diff --git a/src/client/inc/tscUtil.h b/src/client/inc/tscUtil.h
index 590f205e1da87d3bc434f374b6c173905a46c184..72ca96891acb2ecbab27aedf47b2e97fc4a487d6 100644
--- a/src/client/inc/tscUtil.h
+++ b/src/client/inc/tscUtil.h
@@ -270,6 +270,9 @@ void tscAsyncQuerySingleRowForNextVnode(void *param, TAOS_RES *tres, int numOfRo
 void tscTryQueryNextClause(SSqlObj* pSql, __async_cb_func_t fp);
 int  tscSetMgmtEpSetFromCfg(const char *first, const char *second);
 
+bool tscSetSqlOwner(SSqlObj* pSql);
+void tscClearSqlOwner(SSqlObj* pSql);
+
 void* malloc_throw(size_t size);
 void* calloc_throw(size_t nmemb, size_t size);
 char* strdup_throw(const char* str);
diff --git a/src/client/inc/tsclient.h b/src/client/inc/tsclient.h
index 3ad4cd9455e84dda50bbc8297f37bece022d6b09..49f7cec8893cc425ab4e35b53e192ec9ee57e7e7 100644
--- a/src/client/inc/tsclient.h
+++ b/src/client/inc/tsclient.h
@@ -302,6 +302,7 @@ typedef struct STscObj {
 
 typedef struct SSqlObj {
   void            *signature;
+  pthread_t        owner;        // owner of sql object, by which it is executed
   STscObj         *pTscObj;
   void            *pRpcCtx;
   void            (*fp)();
diff --git a/src/client/src/tscSql.c b/src/client/src/tscSql.c
index af8e913563e74a6a86e682ec5b278820a9d00569..f01f1aa384876af2534bb60a7b5c67f3dd62e40a 100644
--- a/src/client/src/tscSql.c
+++ b/src/client/src/tscSql.c
@@ -233,48 +233,21 @@ static void waitForRetrieveRsp(void *param, TAOS_RES *tres, int numOfRows) {
   sem_post(&pSql->rspSem);
 }
 
-TAOS_RES* taos_query(TAOS *taos, const char *sqlstr) {
+TAOS_RES* taos_query_c(TAOS *taos, const char *sqlstr, uint32_t sqlLen) {
   STscObj *pObj = (STscObj *)taos;
   if (pObj == NULL || pObj->signature != pObj) {
     terrno = TSDB_CODE_TSC_DISCONNECTED;
     return NULL;
   }
   
-  int32_t sqlLen = strlen(sqlstr);
   if (sqlLen > tsMaxSQLStringLen) {
     tscError("sql string exceeds max length:%d", tsMaxSQLStringLen);
     terrno = TSDB_CODE_TSC_INVALID_SQL;
     return NULL;
   }
-  
+
   taosNotePrintTsc(sqlstr);
-  
-  SSqlObj* pSql = calloc(1, sizeof(SSqlObj));
-  if (pSql == NULL) {
-    tscError("failed to malloc sqlObj");
-    terrno = TSDB_CODE_TSC_OUT_OF_MEMORY;
-    return NULL;
-  }
-  
-  doAsyncQuery(pObj, pSql, waitForQueryRsp, taos, sqlstr, sqlLen);
 
