diff --git a/src/client/inc/tscSubquery.h b/src/client/inc/tscSubquery.h
index d3996ccf7fe85a6405addfcbef023aa2ae6bf08b..43c9b009bfdc537b033b7cffbe00bb673c627847 100644
--- a/src/client/inc/tscSubquery.h
+++ b/src/client/inc/tscSubquery.h
@@ -43,6 +43,11 @@ TAOS_ROW doSetResultRowData(SSqlObj *pSql);
 
 char *getArithmeticInputSrc(void *param, const char *name, int32_t colId);
 
+void tscLockByThread(int64_t *lockedBy);
+
+void tscUnlockByThread(int64_t *lockedBy);
+
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/src/client/inc/tsclient.h b/src/client/inc/tsclient.h
index 25a299d0988144980dded10b170cbe7b7c662b04..ecef3792fad59c3530c36c3912e2a4730565c4b3 100644
--- a/src/client/inc/tsclient.h
+++ b/src/client/inc/tsclient.h
@@ -347,6 +347,11 @@ typedef struct SSqlObj {
   SSubqueryState   subState;
   struct SSqlObj **pSubs;
 
+  int64_t          metaRid;
+  int64_t          svgroupRid;
+
+  int64_t          squeryLock;
+
   struct SSqlObj  *prev, *next;
   int64_t          self;
 } SSqlObj;
diff --git a/src/client/src/tscAsync.c b/src/client/src/tscAsync.c
index 41e935441fd11428420efc98dc53616b7d2317dc..91ac52adbbe629cdd0836e24a887fba14c647142 100644
--- a/src/client/src/tscAsync.c
+++ b/src/client/src/tscAsync.c
@@ -402,8 +402,10 @@ void tscAsyncResultOnError(SSqlObj *pSql) {
 int tscSendMsgToServer(SSqlObj *pSql);
 
 void tscTableMetaCallBack(void *param, TAOS_RES *res, int code) {
-  SSqlObj *pSql = (SSqlObj *)param;
-  if (pSql == NULL || pSql->signature != pSql) return;
+  SSqlObj* pSql = (SSqlObj*)taosAcquireRef(tscObjRef, (int64_t)param);
+  if (pSql == NULL) return;
+
+  assert(pSql->signature == pSql && (int64_t)param == pSql->self);
 
   SSqlCmd *pCmd = &pSql->cmd;
   SSqlRes *pRes = &pSql->res;
@@ -428,7 +430,8 @@ void tscTableMetaCallBack(void *param, TAOS_RES *res, int code) {
       code = tscGetTableMeta(pSql, pTableMetaInfo);
       assert(code == TSDB_CODE_TSC_ACTION_IN_PROGRESS || code == TSDB_CODE_SUCCESS);
 
-      if (code == TSDB_CODE_TSC_ACTION_IN_PROGRESS) {
+      if (code == TSDB_CODE_TSC_ACTION_IN_PROGRESS) {        
+        taosReleaseRef(tscObjRef, pSql->self);
         return;
       }
 
@@ -436,6 +439,7 @@ void tscTableMetaCallBack(void *param, TAOS_RES *res, int code) {
 
       // tscProcessSql can add error into async res
       tscProcessSql(pSql);
+      taosReleaseRef(tscObjRef, pSql->self);
       return;
     } else {  // continue to process normal async query
       if (pCmd->parseFinished) {
@@ -446,6 +450,7 @@ void tscTableMetaCallBack(void *param, TAOS_RES *res, int code) {
 
         assert(code == TSDB_CODE_TSC_ACTION_IN_PROGRESS || code == TSDB_CODE_SUCCESS);
         if (code == TSDB_CODE_TSC_ACTION_IN_PROGRESS) {
+          taosReleaseRef(tscObjRef, pSql->self);
           return;
         }
 
@@ -458,6 +463,7 @@ void tscTableMetaCallBack(void *param, TAOS_RES *res, int code) {
 
           code = tsParseSql(pSql, true);
           if (code == TSDB_CODE_TSC_ACTION_IN_PROGRESS) {
+            taosReleaseRef(tscObjRef, pSql->self);
             return;
           } else if (code != TSDB_CODE_SUCCESS) {
             goto _error;
@@ -468,12 +474,14 @@ void tscTableMetaCallBack(void *param, TAOS_RES *res, int code) {
           tscProcessSql(pSql);
         }
 
