diff --git a/src/client/inc/tsclient.h b/src/client/inc/tsclient.h
index 1e25c7838474de2e39be5c2e0085842c2d9e9f6b..50acbb1a49720a5260f11332620463382e9573a5 100644
--- a/src/client/inc/tsclient.h
+++ b/src/client/inc/tsclient.h
@@ -397,7 +397,7 @@ void tscFreeSqlResult(SSqlObj *pSql);
  * Note: this function is multi-thread safe.
  * @param pObj
  */
-void tscFreeSqlObjPartial(SSqlObj *pObj);
+void tscPartiallyFreeSqlObj(SSqlObj *pObj);
 
 /**
  * free sql object, release allocated resource
diff --git a/src/client/src/tscParseInsert.c b/src/client/src/tscParseInsert.c
index cab7e150230a37f968ac470de34f84b6b174d3fd..9d2458cbc4f18460747aa4af0b8547536f185437 100644
--- a/src/client/src/tscParseInsert.c
+++ b/src/client/src/tscParseInsert.c
@@ -1301,7 +1301,7 @@ int tsParseSql(SSqlObj *pSql, bool initialParse) {
     char* p = pSql->sqlstr;
     pSql->sqlstr = NULL;
     
-    tscFreeSqlObjPartial(pSql);
+    tscPartiallyFreeSqlObj(pSql);
     pSql->sqlstr = p;
   } else {
     tscTrace("continue parse sql: %s", pSql->cmd.curSql);
diff --git a/src/client/src/tscPrepare.c b/src/client/src/tscPrepare.c
index 0602fe522f42acc48646d884e7f4a972ead921b2..548c9392b06337f8ae541fbc4afcf07e2c0b42d3 100644
--- a/src/client/src/tscPrepare.c
+++ b/src/client/src/tscPrepare.c
@@ -455,7 +455,7 @@ static int insertStmtExecute(STscStmt* stmt) {
 
   // tscTrace("%p SQL result:%d, %s pObj:%p", pSql, pRes->code, taos_errstr(taos), pObj);
   if (pRes->code != TSDB_CODE_SUCCESS) {
-    tscFreeSqlObjPartial(pSql);
+    tscPartiallyFreeSqlObj(pSql);
   }
 
   return pRes->code;
diff --git a/src/client/src/tscSQLParser.c b/src/client/src/tscSQLParser.c
index 1c6f2dbd296beb84db014fd792fbf214735fbc48..f5aa4ec18eb62ababd17b826d3c715ccf0160042 100644
--- a/src/client/src/tscSQLParser.c
+++ b/src/client/src/tscSQLParser.c
@@ -2363,6 +2363,7 @@ bool hasUnsupportFunctionsForSTableQuery(SQueryInfo* pQueryInfo) {
 
 static bool functionCompatibleCheck(SQueryInfo* pQueryInfo) {
   int32_t startIdx = 0;
+  
   SSqlExpr* pExpr = tscSqlExprGet(pQueryInfo, startIdx);
   int32_t functionID = pExpr->functionId;
 
@@ -2378,14 +2379,14 @@ static bool functionCompatibleCheck(SQueryInfo* pQueryInfo) {
   size_t size = tscSqlExprNumOfExprs(pQueryInfo);
   
   for (int32_t i = startIdx + 1; i < size; ++i) {
-    SSqlExpr* pExpr = tscSqlExprGet(pQueryInfo, i);
+    SSqlExpr* pExpr1 = tscSqlExprGet(pQueryInfo, i);
 
-    int16_t functionId = pExpr->functionId;
+    int16_t functionId = pExpr1->functionId;
     if (functionId == TSDB_FUNC_TAGPRJ || functionId == TSDB_FUNC_TAG || functionId == TSDB_FUNC_TS) {
       continue;
     }
 
-    if (functionId == TSDB_FUNC_PRJ && pExpr->colInfo.colId == PRIMARYKEY_TIMESTAMP_COL_INDEX) {
+    if (functionId == TSDB_FUNC_PRJ && pExpr1->colInfo.colId == PRIMARYKEY_TIMESTAMP_COL_INDEX) {
       continue;
     }
 
