diff --git a/src/client/src/tscSubquery.c b/src/client/src/tscSubquery.c
index 03c3c77459d70174ef0debd94be71f4d1ef95d84..6c6284b4a6dca4e3fa7fc4337e6ea5fa0089a09c 100644
--- a/src/client/src/tscSubquery.c
+++ b/src/client/src/tscSubquery.c
@@ -1914,6 +1914,7 @@ int32_t tscHandleMultivnodeInsert(SSqlObj *pSql) {
   pSql->pSubs[0] = pSql;  // the first sub insert points back to itself
   tscTrace("%p sub:%p create subObj success. orderOfSub:%d", pSql, pSql, 0);
 
+  int32_t numOfSub = 1;
   int32_t code = tscCopyDataBlockToPayload(pSql, pDataBlocks->pData[0]);
   if (code != TSDB_CODE_SUCCESS) {
     tscTrace("%p prepare submit data block failed in async insertion, vnodeIdx:%d, total:%d, code:%d", pSql, 0,
@@ -1921,15 +1922,14 @@ int32_t tscHandleMultivnodeInsert(SSqlObj *pSql) {
     goto _error;
   }
 
-  int32_t i = 1;
-  for (; i < pSql->numOfSubs; ++i) {
+  for (; numOfSub < pSql->numOfSubs; ++numOfSub) {
     SInsertSupporter* pSupporter1 = calloc(1, sizeof(SInsertSupporter));
     pSupporter1->pSql = pSql;
     pSupporter1->pState = pState;
     
     SSqlObj *pNew = createSubqueryObj(pSql, 0, multiVnodeInsertFinalize, pSupporter1, TSDB_SQL_INSERT, NULL);
     if (pNew == NULL) {
-      tscError("%p failed to malloc buffer for subObj, orderOfSub:%d, reason:%s", pSql, i, strerror(errno));
+      tscError("%p failed to malloc buffer for subObj, orderOfSub:%d, reason:%s", pSql, numOfSub, strerror(errno));
       goto _error;
     }
   
@@ -1938,26 +1938,25 @@ int32_t tscHandleMultivnodeInsert(SSqlObj *pSql) {
      * the callback function (multiVnodeInsertFinalize) correctly.
      */
     pNew->fetchFp = pNew->fp;
-    pSql->pSubs[i] = pNew;
+    pSql->pSubs[numOfSub] = pNew;
 
-    code = tscCopyDataBlockToPayload(pNew, pDataBlocks->pData[i]);
+    code = tscCopyDataBlockToPayload(pNew, pDataBlocks->pData[numOfSub]);
     if (code != TSDB_CODE_SUCCESS) {
-      tscTrace("%p prepare submit data block failed in async insertion, vnodeIdx:%d, total:%d, code:%d", pSql, i,
+      tscTrace("%p prepare submit data block failed in async insertion, vnodeIdx:%d, total:%d, code:%d", pSql, numOfSub,
                pDataBlocks->nSize, code);
       goto _error;
     } else {
-      tscTrace("%p sub:%p create subObj success. orderOfSub:%d", pSql, pNew, i);
+      tscTrace("%p sub:%p create subObj success. orderOfSub:%d", pSql, pNew, numOfSub);
     }
   }
   
-  if (i < pSql->numOfSubs) {
+  if (numOfSub < pSql->numOfSubs) {
     tscError("%p failed to prepare subObj structure and launch sub-insertion", pSql);
     pRes->code = TSDB_CODE_TSC_OUT_OF_MEMORY;
     return pRes->code;  // free all allocated resource
   }
 
   // use the local variable
-  int32_t numOfSub = pSql->numOfSubs;
   for (int32_t j = 0; j < numOfSub; ++j) {
     SSqlObj *pSub = pSql->pSubs[j];
     tscTrace("%p sub:%p launch sub insert, orderOfSub:%d", pSql, pSub, j);
@@ -1969,11 +1968,12 @@ int32_t tscHandleMultivnodeInsert(SSqlObj *pSql) {
   _error:
   // restore the udf fp
   pSql->fp = pSql->fetchFp;
+  pSql->pSubs[0] = NULL;
 
   tfree(pState);
   tfree(pSql->param);
 
-  for(int32_t j = 1; j < i; ++j) {
+  for(int32_t j = 1; j < numOfSub; ++j) {
     tfree(pSql->pSubs[j]->param);
     taos_free_result(pSql->pSubs[j]);
   }