+        taosReleaseRef(tscObjRef, pSql->self);
         return;
       } else {
         tscDebug("%p continue parse sql after get table meta", pSql);
 
         code = tsParseSql(pSql, false);
         if (code == TSDB_CODE_TSC_ACTION_IN_PROGRESS) {
+          taosReleaseRef(tscObjRef, pSql->self);
           return;
         } else if (code != TSDB_CODE_SUCCESS) {
           goto _error;
@@ -483,12 +491,14 @@ void tscTableMetaCallBack(void *param, TAOS_RES *res, int code) {
           STableMetaInfo* pTableMetaInfo = tscGetTableMetaInfoFromCmd(pCmd, pCmd->clauseIndex, 0);
           code = tscGetTableMeta(pSql, pTableMetaInfo);
           if (code == TSDB_CODE_TSC_ACTION_IN_PROGRESS) {
+            taosReleaseRef(tscObjRef, pSql->self);
             return;
           } else {
             assert(code == TSDB_CODE_SUCCESS);      
           }
 
           (*pSql->fp)(pSql->param, pSql, code);
+          taosReleaseRef(tscObjRef, pSql->self);
           return;
         }
 
@@ -501,6 +511,7 @@ void tscTableMetaCallBack(void *param, TAOS_RES *res, int code) {
 
     code = tscGetTableMeta(pSql, pTableMetaInfo);
     if (code == TSDB_CODE_TSC_ACTION_IN_PROGRESS) {
+      taosReleaseRef(tscObjRef, pSql->self);
       return;
     } else if (code != TSDB_CODE_SUCCESS) {
       goto _error;
@@ -509,6 +520,7 @@ void tscTableMetaCallBack(void *param, TAOS_RES *res, int code) {
     if (UTIL_TABLE_IS_SUPER_TABLE(pTableMetaInfo)) {
       code = tscGetSTableVgroupInfo(pSql, pCmd->clauseIndex);
       if (code == TSDB_CODE_TSC_ACTION_IN_PROGRESS) {
+        taosReleaseRef(tscObjRef, pSql->self);
         return;
       } else if (code != TSDB_CODE_SUCCESS) {
         goto _error;
@@ -522,10 +534,15 @@ void tscTableMetaCallBack(void *param, TAOS_RES *res, int code) {
 
     (*pSql->fp)(pSql->param, pSql, code);
 
+    taosReleaseRef(tscObjRef, pSql->self);
+    
     return;
   }
 
   tscDoQuery(pSql);
+
+  taosReleaseRef(tscObjRef, pSql->self);
+  
   return;
 
   _error:
@@ -533,4 +550,6 @@ void tscTableMetaCallBack(void *param, TAOS_RES *res, int code) {
     pSql->res.code = code;
     tscAsyncResultOnError(pSql);
   }
+
+  taosReleaseRef(tscObjRef, pSql->self);
 }
diff --git a/src/client/src/tscServer.c b/src/client/src/tscServer.c
index 4949aa9b9dab6efb96f411f433ec420c6fd6d338..e72042e7ab9ef36e17c57977585e49acb7f7334a 100644
--- a/src/client/src/tscServer.c
+++ b/src/client/src/tscServer.c
@@ -423,7 +423,7 @@ void tscProcessMsgFromServer(SRpcMsg *rpcMsg, SRpcEpSet *pEpSet) {
 
   if (shouldFree) { // in case of table-meta/vgrouplist query, automatically free it
     taosRemoveRef(tscObjRef, pSql->self);
-    tscDebug("%p sqlObj is automatically freed", pSql);
+    tscDebug("%p sqlObj is automatically freed", pSql); 
   }
 
   rpcFreeCont(rpcMsg->pCont);
@@ -1992,16 +1992,20 @@ int tscProcessMultiMeterMetaRsp(SSqlObj *pSql) {
 }
 
 int tscProcessSTableVgroupRsp(SSqlObj *pSql) {
+  // master sqlObj locates in param
+  SSqlObj* parent = (SSqlObj*)taosAcquireRef(tscObjRef, (int64_t)pSql->param);
+  if(parent == NULL) {
+    return pSql->res.code;
+  }
+
+  assert(parent->signature == parent && (int64_t)pSql->param == parent->self);
+  
   SSqlRes* pRes = &pSql->res;
   