@@ -3531,7 +3532,7 @@ static int32_t setTableCondForSTableQuery(SQueryInfo* pQueryInfo, const char* ac
     return TSDB_CODE_SUCCESS;
   }
 
-  SStringBuilder sb1 = { 0 };
+  SStringBuilder sb1 = {0};
   taosStringBuilderAppendStringLen(&sb1, QUERY_COND_REL_PREFIX_IN, QUERY_COND_REL_PREFIX_IN_LEN);
 
   char db[TSDB_TABLE_ID_LEN] = {0};
@@ -4030,9 +4031,7 @@ int32_t parseFillClause(SQueryInfo* pQueryInfo, SQuerySQL* pQuerySQL) {
         return invalidSqlErrMsg(pQueryInfo->msg, msg);
       }
     }
-  
-    size_t size = taosArrayGetSize(pQueryInfo->exprList);
-  
+    
     if ((pFillToken->nExpr < size) ||
         ((pFillToken->nExpr - 1 < size) && (tscIsPointInterpQuery(pQueryInfo)))) {
       tVariantListItem* lastItem = &pFillToken->a[pFillToken->nExpr - 1];
@@ -4228,7 +4227,24 @@ int32_t setAlterTableInfo(SSqlObj* pSql, struct SSqlInfo* pInfo) {
   const char* msg4 = "set tag value only available for table";
   const char* msg5 = "only support add one tag";
   const char* msg6 = "column can only be modified by super table";
-
+  
+  const char* msg7 = "no tags can be dropped";
+  const char* msg8 = "only support one tag";
+  const char* msg9 = "tag name too long";
+  
+  const char* msg10 = "invalid tag name";
+  const char* msg11 = "primary tag cannot be dropped";
+  
+  const char* msg12 = "update normal column not supported";
+  
+  const char* msg13 = "invalid tag value";
+  const char* msg14 = "tag value too long";
+  
+  const char* msg15 = "no columns can be dropped";
+  const char* msg16 = "only support one column";
+  const char* msg17 = "invalid column name";
+  const char* msg18 = "primary timestamp column cannot be dropped";
+  
   SSqlCmd*        pCmd = &pSql->cmd;
   SAlterTableSQL* pAlterSQL = pInfo->pAlterInfo;
   SQueryInfo*     pQueryInfo = tscGetQueryInfoDetail(pCmd, 0);
@@ -4274,24 +4290,18 @@ int32_t setAlterTableInfo(SSqlObj* pSql, struct SSqlInfo* pInfo) {
   
     tscFieldInfoAppend(&pQueryInfo->fieldsInfo, &pFieldList->p[0]);
   } else if (pAlterSQL->type == TSDB_ALTER_TABLE_DROP_TAG_COLUMN) {
-    const char* msg1 = "no tags can be dropped";
-    const char* msg2 = "only support one tag";
-    const char* msg3 = "tag name too long";
-    const char* msg4 = "illegal tag name";
-    const char* msg5 = "primary tag cannot be dropped";
-
     if (tscGetNumOfTags(pTableMeta) == 1) {
-      return invalidSqlErrMsg(pQueryInfo->msg, msg1);
+      return invalidSqlErrMsg(pQueryInfo->msg, msg7);
     }
 
     // numOfTags == 1
     if (pAlterSQL->varList->nExpr > 1) {
-      return invalidSqlErrMsg(pQueryInfo->msg, msg2);
+      return invalidSqlErrMsg(pQueryInfo->msg, msg8);
     }
 
     tVariantListItem* pItem = &pAlterSQL->varList->a[0];
     if (pItem->pVar.nLen > TSDB_COL_NAME_LEN) {
-      return invalidSqlErrMsg(pQueryInfo->msg, msg3);
+      return invalidSqlErrMsg(pQueryInfo->msg, msg9);
     }
 
