diff --git a/src/client/inc/tsclient.h b/src/client/inc/tsclient.h
index bd956aeb74..90364987bb 100644
--- a/src/client/inc/tsclient.h
+++ b/src/client/inc/tsclient.h
@@ -349,7 +349,7 @@ typedef struct SSqlStream {
 int32_t tscInitRpc(const char *user, const char *secret, void** pDnodeConn);
 void    tscInitMsgsFp();
 
-int tsParseSql(SSqlObj *pSql, bool multiVnodeInsertion);
+int tsParseSql(SSqlObj *pSql, bool initialParse);
 
 void tscProcessMsgFromServer(SRpcMsg *rpcMsg, SRpcIpSet *pIpSet);
 int  tscProcessSql(SSqlObj *pSql);
diff --git a/src/client/src/tscAsync.c b/src/client/src/tscAsync.c
index 3c54176d0a..2b99d23099 100644
--- a/src/client/src/tscAsync.c
+++ b/src/client/src/tscAsync.c
@@ -39,41 +39,26 @@ static void tscProcessAsyncRetrieveImpl(void *param, TAOS_RES *tres, int numOfRo
 static void tscAsyncFetchRowsProxy(void *param, TAOS_RES *tres, int numOfRows);
 static void tscAsyncFetchSingleRowProxy(void *param, TAOS_RES *tres, int numOfRows);
 
-int doAsyncParseSql(SSqlObj* pSql) {
-  SSqlCmd* pCmd = &pSql->cmd;
-  SSqlRes* pRes = &pSql->res;
-
-  int32_t code = tscAllocPayload(pCmd, TSDB_DEFAULT_PAYLOAD_SIZE);
-  if (code != TSDB_CODE_SUCCESS) {
-    tscError("failed to malloc payload");
-    pSql->res.code = code;
-
-    tscQueueAsyncRes(pSql);
-    return code;
-  }
-  
-  pRes->qhandle = 0;
-  pRes->numOfRows = 1;
-  
-  tscDump("%p SQL: %s", pSql, pSql->sqlstr);
-  return tsParseSql(pSql, true);
-}
-
 void doAsyncQuery(STscObj* pObj, SSqlObj* pSql, void (*fp)(), void* param, const char* sqlstr, size_t sqlLen) {
   pSql->signature = pSql;
   pSql->param     = param;
   pSql->pTscObj   = pObj;
   pSql->maxRetry  = TSDB_MAX_REPLICA_NUM;
   pSql->fp        = fp;
+
   pSql->sqlstr = calloc(1, sqlLen + 1);
   if (pSql->sqlstr == NULL) {
     tscError("%p failed to malloc sql string buffer", pSql);
     tscQueueAsyncError(pSql->fp, pSql->param, TSDB_CODE_TSC_OUT_OF_MEMORY);
     return;
   }
+
   strtolower(pSql->sqlstr, sqlstr);
-  
-  int32_t code = doAsyncParseSql(pSql);
+
+  tscDump("%p SQL: %s", pSql, pSql->sqlstr);
+  pSql->cmd.curSql = pSql->sqlstr;
+
+  int32_t code = tsParseSql(pSql, true);
   if (code == TSDB_CODE_TSC_ACTION_IN_PROGRESS) return;
   
   if (code != TSDB_CODE_SUCCESS) {
diff --git a/src/client/src/tscParseInsert.c b/src/client/src/tscParseInsert.c
index 4b6178eb61..b03972bbfa 100644
--- a/src/client/src/tscParseInsert.c
+++ b/src/client/src/tscParseInsert.c
@@ -1014,42 +1014,37 @@ static int32_t validateDataSource(SSqlCmd *pCmd, int8_t type, const char *sql) {
  * @param pSql
  * @return
  */
-int doParseInsertSql(SSqlObj *pSql, char *str) {
+int tsParseInsertSql(SSqlObj *pSql) {
   SSqlCmd *pCmd = &pSql->cmd;
+  char* str = pCmd->curSql;
 
   int32_t totalNum = 0;
   int32_t code = TSDB_CODE_SUCCESS;
 
-  STableMetaInfo *pTableMetaInfo = NULL;
-
   SQueryInfo *pQueryInfo = tscGetQueryInfoDetail(pCmd, 0);
   assert(pQueryInfo != NULL);
 
+  STableMetaInfo *pTableMetaInfo = NULL;
   if (pQueryInfo->numOfTables == 0) {
     pTableMetaInfo = tscAddEmptyMetaInfo(pQueryInfo);
   } else {
     pTableMetaInfo = tscGetMetaInfo(pQueryInfo, 0);
   }
 
-  // TODO: 2048 is added because TSDB_MAX_TAGS_LEN now is 65536
-  // but TSDB_PAYLOAD_SIZE is 65380
+  // TODO: 2048 is added because TSDB_MAX_TAGS_LEN now is 65536, but TSDB_PAYLOAD_SIZE is 65380
   if ((code = tscAllocPayload(pCmd, TSDB_PAYLOAD_SIZE + 2048)) != TSDB_CODE_SUCCESS) {
     return code;
   }
 
-  assert(((NULL == pCmd->curSql) && (NULL == pCmd->pTableList))
-      || ((NULL != pCmd->curSql) && (NULL != pCmd->pTableList)));
-
-  if ((NULL == pCmd->curSql) && (NULL == pCmd->pTableList)) {
+  if (NULL == pCmd->pTableList) {
     pCmd->pTableList = taosHashInit(128, taosGetDefaultHashFunction(TSDB_DATA_TYPE_BIGINT), false);
 
     pSql->cmd.pDataBlocks = tscCreateBlockArrayList();
     if (NULL == pCmd->pTableList || NULL == pSql->cmd.pDataBlocks) {
       code = TSDB_CODE_TSC_OUT_OF_MEMORY;
-      goto _error_clean;
+      goto _error;
     }
   } else {
-    assert((NULL != pCmd->curSql) && (NULL != pCmd->pTableList));
     str = pCmd->curSql;
   }
   