   // NOTE: the order of several table must be preserved.
   SSTableVgroupRspMsg *pStableVgroup = (SSTableVgroupRspMsg *)pRes->pRsp;
   pStableVgroup->numOfTables = htonl(pStableVgroup->numOfTables);
   char *pMsg = pRes->pRsp + sizeof(SSTableVgroupRspMsg);
-
-  // master sqlObj locates in param
-  SSqlObj* parent = pSql->param;
-  assert(parent != NULL);
   
   SSqlCmd* pCmd = &parent->cmd;
   for(int32_t i = 0; i < pStableVgroup->numOfTables; ++i) {
@@ -2035,6 +2039,8 @@ int tscProcessSTableVgroupRsp(SSqlObj *pSql) {
 
     pMsg += size;
   }
+
+  taosReleaseRef(tscObjRef, parent->self);
   
   return pSql->res.code;
 }
@@ -2328,10 +2334,14 @@ static int32_t getTableMetaFromMnode(SSqlObj *pSql, STableMetaInfo *pTableMetaIn
 
   tscDebug("%p new pSqlObj:%p to get tableMeta, auto create:%d", pSql, pNew, pNew->cmd.autoCreated);
 
+  registerSqlObj(pNew);
+
   pNew->fp = tscTableMetaCallBack;
-  pNew->param = pSql;
+  pNew->param = (void *)pSql->self;
 
-  registerSqlObj(pNew);
+  tscDebug("%p metaRid from %" PRId64 " to %" PRId64 , pSql, pSql->metaRid, pNew->self);
+  
+  pSql->metaRid = pNew->self;
 
   int32_t code = tscProcessSql(pNew);
   if (code == TSDB_CODE_SUCCESS) {
@@ -2348,6 +2358,7 @@ int32_t tscGetTableMeta(SSqlObj *pSql, STableMetaInfo *pTableMetaInfo) {
   uint32_t size = tscGetTableMetaMaxSize();
   pTableMetaInfo->pTableMeta = calloc(1, size);
 
+  pTableMetaInfo->pTableMeta->tableType = -1;
   pTableMetaInfo->pTableMeta->tableInfo.numOfColumns  = -1;
   int32_t len = (int32_t) strlen(pTableMetaInfo->name);
 
@@ -2447,10 +2458,15 @@ int tscGetSTableVgroupInfo(SSqlObj *pSql, int32_t clauseIndex) {
   pNewQueryInfo->numOfTables = pQueryInfo->numOfTables;
   registerSqlObj(pNew);
 
+  tscDebug("%p svgroupRid from %" PRId64 " to %" PRId64 , pSql, pSql->svgroupRid, pNew->self);
+  
+  pSql->svgroupRid = pNew->self;
+  
+
   tscDebug("%p new sqlObj:%p to get vgroupInfo, numOfTables:%d", pSql, pNew, pNewQueryInfo->numOfTables);
 
   pNew->fp = tscTableMetaCallBack;
-  pNew->param = pSql;
+  pNew->param = (void *)pSql->self;
   code = tscProcessSql(pNew);
   if (code == TSDB_CODE_SUCCESS) {
     code = TSDB_CODE_TSC_ACTION_IN_PROGRESS;
diff --git a/src/client/src/tscSql.c b/src/client/src/tscSql.c
index 377cb24b1d5b1c92c702cd113c4feea185617911..4f5243b15a7ac0dc809d631790a408d0f01853ca 100644
--- a/src/client/src/tscSql.c
+++ b/src/client/src/tscSql.c
@@ -694,6 +694,8 @@ static void tscKillSTableQuery(SSqlObj *pSql) {
   // set the master sqlObj flag to cancel query
   pSql->res.code = TSDB_CODE_TSC_QUERY_CANCELLED;
 
+  tscLockByThread(&pSql->squeryLock);
+  
   for (int i = 0; i < pSql->subState.numOfSub; ++i) {
     // NOTE: pSub may have been released already here
     SSqlObj *pSub = pSql->pSubs[i];
@@ -713,6 +715,12 @@ static void tscKillSTableQuery(SSqlObj *pSql) {
     taosReleaseRef(tscObjRef, pSubObj->self);
   }
 
