diff --git a/src/client/src/tscSql.c b/src/client/src/tscSql.c
index d4dbec72236e1c7d321e4be139295cd6daad0bf3..568b45f5ddb802524567b1930162855ad5e9cba1 100644
--- a/src/client/src/tscSql.c
+++ b/src/client/src/tscSql.c
@@ -742,15 +742,15 @@ static void tscKillSTableQuery(SSqlObj *pSql) {
     }
 
     tscAsyncResultOnError(pSubObj);
-    // taosRelekaseRef(tscObjRef, pSubObj->self);
   }
 
-  pthread_mutex_unlock(&pSql->subState.mutex); }
 
   if (pSql->subState.numOfSub <= 0) {
     tscAsyncResultOnError(pSql);
   }
 
+  pthread_mutex_unlock(&pSql->subState.mutex); }
+
   tscUnlockByThread(&pSql->squeryLock);
 
   tscDebug("0x%"PRIx64" super table query cancelled", pSql->self);
diff --git a/src/client/src/tscSubquery.c b/src/client/src/tscSubquery.c
index ae2a3f33f9b7afb3b1950c361a664051201dc4ef..28daa227a05d80d5c0986d500abcaf917eb66efe 100644
--- a/src/client/src/tscSubquery.c
+++ b/src/client/src/tscSubquery.c
@@ -535,26 +535,13 @@ static SArray* buildVgroupTableByResult(SQueryInfo* pQueryInfo, SArray* pVgroupT
  * launch secondary stage query to fetch the result that contains timestamp in set
  */
 static int32_t tscLaunchRealSubqueries(SSqlObj* pSql) {
-  int32_t         numOfSub = 0;
   SJoinSupporter* pSupporter = NULL;
   bool success = true;
   uint32_t stateVersion = 0;
 
   { pthread_mutex_lock(&pSql->subState.mutex);
 
-  //If the columns are not involved in the final select clause, the corresponding query will not be issued.
-  for (int32_t i = 0; i < pSql->subState.numOfSub; ++i) {
-    pSupporter = pSql->pSubs[i]->param;
-    if (taosArrayGetSize(pSupporter->exprList) > 0) {
-      ++numOfSub;
-    }
-  }
-
-  assert(numOfSub > 0);
-
   // scan all subquery, if one sub query has only ts, ignore it
-  tscDebug("0x%"PRIx64" start to launch secondary subqueries, %d out of %d needs to query", pSql->self, numOfSub, pSql->subState.numOfSub);
-
   for (int32_t i = 0; i < pSql->subState.numOfSub; ++i) {
     SSqlObj *pPrevSub = pSql->pSubs[i];
     if (!pPrevSub) continue;
@@ -589,6 +576,7 @@ static int32_t tscLaunchRealSubqueries(SSqlObj* pSql) {
 
     tscClearSubqueryInfo(&pNew->cmd);
     pSql->pSubs[i] = pNew;
+    pSql->subState.version ++;
 
     SQueryInfo *pQueryInfo = tscGetQueryInfo(&pNew->cmd);
     pQueryInfo->tsBuf = pTsBuf;  // transfer the ownership of timestamp comp-z data to the new created object
@@ -1080,6 +1068,11 @@ static int32_t getIntersectionOfTableTuple(SQueryInfo* pQueryInfo, SSqlObj* pPar
   tscDebug("0x%"PRIx64" all subquery retrieve <tid, tags> complete, do tags match", pParentSql->self);
 
   for (int32_t i = 0; i < joinNum; i++) {
+    if (!pParentSql->pSubs[i]) {
+        tscError("0x%"PRIx64"some of subquery objs not exist. numOfSub:%d, i: %d", pParentSql->self, pParentSql->subState.numOfSub, i);
+        code = TSDB_CODE_FAILED;
+        break;
+    }
     SJoinSupporter* p = pParentSql->pSubs[i]->param;
 
