diff --git a/src/client/src/tscSubquery.c b/src/client/src/tscSubquery.c
index f3af685cebfc8daea679777362d55fc09cc3c3a1..45bcf4095ac2b8c4b74fbfed45f8e3bf8f891091 100644
--- a/src/client/src/tscSubquery.c
+++ b/src/client/src/tscSubquery.c
@@ -2433,6 +2433,26 @@ int32_t tscHandleFirstRoundStableQuery(SSqlObj *pSql) {
   return terrno;
 }
 
+typedef struct SPair {
+  int32_t first;
+  int32_t second;
+} SPair;
+
+static void doSendQueryReqs(SSchedMsg* pSchedMsg) {
+  SSqlObj* pSql = pSchedMsg->ahandle;
+  SPair* p = pSchedMsg->msg;
+
+  for(int32_t i = p->first; i < p->second; ++i) {
+    SSqlObj* pSub = pSql->pSubs[i];
+    SRetrieveSupport* pSupport = pSub->param;
+
+    tscDebug("0x%"PRIx64" sub:0x%"PRIx64" launch subquery, orderOfSub:%d.", pSql->self, pSub->self, pSupport->subqueryIndex);
+    tscBuildAndSendRequest(pSub, NULL);
+  }
+
+  tfree(p);
+}
+
 int32_t tscHandleMasterSTableQuery(SSqlObj *pSql) {
   SSqlRes *pRes = &pSql->res;
   SSqlCmd *pCmd = &pSql->cmd;
@@ -2555,13 +2575,33 @@ int32_t tscHandleMasterSTableQuery(SSqlObj *pSql) {
     doCleanupSubqueries(pSql, i);
     return pRes->code;
   }
-  
-  for(int32_t j = 0; j < pState->numOfSub; ++j) {
-    SSqlObj* pSub = pSql->pSubs[j];
-    SRetrieveSupport* pSupport = pSub->param;
-    
-    tscDebug("0x%"PRIx64" sub:0x%"PRIx64" launch subquery, orderOfSub:%d.", pSql->self, pSub->self, pSupport->subqueryIndex);
-    tscBuildAndSendRequest(pSub, NULL);
+
+  // concurrently sent the query requests.
+  const int32_t MAX_REQUEST_PER_TASK = 8;
+
+  int32_t numOfTasks = (pState->numOfSub + MAX_REQUEST_PER_TASK - 1)/MAX_REQUEST_PER_TASK;
+  assert(numOfTasks >= 1);
+
+  int32_t num = (pState->numOfSub/numOfTasks) + 1;
+  tscDebug("0x%"PRIx64 " query will be sent by %d threads", pSql->self, numOfTasks);
+
+  for(int32_t j = 0; j < numOfTasks; ++j) {
+    SSchedMsg schedMsg = {0};
+    schedMsg.fp      = doSendQueryReqs;
+    schedMsg.ahandle = (void*)pSql;
+
+    schedMsg.thandle = NULL;
+    SPair* p = calloc(1, sizeof(SPair));
+    p->first  = j * num;
+
+    if (j == numOfTasks - 1) {
+      p->second = pState->numOfSub;
+    } else {
+      p->second = (j + 1) * num;
+    }
+
+    schedMsg.msg = p;
+    taosScheduleTask(tscQhandle, &schedMsg);
   }
 
   return TSDB_CODE_SUCCESS;
diff --git a/src/query/src/qExecutor.c b/src/query/src/qExecutor.c
index 303612fc8e663e0a304ee1556500456be7720c10..0e2aba1d247657f6d4199817614fc08f282d7333 100644
--- a/src/query/src/qExecutor.c
+++ b/src/query/src/qExecutor.c
@@ -4265,6 +4265,7 @@ static void doCopyQueryResultToMsg(SQInfo *pQInfo, int32_t numOfRows, char *data
   }
 
   qDebug("QInfo:0x%"PRIx64" set %d subscribe info", pQInfo->qId, total);
+
   // Check if query is completed or not for stable query or normal table query respectively.
   if (Q_STATUS_EQUAL(pRuntimeEnv->status, QUERY_COMPLETED) && pRuntimeEnv->proot->status == OP_EXEC_DONE) {
     setQueryStatus(pRuntimeEnv, QUERY_OVER);
@@ -7079,6 +7080,10 @@ static SSDataBlock* doTagScan(void* param, bool* newgroup) {
     qDebug("QInfo:0x%"PRIx64" create tag values results completed, rows:%d", GET_QID(pRuntimeEnv), count);
   }
 
+  if (pOperator->status == OP_EXEC_DONE) {
+    setQueryStatus(pOperator->pRuntimeEnv, QUERY_COMPLETED);
+  }
+
   pRes->info.rows = count;
   return (pRes->info.rows == 0)? NULL:pInfo->pRes;
 }