@@ -1075,7 +1070,7 @@ int doParseInsertSql(SSqlObj *pSql, char *str) {
        */
       if (totalNum == 0) {
         code = TSDB_CODE_TSC_INVALID_SQL;
-        goto _error_clean;
+        goto _error;
       } else {
         break;
       }
@@ -1086,11 +1081,11 @@ int doParseInsertSql(SSqlObj *pSql, char *str) {
     // Check if the table name available or not
     if (validateTableName(sToken.z, sToken.n) != TSDB_CODE_SUCCESS) {
       code = tscInvalidSQLErrMsg(pCmd->payload, "table name invalid", sToken.z);
-      goto _error_clean;
+      goto _error;
     }
 
     if ((code = tscSetTableFullName(pTableMetaInfo, &sToken, pSql)) != TSDB_CODE_SUCCESS) {
-      goto _error_clean;
+      goto _error;
     }
 
     ptrdiff_t pos = pCmd->curSql - pSql->sqlstr;
@@ -1103,20 +1098,19 @@ int doParseInsertSql(SSqlObj *pSql, char *str) {
        * interrupted position.
        */
       if (TSDB_CODE_TSC_ACTION_IN_PROGRESS == code) {
-        tscTrace("%p waiting for get table meta during insert, then resume from offset: %" PRId64 " , %s", pSql,
+        tscTrace("%p waiting for get table meta during insert, then resume from offset: %" PRId64 ", %s", pSql,
             pos, pCmd->curSql);
         return code;
       }
       
-      // todo add to return
-      tscError("%p async insert parse error, code:%d, %s", pSql, code, tstrerror(code));
+      tscError("%p async insert parse error, code:%d, reason:%s", pSql, code, tstrerror(code));
       pCmd->curSql = NULL;
-      goto _error_clean;       // TODO: should _clean or _error_clean to async flow ????
+      goto _error;
     }
 
     if (UTIL_TABLE_IS_SUPER_TABLE(pTableMetaInfo)) {
       code = tscInvalidSQLErrMsg(pCmd->payload, "insert data into super table is not supported", NULL);
-      goto _error_clean;
+      goto _error;
     }
 
     index = 0;
@@ -1125,7 +1119,7 @@ int doParseInsertSql(SSqlObj *pSql, char *str) {
 
     if (sToken.n == 0) {
       code = tscInvalidSQLErrMsg(pCmd->payload, "keyword VALUES or FILE required", sToken.z);
-      goto _error_clean;
+      goto _error;
     }
     
     STableComInfo tinfo = tscGetTableInfo(pTableMetaInfo->pTableMeta);
@@ -1137,7 +1131,7 @@ int doParseInsertSql(SSqlObj *pSql, char *str) {
       tscSetAssignedColumnInfo(&spd, pSchema, tinfo.numOfColumns);
 
       if (validateDataSource(pCmd, DATA_FROM_SQL_STRING, sToken.z) != TSDB_CODE_SUCCESS) {
-        goto _error_clean;
+        goto _error;
       }
 
       /*
@@ -1146,11 +1140,11 @@ int doParseInsertSql(SSqlObj *pSql, char *str) {
        */
       code = doParseInsertStatement(pSql, pCmd->pTableList, &str, &spd, &totalNum);
       if (code != TSDB_CODE_SUCCESS) {
-        goto _error_clean;
+        goto _error;
       }
     } else if (sToken.type == TK_FILE) {
       if (validateDataSource(pCmd, DATA_FROM_DATA_FILE, sToken.z) != TSDB_CODE_SUCCESS) {
-        goto _error_clean;
+        goto _error;
       }
 
       index = 0;
@@ -1158,7 +1152,7 @@ int doParseInsertSql(SSqlObj *pSql, char *str) {
       str += index;
       if (sToken.n == 0) {
         code = tscInvalidSQLErrMsg(pCmd->payload, "file path is required following keyword FILE", sToken.z);
-        goto _error_clean;
+        goto _error;
       }
 
       char fname[PATH_MAX] = {0};
@@ -1168,7 +1162,7 @@ int doParseInsertSql(SSqlObj *pSql, char *str) {
       wordexp_t full_path;
       if (wordexp(fname, &full_path, 0) != 0) {
         code = tscInvalidSQLErrMsg(pCmd->payload, "invalid filename", sToken.z);
-        goto _error_clean;
+        goto _error;
       }
       strcpy(fname, full_path.we_wordv[0]);
       wordfree(&full_path);
@@ -1179,7 +1173,7 @@ int doParseInsertSql(SSqlObj *pSql, char *str) {
       int32_t ret = tscCreateDataBlock(PATH_MAX, tinfo.rowSize, sizeof(SSubmitBlk), pTableMetaInfo->name,
                                        pTableMeta, &pDataBlock);
       if (ret != TSDB_CODE_SUCCESS) {
-        goto _error_clean;
+        goto _error;
       }
 
       tscAppendDataBlock(pCmd->pDataBlocks, pDataBlock);
@@ -1190,7 +1184,7 @@ int doParseInsertSql(SSqlObj *pSql, char *str) {
       SSchema *   pSchema = tscGetTableSchema(pTableMeta);
 
       if (validateDataSource(pCmd, DATA_FROM_SQL_STRING, sToken.z) != TSDB_CODE_SUCCESS) {
-        goto _error_clean;
+        goto _error;
       }
 