     setTidTagType(p, pColSchema->type);
@@ -2132,6 +2125,7 @@ int32_t tscCreateJoinSubquery(SSqlObj *pSql, int16_t tableIndex, SJoinSupporter
   }
 
   pSql->pSubs[tableIndex] = pNew;
+  pSql->subState.version ++;
 
   if (QUERY_IS_JOIN_QUERY(pQueryInfo->type)) {
     addGroupInfoForSubquery(pSql, pNew, 0, tableIndex);
@@ -2261,7 +2255,9 @@ void tscHandleMasterJoinQuery(SSqlObj* pSql) {
   int32_t code = TSDB_CODE_SUCCESS;
 
   code = doReInitSubState(pSql, pQueryInfo->numOfTables);
-  assert (code == TSDB_CODE_SUCCESS && "Out of memory");
+  if (code != TSDB_CODE_SUCCESS) {
+    goto _error;
+  }
 
   uint32_t stateVersion = 0;
   int errflag = 0;
@@ -2269,6 +2265,13 @@ void tscHandleMasterJoinQuery(SSqlObj* pSql) {
   { pthread_mutex_lock(&pSql->subState.mutex);
 
   for (int32_t i = 0; i < pSql->subState.numOfSub; ++i) {
+    if (pSql->pSubs[i] != NULL) {
+       tscError("0x%"PRIx64"some of subquery objs already set. numOfSub:%d, i: %d", pSql->self, pSql->subState.numOfSub, i);
+       code = TSDB_CODE_FAILED;
+       errflag = 1;
+       break;
+    }
+
     SJoinSupporter *pSupporter = tscCreateJoinSupporter(pSql, i);
     if (pSupporter == NULL) {  // failed to create support struct, abort current query
       tscError("0x%"PRIx64" tableIndex:%d, failed to allocate join support object, abort further query", pSql->self, i);
@@ -2284,6 +2287,7 @@ void tscHandleMasterJoinQuery(SSqlObj* pSql) {
       break;
     }
 
+    // pSub has been recreated.
     SSqlObj* pSub = pSql->pSubs[i];
     STableMetaInfo* pTableMetaInfo = tscGetTableMetaInfoFromCmd(&pSub->cmd, 0);
     if (UTIL_TABLE_IS_SUPER_TABLE(pTableMetaInfo) && (pTableMetaInfo->vgroupList->numOfVgroups == 0)) {
@@ -3446,6 +3450,13 @@ static bool needRetryInsert(SSqlObj* pParentObj) {
   { pthread_mutex_lock(&pParentObj->subState.mutex);
 
   for (int32_t i = 0; i < pParentObj->subState.numOfSub; ++i) {
+    if (!pParentObj->pSubs[i]) {
+        tscError("0x%"PRIx64"some of subquery objs not exist. numOfSub:%d, i: %d", pParentObj->self, pParentObj->subState.numOfSub, i);
+        pParentObj->res.code = TSDB_CODE_FAILED;
+        ret = false;
+        break;
+    }
+
     int32_t code = pParentObj->pSubs[i]->res.code;
     if (code == TSDB_CODE_SUCCESS) {
       continue;
@@ -3655,8 +3666,16 @@ int32_t tscHandleMultivnodeInsert(SSqlObj *pSql) {
   tscDebug("0x%"PRIx64" submit data to %d vnode(s)", pSql->self, pSql->subState.numOfSub);
 
