diff --git a/src/client/src/tscStream.c b/src/client/src/tscStream.c
index 20b5e86090ca39f3fba4e7b9e0a1f90b1aacb2db..6235e0aeba415627352bc3fd864eb6e35eb6086e 100644
--- a/src/client/src/tscStream.c
+++ b/src/client/src/tscStream.c
@@ -220,15 +220,16 @@ static void tscProcessStreamRetrieveResult(void *param, TAOS_RES *res, int numOf
   STableMetaInfo *pTableMetaInfo = tscGetTableMetaInfoFromCmd(&pSql->cmd, 0, 0);
 
   if (numOfRows > 0) { // when reaching here the first execution of stream computing is successful.
-    pStream->numOfRes += numOfRows;
     for(int32_t i = 0; i < numOfRows; ++i) {
       TAOS_ROW row = taos_fetch_row(res);
-      tscDebug("%p stream:%p fetch result", pSql, pStream);
-      tscStreamFillTimeGap(pStream, *(TSKEY*)row[0]);
-      pStream->stime = *(TSKEY *)row[0];
-
-      // user callback function
-      (*pStream->fp)(pStream->param, res, row);
+      if (row != NULL) {
+        tscDebug("%p stream:%p fetch result", pSql, pStream);
+        tscStreamFillTimeGap(pStream, *(TSKEY*)row[0]);
+        pStream->stime = *(TSKEY *)row[0];
+        // user callback function
+        (*pStream->fp)(pStream->param, res, row);
+        pStream->numOfRes++;
+      }
     }
 
     if (!pStream->isProject) {
diff --git a/src/client/src/tscSub.c b/src/client/src/tscSub.c
index 9569987de007c30ba30a459792a8692c24767db8..81d73236a4e9972ac4401ebbb7a5815ebe0feb4b 100644
--- a/src/client/src/tscSub.c
+++ b/src/client/src/tscSub.c
@@ -203,6 +203,7 @@ static void tscProcessSubscriptionTimer(void *handle, void *tmrId) {
 
 static SArray* getTableList( SSqlObj* pSql ) {
   const char* p = strstr( pSql->sqlstr, " from " );
+  assert(p != NULL); // we are sure this is a 'select' statement
   char* sql = alloca(strlen(p) + 32);
   sprintf(sql, "select tbid(tbname)%s", p);
   
diff --git a/src/dnode/src/dnodeTelemetry.c b/src/dnode/src/dnodeTelemetry.c
index 60277a275a331c3ecc9d8e17189e989112d0ebc1..22287f71fd10350cc5dcf80ccc32bed3c4f09822 100644
--- a/src/dnode/src/dnodeTelemetry.c
+++ b/src/dnode/src/dnodeTelemetry.c
@@ -33,7 +33,7 @@ static pthread_t tsTelemetryThread;
 
 #define TELEMETRY_SERVER "telemetry.taosdata.com"
 #define TELEMETRY_PORT 80
-#define REPORT_INTERVAL 86400
+#define REPORT_INTERVAL 86400 
 
 static void beginObject(SBufferWriter* bw) {
   tbufWriteChar(bw, '{');
@@ -220,28 +220,34 @@ static void sendTelemetryReport() {
   taosWriteSocket(fd, tbufGetData(&bw, false), contLen);
   tbufCloseWriter(&bw);
 
-  taosReadSocket(fd, buf, 10); // read something to avoid nginx error 499
+  // read something to avoid nginx error 499
+  if (taosReadSocket(fd, buf, 10) < 0) {
+    dTrace("failed to receive response, reason:%s", strerror(errno));
+  }
   taosCloseSocket(fd);
 }
 
 static void* telemetryThread(void* param) {
-  int timeToWait = 0;
+  struct timespec end = {0};
+  clock_gettime(CLOCK_REALTIME, &end);
+  end.tv_sec += 300; // wait 5 minutes to send first report
+
   while (1) {
-    if (timeToWait <= 0) {
-      if (sdbIsMaster()) {
-        sendTelemetryReport();
+    while (1) {
+      if (sem_timedwait(&tsExitSem, &end) == 0) {
+        return NULL;
+      }
+      struct timespec now = {0};
+      clock_gettime(CLOCK_REALTIME, &now);
+      if (now.tv_sec > end.tv_sec || (now.tv_sec == end.tv_sec && now.tv_nsec >= end.tv_nsec)) {
+        break;
       }
-      timeToWait = REPORT_INTERVAL;
     }
 
-    int startAt = taosGetTimestampSec();
-    struct timespec timeout = {.tv_sec = 0, .tv_nsec = 0};
-    clock_gettime(CLOCK_REALTIME, &timeout);
-    timeout.tv_sec += timeToWait;
-    if (sem_timedwait(&tsExitSem, &timeout) == 0) {
-      break;
+    if (sdbIsMaster()) {
+      sendTelemetryReport();
     }
-    timeToWait -= (taosGetTimestampSec() - startAt);
+    end.tv_sec += REPORT_INTERVAL;
   }
 
   return NULL;