     SColumnIndex index = COLUMN_INDEX_INITIALIZER;
@@ -4302,9 +4312,9 @@ int32_t setAlterTableInfo(SSqlObj* pSql, struct SSqlInfo* pInfo) {
     }
 
     if (index.columnIndex < tscGetNumOfColumns(pTableMeta)) {
-      return invalidSqlErrMsg(pQueryInfo->msg, msg4);
+      return invalidSqlErrMsg(pQueryInfo->msg, msg10);
     } else if (index.columnIndex == 0) {
-      return invalidSqlErrMsg(pQueryInfo->msg, msg5);
+      return invalidSqlErrMsg(pQueryInfo->msg, msg11);
     }
 
     char name1[128] = {0};
@@ -4313,9 +4323,6 @@ int32_t setAlterTableInfo(SSqlObj* pSql, struct SSqlInfo* pInfo) {
     TAOS_FIELD f = tscCreateField(TSDB_DATA_TYPE_INT, name1, tDataTypeDesc[TSDB_DATA_TYPE_INT].nSize);
     tscFieldInfoAppend(&pQueryInfo->fieldsInfo, &f);
   } else if (pAlterSQL->type == TSDB_ALTER_TABLE_CHANGE_TAG_COLUMN) {
-    const char* msg1 = "tag name too long";
-    const char* msg2 = "invalid tag name";
-
     tVariantList* pVarList = pAlterSQL->varList;
     if (pVarList->nExpr > 2) {
       return TSDB_CODE_INVALID_SQL;
@@ -4325,11 +4332,11 @@ int32_t setAlterTableInfo(SSqlObj* pSql, struct SSqlInfo* pInfo) {
     tVariantListItem* pDstItem = &pAlterSQL->varList->a[1];
 
     if (pSrcItem->pVar.nLen >= TSDB_COL_NAME_LEN || pDstItem->pVar.nLen >= TSDB_COL_NAME_LEN) {
-      return invalidSqlErrMsg(pQueryInfo->msg, msg1);
+      return invalidSqlErrMsg(pQueryInfo->msg, msg9);
     }
 
     if (pSrcItem->pVar.nType != TSDB_DATA_TYPE_BINARY || pDstItem->pVar.nType != TSDB_DATA_TYPE_BINARY) {
-      return invalidSqlErrMsg(pQueryInfo->msg, msg2);
+      return invalidSqlErrMsg(pQueryInfo->msg, msg10);
     }
 
     SColumnIndex srcIndex = COLUMN_INDEX_INITIALIZER;
@@ -4355,10 +4362,6 @@ int32_t setAlterTableInfo(SSqlObj* pSql, struct SSqlInfo* pInfo) {
     f = tscCreateField(TSDB_DATA_TYPE_INT, name, tDataTypeDesc[TSDB_DATA_TYPE_INT].nSize);
     tscFieldInfoAppend(&pQueryInfo->fieldsInfo, &f);
   } else if (pAlterSQL->type == TSDB_ALTER_TABLE_UPDATE_TAG_VAL) {
-    const char* msg1 = "invalid tag value";
-    const char* msg2 = "update normal column not supported";
-    const char* msg3 = "tag value too long";
-
     // Note: update can only be applied to table not super table.
     // the following is handle display tags value for meters created according to super table
     tVariantList* pVarList = pAlterSQL->varList;
@@ -4371,19 +4374,19 @@ int32_t setAlterTableInfo(SSqlObj* pSql, struct SSqlInfo* pInfo) {
     }
 
     if (columnIndex.columnIndex < tscGetNumOfColumns(pTableMeta)) {
-      return invalidSqlErrMsg(pQueryInfo->msg, msg2);
+      return invalidSqlErrMsg(pQueryInfo->msg, msg12);
     }
 
     SSchema* pTagsSchema = tscGetTableColumnSchema(pTableMetaInfo->pTableMeta, columnIndex.columnIndex);
     if (tVariantDump(&pVarList->a[1].pVar, pAlterSQL->tagData.data /*pCmd->payload*/, pTagsSchema->type) !=
         TSDB_CODE_SUCCESS) {
-      return invalidSqlErrMsg(pQueryInfo->msg, msg1);
+      return invalidSqlErrMsg(pQueryInfo->msg, msg13);
     }
 