       SParsedDataColInfo spd = {0};
@@ -1226,7 +1220,7 @@ int doParseInsertSql(SSqlObj *pSql, char *str) {
 
             if (spd.hasVal[t] == true) {
               code = tscInvalidSQLErrMsg(pCmd->payload, "duplicated column name", sToken.z);
-              goto _error_clean;
+              goto _error;
             }
 
             spd.hasVal[t] = true;
@@ -1237,13 +1231,13 @@ int doParseInsertSql(SSqlObj *pSql, char *str) {
 
         if (!findColumnIndex) {
           code = tscInvalidSQLErrMsg(pCmd->payload, "invalid column name", sToken.z);
-          goto _error_clean;
+          goto _error;
         }
       }
 
       if (spd.numOfAssignedCols == 0 || spd.numOfAssignedCols > tinfo.numOfColumns) {
         code = tscInvalidSQLErrMsg(pCmd->payload, "column name expected", sToken.z);
-        goto _error_clean;
+        goto _error;
       }
 
       index = 0;
@@ -1252,16 +1246,16 @@ int doParseInsertSql(SSqlObj *pSql, char *str) {
 
       if (sToken.type != TK_VALUES) {
         code = tscInvalidSQLErrMsg(pCmd->payload, "keyword VALUES is expected", sToken.z);
-        goto _error_clean;
+        goto _error;
       }
 
       code = doParseInsertStatement(pSql, pCmd->pTableList, &str, &spd, &totalNum);
       if (code != TSDB_CODE_SUCCESS) {
-        goto _error_clean;
+        goto _error;
       }
     } else {
       code = tscInvalidSQLErrMsg(pCmd->payload, "keyword VALUES or FILE are required", sToken.z);
-      goto _error_clean;
+      goto _error;
     }
   }
 
@@ -1272,7 +1266,7 @@ int doParseInsertSql(SSqlObj *pSql, char *str) {
 
   if (pCmd->pDataBlocks->nSize > 0) { // merge according to vgId
     if ((code = tscMergeTableDataBlocks(pSql, pCmd->pDataBlocks)) != TSDB_CODE_SUCCESS) {
-      goto _error_clean;
+      goto _error;
     }
   } else {
     pCmd->pDataBlocks = tscDestroyBlockArrayList(pCmd->pDataBlocks);
@@ -1281,7 +1275,7 @@ int doParseInsertSql(SSqlObj *pSql, char *str) {
   code = TSDB_CODE_SUCCESS;
   goto _clean;
 
-_error_clean:
+_error:
   pCmd->pDataBlocks = tscDestroyBlockArrayList(pCmd->pDataBlocks);
 
 _clean:
@@ -1294,7 +1288,7 @@ _clean:
   return code;
 }
 
-int tsParseInsertSql(SSqlObj *pSql) {
+int tsInsertInitialCheck(SSqlObj *pSql) {
   if (!pSql->pTscObj->writeAuth) {
     return TSDB_CODE_TSC_NO_WRITE_AUTH;
   }
@@ -1312,30 +1306,23 @@ int tsParseInsertSql(SSqlObj *pSql) {
   SQueryInfo *pQueryInfo = NULL;
   tscGetQueryInfoDetailSafely(pCmd, pCmd->clauseIndex, &pQueryInfo);
 
-  TSDB_QUERY_SET_TYPE(pQueryInfo->type, TSDB_QUERY_TYPE_INSERT);
-  TSDB_QUERY_SET_TYPE(pQueryInfo->type, pCmd->insertType);
+  TSDB_QUERY_SET_TYPE(pQueryInfo->type, TSDB_QUERY_TYPE_INSERT | pCmd->insertType);
 
   sToken = tStrGetToken(pSql->sqlstr, &index, false, 0, NULL);
   if (sToken.type != TK_INTO) {
     return tscInvalidSQLErrMsg(pCmd->payload, "keyword INTO is expected", sToken.z);
   }
 
-  return doParseInsertSql(pSql, pSql->sqlstr + index);
+  pCmd->curSql = sToken.z + sToken.n;
+  return TSDB_CODE_SUCCESS;
 }
 
 int tsParseSql(SSqlObj *pSql, bool initialParse) {
   int32_t ret = TSDB_CODE_SUCCESS;
-  
-  if (initialParse) {
-    assert(!pSql->cmd.parseFinished);
+  SSqlCmd* pCmd = &pSql->cmd;
 
-    char* p = pSql->sqlstr;
-    pSql->sqlstr = NULL;
-    
-    tscPartiallyFreeSqlObj(pSql);
-    pSql->sqlstr = p;
-  } else if (!pSql->cmd.parseFinished) {
-    tscTrace("continue parse sql: %s", pSql->cmd.curSql);
+  if (!pCmd->parseFinished) {
+    tscTrace("%p resume to parse sql: %s", pSql, pCmd->curSql);
   }
   
   if (tscIsInsertData(pSql->sqlstr)) {
@@ -1347,7 +1334,11 @@ int tsParseSql(SSqlObj *pSql, bool initialParse) {
       pSql->fetchFp = pSql->fp;
       pSql->fp = (void(*)())tscHandleMultivnodeInsert;
     }
-
+    
+    if (initialParse && ((ret = tsInsertInitialCheck(pSql)) != TSDB_CODE_SUCCESS)) {
+      return ret;
+    }
+    
     ret = tsParseInsertSql(pSql);
   } else {
     ret = tscAllocPayload(&pSql->cmd, TSDB_DEFAULT_PAYLOAD_SIZE);
@@ -1362,11 +1353,9 @@ int tsParseSql(SSqlObj *pSql, bool initialParse) {
 
