabelValues(strconv.FormatInt(Params.IndexNodeCfg.GetNodeID(), 10)).Observe(float64(encodeIndexFileDur.Milliseconds()))
-	it.indexBlobs = indexBlobs
 	return nil
 }
 
diff --git a/internal/util/indexcgowrapper/index.go b/internal/util/indexcgowrapper/index.go
index 1a1b693401..dd8bada457 100644
--- a/internal/util/indexcgowrapper/index.go
+++ b/internal/util/indexcgowrapper/index.go
@@ -25,10 +25,15 @@ import (
 
 type Blob = storage.Blob
 
+type IndexFileInfo struct {
+	FileName string
+	FileSize int64
+}
+
 type CodecIndex interface {
 	Build(*Dataset) error
 	Serialize() ([]*Blob, error)
-	SerializeDiskIndex() ([]*Blob, error)
+	GetIndexFileInfo() ([]*IndexFileInfo, error)
 	Load([]*Blob) error
 	Delete() error
 	CleanLocalData() error
@@ -233,7 +238,7 @@ func (index *CgoIndex) Serialize() ([]*Blob, error) {
 	return ret, nil
 }
 
-func (index *CgoIndex) SerializeDiskIndex() ([]*Blob, error) {
+func (index *CgoIndex) GetIndexFileInfo() ([]*IndexFileInfo, error) {
 	var cBinarySet C.CBinarySet
 
 	status := C.SerializeIndexToBinarySet(index.indexPtr, &cBinarySet)
@@ -250,17 +255,17 @@ func (index *CgoIndex) SerializeDiskIndex() ([]*Blob, error) {
 	if err != nil {
 		return nil, err
 	}
-	ret := make([]*Blob, 0)
+	ret := make([]*IndexFileInfo, 0)
 	for _, key := range keys {
 		size, err := GetBinarySetSize(cBinarySet, key)
 		if err != nil {
 			return nil, err
 		}
-		blob := &Blob{
-			Key:  key,
-			Size: size,
+		info := &IndexFileInfo{
+			FileName: key,
+			FileSize: size,
 		}
-		ret = append(ret, blob)
+		ret = append(ret, info)
 	}
 
 	return ret, nil