     // validate the length of binary
     if ((pTagsSchema->type == TSDB_DATA_TYPE_BINARY || pTagsSchema->type == TSDB_DATA_TYPE_NCHAR) &&
         pVarList->a[1].pVar.nLen > pTagsSchema->bytes) {
-      return invalidSqlErrMsg(pQueryInfo->msg, msg3);
+      return invalidSqlErrMsg(pQueryInfo->msg, msg14);
     }
 
     char name1[128] = {0};
@@ -4405,17 +4408,12 @@ int32_t setAlterTableInfo(SSqlObj* pSql, struct SSqlInfo* pInfo) {
   
     tscFieldInfoAppend(&pQueryInfo->fieldsInfo, &pFieldList->p[0]);
   } else if (pAlterSQL->type == TSDB_ALTER_TABLE_DROP_COLUMN) {
-    const char* msg1 = "no columns can be dropped";
-    const char* msg2 = "only support one column";
-    const char* msg4 = "illegal column name";
-    const char* msg3 = "primary timestamp column cannot be dropped";
-
     if (tscGetNumOfColumns(pTableMeta) == TSDB_MIN_COLUMNS) {  //
-      return invalidSqlErrMsg(tscGetErrorMsgPayload(pCmd), msg1);
+      return invalidSqlErrMsg(tscGetErrorMsgPayload(pCmd), msg15);
     }
 
     if (pAlterSQL->varList->nExpr > 1) {
-      return invalidSqlErrMsg(tscGetErrorMsgPayload(pCmd), msg2);
+      return invalidSqlErrMsg(tscGetErrorMsgPayload(pCmd), msg16);
     }
 
     tVariantListItem* pItem = &pAlterSQL->varList->a[0];
@@ -4423,11 +4421,11 @@ int32_t setAlterTableInfo(SSqlObj* pSql, struct SSqlInfo* pInfo) {
     SColumnIndex columnIndex = COLUMN_INDEX_INITIALIZER;
     SSQLToken    name = {.type = TK_STRING, .z = pItem->pVar.pz, .n = pItem->pVar.nLen};
     if (getColumnIndexByName(&name, pQueryInfo, &columnIndex) != TSDB_CODE_SUCCESS) {
-      return invalidSqlErrMsg(pQueryInfo->msg, msg4);
+      return invalidSqlErrMsg(pQueryInfo->msg, msg17);
     }
 
     if (columnIndex.columnIndex == PRIMARYKEY_TIMESTAMP_COL_INDEX) {
-      return invalidSqlErrMsg(pQueryInfo->msg, msg3);
+      return invalidSqlErrMsg(pQueryInfo->msg, msg18);
     }
 
     char name1[TSDB_COL_NAME_LEN + 1] = {0};
diff --git a/src/client/src/tscServer.c b/src/client/src/tscServer.c
index 80640ba54503aac259015c01ce020c8f2d55ec4d..0e5907f9928e9a67d96573a746ef815b930ca25a 100644
--- a/src/client/src/tscServer.c
+++ b/src/client/src/tscServer.c
@@ -502,7 +502,7 @@ void tscKillSTableQuery(SSqlObj *pSql) {
     }
   }
 
-  tscTrace("%p metric query is cancelled", pSql);
+  tscTrace("%p super table query cancelled", pSql);
 }
 
 int tscBuildRetrieveMsg(SSqlObj *pSql, SSqlInfo *pInfo) {
@@ -649,7 +649,7 @@ int tscBuildQueryMsg(SSqlObj *pSql, SSqlInfo *pInfo) {
     numOfTables = 1;
     tscSetDnodeIpList(pSql, pTableMeta);
     pQueryMsg->head.vgId = htonl(pTableMeta->vgroupInfo.vgId);
-    tscTrace("%p queried tables:%d, table id: %s", pSql, 1, pTableMetaInfo->name);
+    tscTrace("%p queried tables:%d, table name: %s", pSql, 1, pTableMetaInfo->name);
   } else {  // query super table
     int32_t index = pTableMetaInfo->vgroupIndex;
     if (index < 0) {
diff --git a/src/client/src/tscSql.c b/src/client/src/tscSql.c
index 5d2c32344f5a5cb5ebce5eeeefae678335f4c0f1..3b75739e5ebbfcb3c50f22f587cc71d2dea94eb2 100644
--- a/src/client/src/tscSql.c
+++ b/src/client/src/tscSql.c
@@ -270,7 +270,7 @@ int taos_query_imp(STscObj *pObj, SSqlObj *pSql) {
   }
 