   /*
    * the pRes->code may be modified or released by another thread in tscTableMetaCallBack function,
-   * so do NOT use pRes->code to determine if the getTableMeta/getMetricMeta function
-   * invokes new threads to get data from mnode or simply retrieves data from cache.
-   *
-   * do NOT assign return code to pRes->code for the same reason since it may be released by another thread
-   * pRes->code = ret;
+   * so do NOT use pRes->code to determine if the getTableMeta function
+   * invokes new threads to get data from mgmt node or simply retrieves data from cache.
+   * do NOT assign return code to pRes->code for the same reason since it may be released by another thread already.
    */
   return ret;
 }
diff --git a/src/client/src/tscSQLParser.c b/src/client/src/tscSQLParser.c
index 2566e171f4..87af5fb5f7 100644
--- a/src/client/src/tscSQLParser.c
+++ b/src/client/src/tscSQLParser.c
@@ -1690,7 +1690,7 @@ int32_t addExprAndResultField(SQueryInfo* pQueryInfo, int32_t colIndex, tSQLExpr
           return invalidSqlErrMsg(pQueryInfo->msg, msg3);
         }
 
-        if (pItem->pNode->pParam->nExpr > 1 && strlen(pItem->aliasName) > 0) {
+        if (pItem->pNode->pParam->nExpr > 1 && (pItem->aliasName != NULL && strlen(pItem->aliasName) > 0)) {
           return invalidSqlErrMsg(pQueryInfo->msg, msg8);
         }
 
@@ -1761,7 +1761,7 @@ int32_t addExprAndResultField(SQueryInfo* pQueryInfo, int32_t colIndex, tSQLExpr
         int32_t numOfFields = 0;
 
         // multicolumn selection does not support alias name
-        if (strlen(pItem->aliasName) != 0) {
+        if (pItem->aliasName != NULL && strlen(pItem->aliasName) > 0) {
           return invalidSqlErrMsg(pQueryInfo->msg, msg8);
         }
 
@@ -2642,7 +2642,7 @@ static int32_t doExtractColumnFilterInfo(SQueryInfo* pQueryInfo, SColumnFilterIn
 
       tVariantDump(&pRight->val, (char*)pColumnFilter->pz, colType, false);
 
-      size_t len = wcslen((wchar_t*)pColumnFilter->pz);
+      size_t len = twcslen((wchar_t*)pColumnFilter->pz);
       pColumnFilter->len = len * TSDB_NCHAR_SIZE;
     } else {
       tVariantDump(&pRight->val, (char*)&pColumnFilter->lowerBndd, colType, false);
diff --git a/src/client/src/tscSql.c b/src/client/src/tscSql.c
index 0fa841bc7c..47a602a6fb 100644
--- a/src/client/src/tscSql.c
+++ b/src/client/src/tscSql.c
@@ -488,7 +488,7 @@ static bool tscFreeQhandleInVnode(SSqlObj* pSql) {
       (pCmd->command == TSDB_SQL_SELECT && pSql->pStream == NULL && pTableMetaInfo->pTableMeta != NULL)) {
 
     pCmd->command = (pCmd->command > TSDB_SQL_MGMT) ? TSDB_SQL_RETRIEVE : TSDB_SQL_FETCH;
-    tscTrace("%p start to send msg to free qhandle in dnode, command:%s", pSql, sqlCmd[pCmd->command]);
+    tscTrace("%p send msg to dnode to free qhandle ASAP, command:%s", pSql, sqlCmd[pCmd->command]);
     pSql->freed = 1;
     tscProcessSql(pSql);
 
@@ -510,18 +510,17 @@ static bool tscFreeQhandleInVnode(SSqlObj* pSql) {
 
 void taos_free_result(TAOS_RES *res) {
   SSqlObj *pSql = (SSqlObj *)res;
-  tscTrace("%p start to free result", res);
-  
+
   if (pSql == NULL || pSql->signature != pSql) {
-    tscTrace("%p result has been freed", pSql);
+    tscTrace("%p sqlObj has been freed", pSql);
     return;
   }
   
   // The semaphore can not be changed while freeing async sub query objects.
   SSqlRes *pRes = &pSql->res;
   if (pRes == NULL || pRes->qhandle == 0) {
-    tscTrace("%p SqlObj is freed by app, qhandle is null", pSql);
     tscFreeSqlObj(pSql);
+    tscTrace("%p SqlObj is freed by app, qhandle is null", pSql);
     return;
   }
 
@@ -529,6 +528,7 @@ void taos_free_result(TAOS_RES *res) {
   SQueryInfo *pQueryInfo = tscGetQueryInfoDetail(&pSql->cmd, 0);
   if (pQueryInfo == NULL) {
     tscFreeSqlObj(pSql);
+    tscTrace("%p SqlObj is freed by app", pSql);
     return;
   }
 
@@ -713,7 +713,6 @@ int taos_validate_sql(TAOS *taos, const char *sql) {
   SSqlRes *pRes = &pSql->res;
   SSqlCmd *pCmd = &pSql->cmd;
   
-  pRes->numOfRows  = 1;
   pRes->numOfTotal = 0;
   pRes->numOfClauseTotal = 0;
 
diff --git a/src/client/src/tscStream.c b/src/client/src/tscStream.c
index 6fc934b6c0..86a41b7ba4 100644
--- a/src/client/src/tscStream.c
+++ b/src/client/src/tscStream.c
@@ -503,8 +503,10 @@ TAOS_STREAM *taos_open_stream(TAOS *taos, const char *sqlstr, void (*fp)(void *p
   }
   strtolower(pSql->sqlstr, sqlstr);
 
