diff --git a/source/libs/index/inc/index_fst_node.h b/source/libs/index/inc/index_fst_node.h
index 09dcd223b1..631c7026c5 100644
--- a/source/libs/index/inc/index_fst_node.h
+++ b/source/libs/index/inc/index_fst_node.h
@@ -33,6 +33,8 @@ typedef struct FstBuilderNode {
 
 FstBuilderNode *fstBuilderNodeDefault();
 
+FstBuilderNode *fstBuilderNodeClone(FstBuilderNode *src);
+
 void fstBuilderNodeCloneFrom(FstBuilderNode *dst, FstBuilderNode *src);
 
 #endif
diff --git a/source/libs/index/inc/index_fst_registry.h b/source/libs/index/inc/index_fst_registry.h
index d54d73683f..f19bb750c2 100644
--- a/source/libs/index/inc/index_fst_registry.h
+++ b/source/libs/index/inc/index_fst_registry.h
@@ -54,5 +54,4 @@ FstRegistry* fstRegistryCreate(uint64_t tableSize, uint64_t mruSize);
 
 FstRegistryEntry* fstRegistryGetEntry(FstRegistry *registry, FstBuilderNode *bNode);
 
-uint64_t fstRegistryHash(FstRegistry *registry, FstBuilderNode *node);
 #endif
diff --git a/source/libs/index/src/index_fst_node.c b/source/libs/index/src/index_fst_node.c
index 1511781719..23af4a4a4b 100644
--- a/source/libs/index/src/index_fst_node.c
+++ b/source/libs/index/src/index_fst_node.c
@@ -22,6 +22,26 @@ FstBuilderNode *fstBuilderNodeDefault() {
   return bn;
 }
 
+FstBuilderNode *fstBuilderNodeClone(FstBuilderNode *src) {
+  FstBuilderNode *node = malloc(sizeof(FstBuilderNode));  
+  if (node == NULL) { return NULL; }
+
+      
+  size_t sz = taosArrayGetSize(src->trans);
+  SArray *trans = taosArrayInit(sz, sizeof(FstTransition));
+
+  for (size_t i = 0; i < sz; i++) {
+    FstTransition *tran = taosArrayGet(src->trans, i);
+    FstTransition t = *tran;
+    taosArrayPush(trans, &t);   
+  }
+
+  node->trans = trans; 
+  node->isFinal = src->isFinal;
+  node->finalOutput = src->finalOutput;
+  return node;
+
+}
 // not destroy src, User's bussiness  
 void fstBuilderNodeCloneFrom(FstBuilderNode *dst, FstBuilderNode *src) {
   if (dst == NULL || src == NULL) { return; }