   if (pRes->code != TSDB_CODE_SUCCESS) {
-    tscFreeSqlObjPartial(pSql);
+    tscPartiallyFreeSqlObj(pSql);
   }
 
   return pRes->code;
@@ -576,7 +576,7 @@ void taos_free_result_imp(TAOS_RES *res, int keepCmd) {
       if (keepCmd) {
         tscFreeSqlResult(pSql);
       } else {
-        tscFreeSqlObjPartial(pSql);
+        tscPartiallyFreeSqlObj(pSql);
       }
     }
     
@@ -586,7 +586,7 @@ void taos_free_result_imp(TAOS_RES *res, int keepCmd) {
   // set freeFlag to 1 in retrieve message if there are un-retrieved results
   SQueryInfo *pQueryInfo = tscGetQueryInfoDetail(&pSql->cmd, 0);
   if (pQueryInfo == NULL) {
-    tscFreeSqlObjPartial(pSql);
+    tscPartiallyFreeSqlObj(pSql);
     return;
   }
 
@@ -638,7 +638,7 @@ void taos_free_result_imp(TAOS_RES *res, int keepCmd) {
         tscFreeSqlResult(pSql);
         tscTrace("%p sql result is freed by app while sql command is kept", pSql);
       } else {
-        tscFreeSqlObjPartial(pSql);
+        tscPartiallyFreeSqlObj(pSql);
         tscTrace("%p sql result is freed by app", pSql);
       }
     } else {  // for async release, remove its link
@@ -659,7 +659,7 @@ void taos_free_result_imp(TAOS_RES *res, int keepCmd) {
         tscFreeSqlResult(pSql);
         tscTrace("%p sql result is freed while sql command is kept", pSql);
       } else {
-        tscFreeSqlObjPartial(pSql);
+        tscPartiallyFreeSqlObj(pSql);
         tscTrace("%p sql result is freed by app", pSql);
       }
     }
@@ -1004,7 +1004,7 @@ int taos_load_table_info(TAOS *taos, const char *tableNameList) {
 
   tscTrace("%p load multi metermeta result:%d %s pObj:%p", pSql, pRes->code, taos_errstr(taos), pObj);
   if (pRes->code != TSDB_CODE_SUCCESS) {
-    tscFreeSqlObjPartial(pSql);
+    tscPartiallyFreeSqlObj(pSql);
   }
 
   return pRes->code;
diff --git a/src/client/src/tscSubquery.c b/src/client/src/tscSubquery.c
index 10d25fa179e6b9545e9e1b544cf5543f97879698..d8a2fa366d9590a2bf313f7e70aa51e9ebac4b86 100644
--- a/src/client/src/tscSubquery.c
+++ b/src/client/src/tscSubquery.c
@@ -237,8 +237,8 @@ int32_t tscLaunchSecondPhaseSubqueries(SSqlObj* pSql) {
   SJoinSubquerySupporter* pSupporter = NULL;
   
   /*
-   * If the columns are not involved in the final select clause, the secondary query will not be launched
-   * for the subquery.
+   * If the columns are not involved in the final select clause,
+   * the corresponding query will not be issued.
    */
   SSubqueryState* pState = NULL;
   