+  tscDump("%p SQL: %s", pSql, pSql->sqlstr);
   tsem_init(&pSql->rspSem, 0, 0);
-  int32_t code = doAsyncParseSql(pSql);
+
+  int32_t code = tsParseSql(pSql, true);
   if (code == TSDB_CODE_TSC_ACTION_IN_PROGRESS) {
     sem_wait(&pSql->rspSem);
   }
diff --git a/src/client/src/tscSubquery.c b/src/client/src/tscSubquery.c
index aaa5ab291f..6c6284b4a6 100644
--- a/src/client/src/tscSubquery.c
+++ b/src/client/src/tscSubquery.c
@@ -1165,8 +1165,8 @@ int32_t tscLaunchJoinSubquery(SSqlObj *pSql, int16_t tableIndex, SJoinSupporter
   SQueryInfo *pQueryInfo = tscGetQueryInfoDetail(pCmd, pCmd->clauseIndex);
   
   pSql->res.qhandle = 0x1;
-  pSql->res.numOfRows = 0;
-  
+  assert(pSql->res.numOfRows == 0);
+
   if (pSql->pSubs == NULL) {
     pSql->pSubs = calloc(pSupporter->pState->numOfTotal, POINTER_BYTES);
     if (pSql->pSubs == NULL) {
@@ -1364,7 +1364,7 @@ int32_t tscHandleMasterSTableQuery(SSqlObj *pSql) {
   tOrderDescriptor *pDesc = NULL;
   SColumnModel *    pModel = NULL;
   
-  pRes->qhandle = 1;  // hack the qhandle check
+  pRes->qhandle = 0x1;  // hack the qhandle check
   
   const uint32_t nBufferSize = (1u << 16);  // 64KB
   
@@ -1845,34 +1845,41 @@ void tscRetrieveDataRes(void *param, TAOS_RES *tres, int code) {
   }
 }
 
-static void multiVnodeInsertMerge(void* param, TAOS_RES* tres, int numOfRows) {
+static void multiVnodeInsertFinalize(void* param, TAOS_RES* tres, int numOfRows) {
   SInsertSupporter *pSupporter = (SInsertSupporter *)param;
   SSqlObj* pParentObj = pSupporter->pSql;
   SSqlCmd* pParentCmd = &pParentObj->cmd;
   
   SSubqueryState* pState = pSupporter->pState;
 
-  // increase the total inserted rows
-  if (numOfRows > 0) {
-    pParentObj->res.numOfRows += numOfRows;
-  } else {
+  // record the total inserted rows
+  if (numOfRows > 0 && tres != pParentObj) {
+      pParentObj->res.numOfRows += numOfRows;
+  }
+
+  if (taos_errno(tres) != 0) {
     SSqlObj* pSql = (SSqlObj*) tres;
     assert(pSql != NULL && pSql->res.code == numOfRows);
     
     pParentObj->res.code = pSql->res.code;
   }
-  
-  taos_free_result(tres);
+
+  // it is not the initial sqlObj, free it
+  if (tres != pParentObj) {
+    taos_free_result(tres);
+  } else {
+    assert(pParentObj->pSubs[0] == tres);
+  }
+
+  tfree(pSupporter);
   if (atomic_sub_fetch_32(&pState->numOfRemain, 1) > 0) {
     return;
   }
   
   tscTrace("%p Async insertion completed, total inserted:%" PRId64, pParentObj, pParentObj->res.numOfRows);
-  
-  tfree(pState);
-  tfree(pSupporter);
-  
+
   // release data block data
+  tfree(pState);
   pParentCmd->pDataBlocks = tscDestroyBlockArrayList(pParentCmd->pDataBlocks);
   
   // restore user defined fp
@@ -1886,9 +1893,7 @@ int32_t tscHandleMultivnodeInsert(SSqlObj *pSql) {
   SSqlRes *pRes = &pSql->res;
   SSqlCmd *pCmd = &pSql->cmd;
   
-  pRes->qhandle = 1;  // hack the qhandle check
   SDataBlockList *pDataBlocks = pCmd->pDataBlocks;
-  
   pSql->pSubs = calloc(pDataBlocks->nSize, POINTER_BYTES);
   pSql->numOfSubs = pDataBlocks->nSize;
   assert(pDataBlocks->nSize > 0);
@@ -1896,52 +1901,84 @@ int32_t tscHandleMultivnodeInsert(SSqlObj *pSql) {
   tscTrace("%p submit data to %d vnode(s)", pSql, pDataBlocks->nSize);
   SSubqueryState *pState = calloc(1, sizeof(SSubqueryState));
   pState->numOfTotal = pSql->numOfSubs;
-  pState->numOfRemain = pState->numOfTotal;
-
+  pState->numOfRemain = pSql->numOfSubs;
+ 
   pRes->code = TSDB_CODE_SUCCESS;
-  
-  int32_t i = 0;
-  for (; i < pSql->numOfSubs; ++i) {
-    SInsertSupporter* pSupporter = calloc(1, sizeof(SInsertSupporter));
-    pSupporter->pSql = pSql;
-    pSupporter->pState = pState;
+
+  SInsertSupporter* pSupporter = calloc(1, sizeof(SInsertSupporter));
+  pSupporter->pSql   = pSql;
+  pSupporter->pState = pState;
+
+  pSql->fp       = multiVnodeInsertFinalize;
+  pSql->param    = pSupporter;
+  pSql->pSubs[0] = pSql;  // the first sub insert points back to itself
+  tscTrace("%p sub:%p create subObj success. orderOfSub:%d", pSql, pSql, 0);
+
+  int32_t numOfSub = 1;
+  int32_t code = tscCopyDataBlockToPayload(pSql, pDataBlocks->pData[0]);
+  if (code != TSDB_CODE_SUCCESS) {
+    tscTrace("%p prepare submit data block failed in async insertion, vnodeIdx:%d, total:%d, code:%d", pSql, 0,
+             pDataBlocks->nSize, code);
+    goto _error;
+  }
+
+  for (; numOfSub < pSql->numOfSubs; ++numOfSub) {
+    SInsertSupporter* pSupporter1 = calloc(1, sizeof(SInsertSupporter));
+    pSupporter1->pSql = pSql;
+    pSupporter1->pState = pState;
     