+  if (pSql->subState.numOfSub <= 0) {
+    tscAsyncResultOnError(pSql);
+  }
+
+  tscUnlockByThread(&pSql->squeryLock);
+
   tscDebug("%p super table query cancelled", pSql);
 }
 
diff --git a/src/client/src/tscSubquery.c b/src/client/src/tscSubquery.c
index 96fdde4fd61958efbf306a3b578a4b357a3ea930..76e3456b7e232d3ac0884b43755da989c85f9ffb 100644
--- a/src/client/src/tscSubquery.c
+++ b/src/client/src/tscSubquery.c
@@ -533,7 +533,7 @@ static void quitAllSubquery(SSqlObj* pSqlObj, SJoinSupporter* pSupporter) {
     freeJoinSubqueryObj(pSqlObj);
   }
 
-  tscDestroyJoinSupporter(pSupporter);
+  //tscDestroyJoinSupporter(pSupporter);
 }
 
 // update the query time range according to the join results on timestamp
@@ -1658,6 +1658,25 @@ static void doCleanupSubqueries(SSqlObj *pSql, int32_t numOfSubs) {
   }
 }
 
+void tscLockByThread(int64_t *lockedBy) {
+  int64_t tid = taosGetSelfPthreadId();
+  int     i = 0;
+  while (atomic_val_compare_exchange_64(lockedBy, 0, tid) != 0) {
+    if (++i % 100 == 0) {
+      sched_yield();
+    }
+  }
+}
+
+void tscUnlockByThread(int64_t *lockedBy) {
+  int64_t tid = taosGetSelfPthreadId();
+  if (atomic_val_compare_exchange_64(lockedBy, tid, 0) != tid) {
+    assert(false);
+  }
+}
+
+
+
 int32_t tscHandleMasterSTableQuery(SSqlObj *pSql) {
   SSqlRes *pRes = &pSql->res;
   SSqlCmd *pCmd = &pSql->cmd;
diff --git a/src/client/src/tscUtil.c b/src/client/src/tscUtil.c
index 5d818692ed90480c4b461c1fe8aba9d785dee694..7774ad348c895f4d0a8eefac8818dafb60de7241 100644
--- a/src/client/src/tscUtil.c
+++ b/src/client/src/tscUtil.c
@@ -467,6 +467,18 @@ void tscFreeRegisteredSqlObj(void *pSql) {
 
 }
 
+void tscFreeMetaSqlObj(int64_t *rid){
+  if (RID_VALID(*rid)) {
+    SSqlObj* pSql = (SSqlObj*)taosAcquireRef(tscObjRef, *rid);
+    if (pSql) {
+      taosRemoveRef(tscObjRef, *rid);
+      taosReleaseRef(tscObjRef, *rid);
+    }
+
+    *rid = 0;
+  }
+}
+
 void tscFreeSqlObj(SSqlObj* pSql) {
   if (pSql == NULL || pSql->signature != pSql) {
     return;
@@ -476,6 +488,9 @@ void tscFreeSqlObj(SSqlObj* pSql) {
 
   pSql->res.code = TSDB_CODE_TSC_QUERY_CANCELLED;
 
+  tscFreeMetaSqlObj(&pSql->metaRid);
+  tscFreeMetaSqlObj(&pSql->svgroupRid);
+
   tscFreeSubobj(pSql);
 
   SSqlCmd* pCmd = &pSql->cmd;
@@ -504,6 +519,7 @@ void tscFreeSqlObj(SSqlObj* pSql) {
   pCmd->allocSize = 0;
   
   tsem_destroy(&pSql->rspSem);
+  memset(pSql, 0, sizeof(*pSql));
   free(pSql);
 }
 
@@ -2192,7 +2208,9 @@ void tscDoQuery(SSqlObj* pSql) {
           tscProcessSql(pSql);
         } else { // secondary stage join query.
           if (tscIsTwoStageSTableQuery(pQueryInfo, 0)) {  // super table query
+            tscLockByThread(&pSql->squeryLock);
             tscHandleMasterSTableQuery(pSql);
+            tscUnlockByThread(&pSql->squeryLock);
           } else {
             tscProcessSql(pSql);
           }
@@ -2201,7 +2219,9 @@ void tscDoQuery(SSqlObj* pSql) {
 
       return;
     } else if (tscIsTwoStageSTableQuery(pQueryInfo, 0)) {  // super table query
+      tscLockByThread(&pSql->squeryLock);
       tscHandleMasterSTableQuery(pSql);
+      tscUnlockByThread(&pSql->squeryLock);
       return;
     }