@@ -269,7 +269,7 @@ int32_t tscLaunchSecondPhaseSubqueries(SSqlObj* pSql) {
     pSupporter = pPrevSub->param;
   
     if (taosArrayGetSize(pSupporter->exprList) == 0) {
-      tscTrace("%p subIndex: %d, not need to launch query, ignore it", pSql, i);
+      tscTrace("%p subIndex: %d, no need to launch query, ignore it", pSql, i);
     
       tscDestroyJoinSupporter(pSupporter);
       tscFreeSqlObj(pPrevSub);
@@ -314,15 +314,6 @@ int32_t tscLaunchSecondPhaseSubqueries(SSqlObj* pSql) {
     pSupporter->exprList = NULL;
     pSupporter->colList = NULL;
     memset(&pSupporter->fieldsInfo, 0, sizeof(SFieldInfo));
-    
-    /*
-     * if the first column of the secondary query is not ts function, add this function.
-     * Because this column is required to filter with timestamp after intersecting.
-     */
-//    SSqlExpr* pExpr = taosArrayGet(pQueryInfo->exprList, 0);
-//    if (pExpr->functionId != TSDB_FUNC_TS) {
-//      tscAddTimestampColumn(pQueryInfo, TSDB_FUNC_TS, 0);
-//    }
   
     SQueryInfo *pNewQueryInfo = tscGetQueryInfoDetail(&pNew->cmd, 0);
     assert(pNew->numOfSubs == 0 && pNew->cmd.numOfClause == 1 && pNewQueryInfo->numOfTables == 1);
@@ -348,8 +339,6 @@ int32_t tscLaunchSecondPhaseSubqueries(SSqlObj* pSql) {
       pExpr->numOfParams = 1;
     }
   
-    tscPrintSelectClause(pNew, 0);
-  
     size_t numOfCols = taosArrayGetSize(pNewQueryInfo->colList);
     tscTrace("%p subquery:%p tableIndex:%d, vgroupIndex:%d, type:%d, exprInfo:%d, colList:%d, fieldsInfo:%d, name:%s",
              pSql, pNew, 0, pTableMetaInfo->vgroupIndex, pNewQueryInfo->type,
@@ -917,7 +906,7 @@ int32_t tscLaunchJoinSubquery(SSqlObj *pSql, int16_t tableIndex, SJoinSubquerySu
   
     size_t numOfCols = taosArrayGetSize(pNewQueryInfo->colList);
   
-    tscTrace("%p subquery:%p tableIndex:%d, vnodeIdx:%d, type:%d, transfer to ts_comp query to retrieve timestamps, "
+    tscTrace("%p subquery:%p tableIndex:%d, vgroupIndex:%d, type:%d, transfer to ts_comp query to retrieve timestamps, "
              "exprInfo:%d, colList:%d, fieldsInfo:%d, name:%s",
              pSql, pNew, tableIndex, pTableMetaInfo->vgroupIndex, pNewQueryInfo->type,
              tscSqlExprNumOfExprs(pNewQueryInfo), numOfCols,
@@ -928,7 +917,6 @@ int32_t tscLaunchJoinSubquery(SSqlObj *pSql, int16_t tableIndex, SJoinSubquerySu
     pNewQueryInfo->type |= TSDB_QUERY_TYPE_SUBQUERY;
   }
 
-  tscPrintSelectClause(pNew, 0);
   return tscProcessSql(pNew);
 }
 
@@ -938,9 +926,9 @@ int32_t tscHandleMasterJoinQuery(SSqlObj* pSql) {
   assert((pQueryInfo->type & TSDB_QUERY_TYPE_SUBQUERY) == 0);
   
   SSubqueryState *pState = calloc(1, sizeof(SSubqueryState));
-  
   pState->numOfTotal = pQueryInfo->numOfTables;
   
+  tscTrace("%p start launched subquery, total:%d", pSql, pQueryInfo->numOfTables);
   for (int32_t i = 0; i < pQueryInfo->numOfTables; ++i) {
     SJoinSubquerySupporter *pSupporter = tscCreateJoinSupporter(pSql, pState, i);
     
diff --git a/src/client/src/tscUtil.c b/src/client/src/tscUtil.c
index c5b4d7423d992b7ad6336649688de8166794c004..3dab478cf7c57e06f798836633405a14fa48bc94 100644
--- a/src/client/src/tscUtil.c
+++ b/src/client/src/tscUtil.c
@@ -301,12 +301,10 @@ int32_t tscCreateResPointerInfo(SSqlRes* pRes, SQueryInfo* pQueryInfo) {
 }
 
 void tscDestroyResPointerInfo(SSqlRes* pRes) {
-  if (pRes->buffer != NULL) {
-    // free all buffers containing the multibyte string
+  if (pRes->buffer != NULL) { // free all buffers containing the multibyte string
     for (int i = 0; i < pRes->numOfCols; i++) {
       tfree(pRes->buffer[i]);
     }
-    
     pRes->numOfCols = 0;
   }
   