-    SSqlObj *pNew = createSubqueryObj(pSql, 0, multiVnodeInsertMerge, pSupporter, TSDB_SQL_INSERT, NULL);
+    SSqlObj *pNew = createSubqueryObj(pSql, 0, multiVnodeInsertFinalize, pSupporter1, TSDB_SQL_INSERT, NULL);
     if (pNew == NULL) {
-      tscError("%p failed to malloc buffer for subObj, orderOfSub:%d, reason:%s", pSql, i, strerror(errno));
-      break;
+      tscError("%p failed to malloc buffer for subObj, orderOfSub:%d, reason:%s", pSql, numOfSub, strerror(errno));
+      goto _error;
     }
   
     /*
      * assign the callback function to fetchFp to make sure that the error process function can restore
-     * the callback function (multiVnodeInsertMerge) correctly.
+     * the callback function (multiVnodeInsertFinalize) correctly.
      */
     pNew->fetchFp = pNew->fp;
-    pSql->pSubs[i] = pNew;
+    pSql->pSubs[numOfSub] = pNew;
 
-    tscTrace("%p sub:%p create subObj success. orderOfSub:%d", pSql, pNew, i);
+    code = tscCopyDataBlockToPayload(pNew, pDataBlocks->pData[numOfSub]);
+    if (code != TSDB_CODE_SUCCESS) {
+      tscTrace("%p prepare submit data block failed in async insertion, vnodeIdx:%d, total:%d, code:%d", pSql, numOfSub,
+               pDataBlocks->nSize, code);
+      goto _error;
+    } else {
+      tscTrace("%p sub:%p create subObj success. orderOfSub:%d", pSql, pNew, numOfSub);
+    }
   }
   
-  if (i < pSql->numOfSubs) {
+  if (numOfSub < pSql->numOfSubs) {
     tscError("%p failed to prepare subObj structure and launch sub-insertion", pSql);
     pRes->code = TSDB_CODE_TSC_OUT_OF_MEMORY;
     return pRes->code;  // free all allocated resource
   }
-  
-  for (int32_t j = 0; j < pSql->numOfSubs; ++j) {
+
+  // use the local variable
+  for (int32_t j = 0; j < numOfSub; ++j) {
     SSqlObj *pSub = pSql->pSubs[j];
-    int32_t code = tscCopyDataBlockToPayload(pSub, pDataBlocks->pData[j]);
-    
-    if (code != TSDB_CODE_SUCCESS) {
-      tscTrace("%p prepare submit data block failed in async insertion, vnodeIdx:%d, total:%d, code:%d", pSql, j,
-               pDataBlocks->nSize, code);
-    }
-    
     tscTrace("%p sub:%p launch sub insert, orderOfSub:%d", pSql, pSub, j);
     tscProcessSql(pSub);
   }
   
   return TSDB_CODE_SUCCESS;
+
+  _error:
+  // restore the udf fp
+  pSql->fp = pSql->fetchFp;
+  pSql->pSubs[0] = NULL;
+
+  tfree(pState);
+  tfree(pSql->param);
+
+  for(int32_t j = 1; j < numOfSub; ++j) {
+    tfree(pSql->pSubs[j]->param);
+    taos_free_result(pSql->pSubs[j]);
+  }
+
+  return TSDB_CODE_TSC_OUT_OF_MEMORY;
 }
 
 void tscBuildResFromSubqueries(SSqlObj *pSql) {
diff --git a/src/query/src/tvariant.c b/src/query/src/tvariant.c
index 1650db6cfd..1b64a7aefa 100644
--- a/src/query/src/tvariant.c
+++ b/src/query/src/tvariant.c
@@ -184,7 +184,7 @@ int32_t tVariantToString(tVariant *pVar, char *dst) {
     
     case TSDB_DATA_TYPE_NCHAR: {
       dst[0] = '\'';
-      taosUcs4ToMbs(pVar->wpz, (wcslen(pVar->wpz) + 1) * TSDB_NCHAR_SIZE, dst + 1);
+      taosUcs4ToMbs(pVar->wpz, (twcslen(pVar->wpz) + 1) * TSDB_NCHAR_SIZE, dst + 1);
       int32_t len = strlen(dst);
       dst[len] = '\'';
       dst[len + 1] = 0;
@@ -416,7 +416,7 @@ static int32_t toNchar(tVariant *pVariant, char **pDest, int32_t *pDestSize) {
     }
     
     pVariant->wpz = pWStr;
-    *pDestSize = wcslen(pVariant->wpz);
+    *pDestSize = twcslen(pVariant->wpz);
     
     // shrink the allocate memory, no need to check here.
     char* tmp = realloc(pVariant->wpz, (*pDestSize + 1)*TSDB_NCHAR_SIZE);
diff --git a/src/query/tests/unitTest.cpp b/src/query/tests/unitTest.cpp
index c5b1cbf858..59fd326ef4 100644
--- a/src/query/tests/unitTest.cpp
+++ b/src/query/tests/unitTest.cpp
@@ -66,7 +66,7 @@ static void _init_tvariant_nchar(tVariant* t) {
   t->wpz = (wchar_t*)calloc(1, 20 * TSDB_NCHAR_SIZE);
   t->nType = TSDB_DATA_TYPE_NCHAR;
   wcscpy(t->wpz, L"-2000000.8765");
-  t->nLen = wcslen(t->wpz);
+  t->nLen = twcslen(t->wpz);
 }
 
 int main(int argc, char** argv) {
diff --git a/src/util/inc/tutil.h b/src/util/inc/tutil.h
index e3e52d46ff..a314f0e31d 100644
--- a/src/util/inc/tutil.h
+++ b/src/util/inc/tutil.h
@@ -119,6 +119,8 @@ extern "C" {
 
 uint32_t taosRand(void);
 