-  // wait for the callback function to post the semaphore
-  tsem_wait(&pSql->rspSem);
-  return pSql;
-}
-TAOS_RES* taos_query_c(TAOS *taos, const char *sqlstr, uint32_t sqlLen) {
-  STscObj *pObj = (STscObj *)taos;
-  if (pObj == NULL || pObj->signature != pObj) {
-    terrno = TSDB_CODE_TSC_DISCONNECTED;
-    return NULL;
-  }
-  
-  if (sqlLen > tsMaxSQLStringLen) {
-    tscError("sql string exceeds max length:%d", tsMaxSQLStringLen);
-    terrno = TSDB_CODE_TSC_INVALID_SQL;
-    return NULL;
-  }
-  
   SSqlObj* pSql = calloc(1, sizeof(SSqlObj));
   if (pSql == NULL) {
     tscError("failed to malloc sqlObj");
@@ -287,6 +260,11 @@ TAOS_RES* taos_query_c(TAOS *taos, const char *sqlstr, uint32_t sqlLen) {
   tsem_wait(&pSql->rspSem);
   return pSql; 
 }
+
+TAOS_RES* taos_query(TAOS *taos, const char *sqlstr) {
+  return taos_query_c(taos, sqlstr, strlen(sqlstr));
+}
+
 int taos_result_precision(TAOS_RES *res) {
   SSqlObj *pSql = (SSqlObj *)res;
   if (pSql == NULL || pSql->signature != pSql) return 0;
@@ -422,7 +400,10 @@ TAOS_ROW taos_fetch_row(TAOS_RES *res) {
       pCmd->command == TSDB_SQL_INSERT) {
     return NULL;
   }
-  
+
+  // set the sql object owner
+  tscSetSqlOwner(pSql);
+
   // current data set are exhausted, fetch more data from node
   if (pRes->row >= pRes->numOfRows && (pRes->completed != true || hasMoreVnodesToTry(pSql) || hasMoreClauseToTry(pSql)) &&
       (pCmd->command == TSDB_SQL_RETRIEVE ||
@@ -441,7 +422,10 @@ TAOS_ROW taos_fetch_row(TAOS_RES *res) {
     sem_wait(&pSql->rspSem);
   }
 
-  return doSetResultRowData(pSql, true);
+  void* data = doSetResultRowData(pSql, true);
+
+  tscClearSqlOwner(pSql);
+  return data;
 }
 
 int taos_fetch_block(TAOS_RES *res, TAOS_ROW *rows) {
@@ -509,7 +493,7 @@ int taos_select_db(TAOS *taos, const char *db) {
 }
 
 // send free message to vnode to free qhandle and corresponding resources in vnode
-static bool tscFreeQhandleInVnode(SSqlObj* pSql) {
+static bool tscKillQueryInVnode(SSqlObj* pSql) {
   SSqlCmd* pCmd = &pSql->cmd;
   SSqlRes* pRes = &pSql->res;
 
@@ -557,16 +541,14 @@ void taos_free_result(TAOS_RES *res) {
   }
 
   pQueryInfo->type = TSDB_QUERY_TYPE_FREE_RESOURCE;
-  if (!tscFreeQhandleInVnode(pSql)) {
+  if (!tscKillQueryInVnode(pSql)) {
     tscFreeSqlObj(pSql);
     tscDebug("%p sqlObj is freed by app", pSql);
   }
 }
 
-// todo should not be used in async query
 int taos_errno(TAOS_RES *tres) {
   SSqlObj *pSql = (SSqlObj *) tres;
-
   if (pSql == NULL || pSql->signature != pSql) {
     return terrno;
   }
diff --git a/src/client/src/tscUtil.c b/src/client/src/tscUtil.c
index 5409d909398bfe5570aef25dd6145f078b3c81cc..fdc019e97b0b90f8848f4b0cbfb0f7ba644b820b 100644
--- a/src/client/src/tscUtil.c
+++ b/src/client/src/tscUtil.c
@@ -2223,3 +2223,21 @@ int tscSetMgmtEpSetFromCfg(const char *first, const char *second) {
 
   return 0;
 }
+
+bool tscSetSqlOwner(SSqlObj* pSql) {
+  SSqlRes* pRes = &pSql->res;
+
+  // set the sql object owner
+  uint64_t threadId = taosGetPthreadId();
+  if (atomic_val_compare_exchange_64(&pSql->owner, 0, threadId) != 0) {
+    pRes->code = TSDB_CODE_QRY_IN_EXEC;
+    return false;
+  }
+
+  return true;
+}
+
+void tscClearSqlOwner(SSqlObj* pSql) {
+  assert(pSql->owner != 0);
+  atomic_store_64(&pSql->owner, 0);
+}
\ No newline at end of file