   while(numOfSub < pSql->subState.numOfSub) {
+    if (pSql->pSubs[numOfSub] != NULL) {
+        tscError("0x%"PRIx64"some of subquery objs already set. numOfSub:%d, i: %d", pSql->self, pSql->subState.numOfSub, numOfSub);
+        code = TSDB_CODE_FAILED;
+        errflag = 1;
+        break;
+    }
+
     SInsertSupporter* pSupporter = calloc(1, sizeof(SInsertSupporter));
     if (pSupporter == NULL) {
+      code = TSDB_CODE_TSC_OUT_OF_MEMORY;
       errflag = 1;
       break;
     }
@@ -3667,6 +3686,7 @@ int32_t tscHandleMultivnodeInsert(SSqlObj *pSql) {
     SSqlObj *pNew = createSimpleSubObj(pSql, multiVnodeInsertFinalize, pSupporter, TSDB_SQL_INSERT);
     if (pNew == NULL) {
       tscError("0x%"PRIx64" failed to malloc buffer for subObj, orderOfSub:%d, reason:%s", pSql->self, numOfSub, strerror(errno));
+      code = TSDB_CODE_TSC_OUT_OF_MEMORY;
       errflag = 1;
       break;
     }
@@ -3678,10 +3698,11 @@ int32_t tscHandleMultivnodeInsert(SSqlObj *pSql) {
     pNew->fetchFp = pNew->fp;
 
     pSql->pSubs[numOfSub] = pNew;
+    pSql->subState.version ++;
 
     STableDataBlocks* pTableDataBlock = taosArrayGetP(pCmd->insertParam.pDataBlocks, numOfSub);
-    pRes->code = tscCopyDataBlockToPayload(pNew, pTableDataBlock);
-    if (pRes->code == TSDB_CODE_SUCCESS) {
+    code = tscCopyDataBlockToPayload(pNew, pTableDataBlock);
+    if (code == TSDB_CODE_SUCCESS) {
       tscDebug("0x%"PRIx64" sub:%p create subObj success. orderOfSub:%d", pSql->self, pNew, numOfSub);
       numOfSub++;
     } else {
@@ -3694,7 +3715,7 @@ int32_t tscHandleMultivnodeInsert(SSqlObj *pSql) {
 
   if (numOfSub < pSql->subState.numOfSub) {
     tscError("0x%"PRIx64" failed to prepare subObj structure and launch sub-insertion", pSql->self);
-    pRes->code = TSDB_CODE_TSC_OUT_OF_MEMORY;
+    pRes->code = code;
     errflag = 1;
   }
 
@@ -3725,7 +3746,7 @@ int32_t tscHandleMultivnodeInsert(SSqlObj *pSql) {
   return TSDB_CODE_SUCCESS;
 
 _error:
-  return TSDB_CODE_TSC_OUT_OF_MEMORY;
+  return pRes->code;
 }
 
 static char* getResultBlockPosition(SSqlCmd* pCmd, SSqlRes* pRes, int32_t columnIndex, int16_t* bytes) {
diff --git a/src/client/src/tscUtil.c b/src/client/src/tscUtil.c
index 6a33952a2f484ae049f7340a20f5d51a764e1a05..9944c22e89a558a64b702a34208be9bdcfa00fcc 100644
--- a/src/client/src/tscUtil.c
+++ b/src/client/src/tscUtil.c
@@ -4247,6 +4247,13 @@ void executeQuery(SSqlObj* pSql, SQueryInfo* pQueryInfo) {
     { pthread_mutex_lock(&pSql->subState.mutex);
 
     for(int32_t i = 0; i < pSql->subState.numOfSub; ++i) {
+      if (pSql->pSubs[i] != NULL) {
+        tscError("0x%"PRIx64"some of subquery objs already set. numOfSub:%d, i: %d", pSql->self, pSql->subState.numOfSub, i);
+        code = TSDB_CODE_FAILED;
+        errflag = 1;
+        break;
+      }
+
       SQueryInfo* pSub = taosArrayGetP(pQueryInfo->pUpstream, i);
 
       pSql->cmd.active = pSub;
@@ -4283,6 +4290,7 @@ void executeQuery(SSqlObj* pSql, SQueryInfo* pQueryInfo) {
       registerSqlObj(pNew);
 
       pSql->pSubs[i] = pNew;
+      pSql->subState.version ++;
 
       SSqlCmd* pCmd = &pNew->cmd;
       pCmd->command = TSDB_SQL_SELECT;