+size_t twcslen(const wchar_t *wcs);
+
 int32_t strdequote(char *src);
 
 size_t strtrim(char *src);
diff --git a/src/util/src/tutil.c b/src/util/src/tutil.c
index 150767643f..aa5bfe322a 100644
--- a/src/util/src/tutil.c
+++ b/src/util/src/tutil.c
@@ -57,6 +57,27 @@ uint32_t taosRand(void)
 }
 #endif
 
+size_t twcslen(const wchar_t *wcs) {
+#ifdef WINDOWS
+  int *wstr = (int *)wcs;
+  if (NULL == wstr) {
+    return 0;
+  }
+
+  size_t n = 0;
+  while (1) {
+    if (0 == *wstr++) {
+      break;
+    }
+    n++;
+  }
+
+  return n;
+#else
+  return wcslen(wcs);
+#endif
+}
+
 int32_t strdequote(char *z) {
   if (z == NULL) {
     return 0;
diff --git a/tests/pytest/alter/alter_table_crash.py b/tests/pytest/alter/alter_table_crash.py
new file mode 100644
index 0000000000..903bb60e6a
--- /dev/null
+++ b/tests/pytest/alter/alter_table_crash.py
@@ -0,0 +1,83 @@
+###################################################################
+#           Copyright (c) 2016 by TAOS Technologies, Inc.
+#                     All rights reserved.
+#
+#  This file is proprietary and confidential to TAOS Technologies.
+#  No part of this file may be reproduced, stored, transmitted,
+#  disclosed or used in any form or by any means other than as
+#  expressly provided by the written permission from Jianhui Tao
+#
+###################################################################
+
+# -*- coding: utf-8 -*-
+
+import sys
+import taos
+from util.log import *
+from util.cases import *
+from util.sql import *
+from util.dnodes import *
+
+
+class TDTestCase:
+    def init(self, conn, logSql):
+        tdLog.debug("start to execute %s" % __file__)
+        tdSql.init(conn.cursor())
+
+    def run(self):
+        tdSql.prepare()
+
+        print("==============Case 1: add column, restart taosd, drop the same colum then add it back")
+        tdSql.execute(
+            "create table st(ts timestamp, speed int) tags(loc nchar(20))")
+        tdSql.execute(
+            "insert into t1 using st tags('beijing') values(now, 1)")
+        tdSql.execute(
+            "alter table st add column tbcol binary(20)")
+
+        # restart taosd
+        tdDnodes.forcestop(1)
+        tdDnodes.start(1)
+
+        tdSql.execute(
+            "alter table st drop column tbcol")
+        tdSql.execute(
+            "alter table st add column tbcol binary(20)")
+
+        tdSql.query("select * from st")
+        tdSql.checkRows(1)
+
+
+        print("==============Case 2: keep adding columns, restart taosd")
+        tdSql.execute(
+            "create table dt(ts timestamp, tbcol1 tinyint) tags(tgcol1 tinyint)")
+        tdSql.execute(
+            "alter table dt add column tbcol2 int")
+        tdSql.execute(
+            "alter table dt add column tbcol3 smallint")
+        tdSql.execute(
+            "alter table dt add column tbcol4 bigint")
+        tdSql.execute(
+            "alter table dt add column tbcol5 float")
+        tdSql.execute(
+            "alter table dt add column tbcol6 double")
+        tdSql.execute(
+            "alter table dt add column tbcol7 bool")
+        tdSql.execute(
+            "alter table dt add column tbcol8 nchar(20)")
+        tdSql.execute(
+            "alter table dt add column tbcol9 binary(20)")
+
+        # restart taosd
+        tdDnodes.forcestop(1)
+        tdDnodes.start(1)
+
+        tdSql.query("select * from st")
+        tdSql.checkRows(0)
+
+    def stop(self):
+        tdSql.close()
+        tdLog.success("%s successfully executed" % __file__)
+
+tdCases.addWindows(__file__, TDTestCase())
+tdCases.addLinux(__file__, TDTestCase())
diff --git a/tests/pytest/fulltest.sh b/tests/pytest/fulltest.sh
index dfa3b55048..0bacd63ec1 100755
--- a/tests/pytest/fulltest.sh
+++ b/tests/pytest/fulltest.sh
@@ -126,6 +126,9 @@ python3 ./test.py -f import_merge/importInsertThenImport.py
 python3 ./test.py -f user/user_create.py
 python3 ./test.py -f user/pass_len.py
 
+# stable
+python3 ./test.py -f stable/query_after_reset.py
+
 # table
 python3 ./test.py -f table/del_stable.py
 
@@ -138,7 +141,11 @@ python3 ./test.py -f query/filterAllIntTypes.py
 python3 ./test.py -f query/filterFloatAndDouble.py
 python3 ./test.py -f query/filterOtherTypes.py
 python3 ./test.py -f query/querySort.py
+python3 ./test.py -f query/queryJoin.py
 