@@ -335,50 +333,15 @@ void tscResetSqlCmdObj(SSqlCmd* pCmd) {
   tscFreeQueryInfo(pCmd);
 }
 
-/*
- * this function must not change the pRes->code value, since it may be used later.
- */
-void tscFreeResData(SSqlObj* pSql) {
-  SSqlRes* pRes = &pSql->res;
-  
-  pRes->row = 0;
-  
-  pRes->rspType = 0;
-  pRes->rspLen = 0;
-  pRes->row = 0;
-  
-  pRes->numOfRows = 0;
-  pRes->numOfTotal = 0;
-  pRes->numOfTotalInCurrentClause = 0;
-  
-  pRes->numOfGroups = 0;
-  pRes->precision = 0;
-  pRes->qhandle = 0;
-  
-  pRes->offset = 0;
-  pRes->useconds = 0;
-  
+void tscFreeSqlResult(SSqlObj* pSql) {
   tscDestroyLocalReducer(pSql);
   
+  SSqlRes* pRes = &pSql->res;
   tscDestroyResPointerInfo(pRes);
+  memset(&pSql->res, 0, sizeof(SSqlRes));
 }
 
-void tscFreeSqlResult(SSqlObj* pSql) {
-  tfree(pSql->res.pRsp);
-  pSql->res.row = 0;
-  pSql->res.numOfRows = 0;
-  pSql->res.numOfTotal = 0;
-
-  pSql->res.numOfGroups = 0;
-  tfree(pSql->res.pGroupRec);
-
-  tscDestroyLocalReducer(pSql);
-
-  tscDestroyResPointerInfo(&pSql->res);
-  tfree(pSql->res.pColumnIndex);
-}
-
-void tscFreeSqlObjPartial(SSqlObj* pSql) {
+void tscPartiallyFreeSqlObj(SSqlObj* pSql) {
   if (pSql == NULL || pSql->signature != pSql) {
     return;
   }
@@ -412,7 +375,7 @@ void tscFreeSqlObj(SSqlObj* pSql) {
   if (pSql == NULL || pSql->signature != pSql) return;
 
   tscTrace("%p start to free sql object", pSql);
-  tscFreeSqlObjPartial(pSql);
+  tscPartiallyFreeSqlObj(pSql);
 
   pSql->signature = NULL;
   pSql->fp = NULL;
@@ -1897,7 +1860,7 @@ SSqlObj* createSubqueryObj(SSqlObj* pSql, int16_t tableIndex, void (*fp)(), void
     size_t size = taosArrayGetSize(pNewQueryInfo->colList);
     
     tscTrace(
-        "%p new subquery: %p, tableIndex:%d, vnodeIdx:%d, type:%d, exprInfo:%d, colList:%d,"
+        "%p new subquery:%p, tableIndex:%d, vgroupIndex:%d, type:%d, exprInfo:%d, colList:%d,"
         "fieldInfo:%d, name:%s, qrang:%" PRId64 " - %" PRId64 " order:%d, limit:%" PRId64,
         pSql, pNew, tableIndex, pTableMetaInfo->vgroupIndex, pNewQueryInfo->type, tscSqlExprNumOfExprs(pNewQueryInfo),
         size, pNewQueryInfo->fieldsInfo.numOfOutput, pFinalInfo->name, pNewQueryInfo->window.skey,
@@ -2107,7 +2070,7 @@ void tscTryQueryNextClause(SSqlObj* pSql, void (*queryFp)()) {
 
   //backup the total number of result first
   int64_t num = pRes->numOfTotal + pRes->numOfTotalInCurrentClause;
-  tscFreeResData(pSql);
+  tscFreeSqlResult(pSql);
   
   pRes->numOfTotal = num;