 #stream
 python3 ./test.py -f stream/stream1.py
 python3 ./test.py -f stream/stream2.py
+
+#alter table
+python3 ./test.py -f alter/alter_table_crash.py
\ No newline at end of file
diff --git a/tests/pytest/stable/query_after_reset.py b/tests/pytest/stable/query_after_reset.py
new file mode 100644
index 0000000000..2bc171ae5d
--- /dev/null
+++ b/tests/pytest/stable/query_after_reset.py
@@ -0,0 +1,177 @@
+###################################################################
+#           Copyright (c) 2016 by TAOS Technologies, Inc.
+#                     All rights reserved.
+#
+#  This file is proprietary and confidential to TAOS Technologies.
+#  No part of this file may be reproduced, stored, transmitted,
+#  disclosed or used in any form or by any means other than as
+#  expressly provided by the written permission from Jianhui Tao
+#
+###################################################################
+
+# -*- coding: utf-8 -*-
+
+import sys
+import random
+from util.log import *
+from util.cases import *
+from util.sql import *
+from util.dnodes import *
+
+
+class Test:
+    def __init__(self):
+        self.current_tb = ""
+        self.last_tb = ""
+        self.written = 0
+
+    def create_table(self):
+        tdLog.info("create a table")
+        self.current_tb = "tb%d" % int(round(time.time() * 1000))
+        tdLog.info("current table %s" % self.current_tb)
+
+        if (self.current_tb == self.last_tb):
+            return
+        else:
+            tdSql.execute(
+                'create table %s (ts timestamp, speed int)' %
+                self.current_tb)
+            self.last_tb = self.current_tb
+            self.written = 0
+
+    def insert_data(self):
+        tdLog.info("will insert data to table")
+        if (self.current_tb == ""):
+            tdLog.info("no table, create first")
+            self.create_table()
+
+        tdLog.info("insert data to table")
+        insertRows = 10
+        tdLog.info("insert %d rows to %s" % (insertRows, self.last_tb))
+        for i in range(0, insertRows):
+            ret = tdSql.execute(
+                'insert into %s values (now + %dm, %d)' %
+                (self.last_tb, i, i))
+            self.written = self.written + 1
+
+        tdLog.info("insert earlier data")
+        tdSql.execute('insert into %s values (now - 5m , 10)' % self.last_tb)
+        self.written = self.written + 1
+        tdSql.execute('insert into %s values (now - 6m , 10)' % self.last_tb)
+        self.written = self.written + 1
+        tdSql.execute('insert into %s values (now - 7m , 10)' % self.last_tb)
+        self.written = self.written + 1
+        tdSql.execute('insert into %s values (now - 8m , 10)' % self.last_tb)
+        self.written = self.written + 1
+
+    def query_data(self):
+        if (self.written > 0):
+            tdLog.info("query data from table")
+            tdSql.query("select * from %s" % self.last_tb)
+            tdSql.checkRows(self.written)
+
+    def query_stable(self):
+        tdLog.info("query super table")
+        tdSql.query("select * from st")
+        tdSql.checkRows(1)
+
+    def create_stable(self):
+        tdLog.info("create a super table and sub-table and insert data")
+        tdSql.execute(
+            "create table if not exists st (ts timestamp, tagtype int) tags(dev nchar(50))")
+        tdSql.execute(
+            'CREATE TABLE if not exists dev_001 using st tags("dev_01")')
+        tdSql.execute(
+            "INSERT INTO dev_001(ts, tagtype) VALUES('2020-05-13 10:00:00.000', 1)")
+
+    def stop_database(self):
+        tdLog.info("stop databae")
+        tdDnodes.stop(1)
+
+    def restart_database(self):
+        tdLog.info("restart databae")
+        tdDnodes.stop(1)
+        tdDnodes.start(1)
+        tdLog.sleep(5)
+
+    def force_restart(self):
+        tdLog.info("force restart database")
+        tdDnodes.forcestop(1)
+        tdDnodes.start(1)
+        tdLog.sleep(5)
+
+    def drop_table(self):
+        if (self.current_tb != ""):
+            tdLog.info("drop current tb %s" % self.current_tb)
+            tdSql.execute("drop table %s" % self.current_tb)
+            self.current_tb = ""
+            self.last_tb = ""
+            self.written = 0
+
+    def reset_query_cache(self):
+        tdLog.info("reset query cache")
+        tdSql.execute("reset query cache")
+        tdLog.sleep(1)
+
+    def reset_database(self):
+        tdLog.info("reset database")
+        tdDnodes.forcestop(1)
+        tdDnodes.deploy(1)
+        self.current_tb = ""
+        self.last_tb = ""
+        self.written = 0
+        tdDnodes.start(1)
+        tdSql.prepare()
+
+    def delete_datafiles(self):
+        tdLog.info("delete data files")
+        dnodesDir = tdDnodes.getDnodesRootDir()
+        dataDir = dnodesDir + '/dnode1/*'
+        deleteCmd = 'rm -rf %s' % dataDir
+        os.system(deleteCmd)
+
+        self.current_tb = ""
+        self.last_tb = ""
+        self.written = 0
+        tdDnodes.start(1)
+        tdSql.prepare()
+
+
+class TDTestCase:
+    def init(self, conn, logSql):
+        tdLog.debug("start to execute %s" % __file__)
+        tdSql.init(conn.cursor(), logSql)
+
+    def run(self):
+        tdSql.prepare()
+
+        test = Test()
+
+        switch = {
+            1: test.create_table,
+            2: test.insert_data,
+            3: test.query_data,
+            4: test.create_stable,
+            5: test.restart_database,
+            6: test.force_restart,
+            7: test.drop_table,
+            8: test.reset_query_cache,
+            9: test.reset_database,
+            10: test.delete_datafiles,
+            11: test.query_stable,
+            12: test.stop_database,
+        }
+
+        switch.get(4, lambda: "ERROR")()
+        switch.get(12, lambda: "ERROR")()
+        switch.get(10, lambda: "ERROR")()
+        switch.get(5, lambda: "ERROR")()
+        switch.get(11, lambda: "ERROR")()
+
+    def stop(self):
+        tdSql.close()
+        tdLog.success("%s successfully executed" % __file__)
+
+
+tdCases.addWindows(__file__, TDTestCase())
+tdCases.addLinux(__file__, TDTestCase())