diff --git a/src/query/src/qExecutor.c b/src/query/src/qExecutor.c
index 8f565cd9c6..6bc55effdc 100644
--- a/src/query/src/qExecutor.c
+++ b/src/query/src/qExecutor.c
@@ -12,12 +12,10 @@
  * You should have received a copy of the GNU Affero General Public License
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  */
-#include <taosmsg.h>
 #include "os.h"
 #include "qfill.h"
 
 #include "hash.h"
-#include "hashfunc.h"
 #include "qExecutor.h"
 #include "qUtil.h"
 #include "qast.h"
@@ -25,7 +23,6 @@
 #include "query.h"
 #include "queryLog.h"
 #include "taosmsg.h"
-#include "tdataformat.h"
 #include "tlosertree.h"
 #include "tscUtil.h"  // todo move the function to common module
 #include "tscompression.h"
@@ -91,6 +88,9 @@ typedef struct {
 } SQueryStatusInfo;
 
 #define CLEAR_QUERY_STATUS(q, st)   ((q)->status &= (~(st)))
+#define GET_NUM_OF_TABLEGROUP(q)    taosArrayGetSize((q)->tableqinfoGroupInfo.pGroupList)
+#define GET_TABLEGROUP(q, _index)   ((SArray*) taosArrayGetP((q)->tableqinfoGroupInfo.pGroupList, (_index)))
+
 static void setQueryStatus(SQuery *pQuery, int8_t status);
 
 static bool isIntervalQuery(SQuery *pQuery) { return pQuery->intervalTime > 0; }
@@ -1708,7 +1708,23 @@ static bool onlyFirstQuery(SQuery *pQuery) { return onlyOneQueryType(pQuery, TSD
 
 static bool onlyLastQuery(SQuery *pQuery) { return onlyOneQueryType(pQuery, TSDB_FUNC_LAST, TSDB_FUNC_LAST_DST); }
 
-static void changeExecuteScanOrder(SQuery *pQuery, bool stableQuery) {
+// todo refactor, add iterator
+static void doExchangeTimeWindow(SQInfo* pQInfo) {
+  size_t t = GET_NUM_OF_TABLEGROUP(pQInfo);
+  for(int32_t i = 0; i < t; ++i) {
+    SArray* p1 = GET_TABLEGROUP(pQInfo, i);
+
+    size_t len = taosArrayGetSize(p1);
+    for(int32_t j = 0; j < len; ++j) {
+      STableQueryInfo* pTableQueryInfo = (STableQueryInfo*) taosArrayGetP(p1, j);
+      SWAP(pTableQueryInfo->win.skey, pTableQueryInfo->win.ekey, TSKEY);
+    }
+  }
+}
+
+static void changeExecuteScanOrder(SQInfo *pQInfo, bool stableQuery) {
+  SQuery* pQuery = pQInfo->runtimeEnv.pQuery;
+
   // in case of point-interpolation query, use asc order scan
   char msg[] = "QInfo:%p scan order changed for %s query, old:%d, new:%d, qrange exchanged, old qrange:%" PRId64
                "-%" PRId64 ", new qrange:%" PRId64 "-%" PRId64;
@@ -1748,6 +1764,7 @@ static void changeExecuteScanOrder(SQuery *pQuery, bool stableQuery) {
                pQuery->window.ekey, pQuery->window.ekey, pQuery->window.skey);
 
         SWAP(pQuery->window.skey, pQuery->window.ekey, TSKEY);
+        doExchangeTimeWindow(pQInfo);
       }
 
       pQuery->order.order = TSDB_ORDER_ASC;
@@ -1757,6 +1774,7 @@ static void changeExecuteScanOrder(SQuery *pQuery, bool stableQuery) {
                pQuery->window.ekey, pQuery->window.ekey, pQuery->window.skey);
 
         SWAP(pQuery->window.skey, pQuery->window.ekey, TSKEY);
+        doExchangeTimeWindow(pQInfo);
       }
 
       pQuery->order.order = TSDB_ORDER_DESC;
@@ -2489,10 +2507,10 @@ int32_t mergeIntoGroupResult(SQInfo *pQInfo) {
   int64_t st = taosGetTimestampMs();
   int32_t ret = TSDB_CODE_SUCCESS;
 
-  int32_t numOfGroups = taosArrayGetSize(pQInfo->tableqinfoGroupInfo.pGroupList);
+  int32_t numOfGroups = GET_NUM_OF_TABLEGROUP(pQInfo);
 
   while (pQInfo->groupIndex < numOfGroups) {
-    SArray *group = taosArrayGetP(pQInfo->tableqinfoGroupInfo.pGroupList, pQInfo->groupIndex);
+    SArray *group = GET_TABLEGROUP(pQInfo, pQInfo->groupIndex);
     ret = mergeIntoGroupResultImpl(pQInfo, group);
     if (ret < 0) {  // not enough disk space to save the data into disk
       return -1;
@@ -2525,7 +2543,7 @@ void copyResToQueryResultBuf(SQInfo *pQInfo, SQuery *pQuery) {
     }
 
     // check if all results has been sent to client
-    int32_t numOfGroup = taosArrayGetSize(pQInfo->tableqinfoGroupInfo.pGroupList);
+    int32_t numOfGroup = GET_NUM_OF_TABLEGROUP(pQInfo);
     if (pQInfo->numOfGroupResultPages == 0 && pQInfo->groupIndex == numOfGroup) {
       pQInfo->tableIndex = pQInfo->tableqinfoGroupInfo.numOfTables;  // set query completed
       return;
@@ -2859,10 +2877,10 @@ void disableFuncInReverseScan(SQInfo *pQInfo) {
     }
   }
   
-  int32_t numOfGroups = taosArrayGetSize(pQInfo->tableqinfoGroupInfo.pGroupList);
+  int32_t numOfGroups = GET_NUM_OF_TABLEGROUP(pQInfo);
   
   for(int32_t i = 0; i < numOfGroups; ++i) {
-    SArray *group = taosArrayGetP(pQInfo->tableqinfoGroupInfo.pGroupList, i);
+    SArray *group = GET_TABLEGROUP(pQInfo, i);
     
     size_t t = taosArrayGetSize(group);
     for (int32_t j = 0; j < t; ++j) {
@@ -3349,7 +3367,7 @@ void setWindowResOutputBufInitCtx(SQueryRuntimeEnv *pRuntimeEnv, SWindowResult *
     SQLFunctionCtx *pCtx = &pRuntimeEnv->pCtx[i];
 
     pCtx->resultInfo = &pResult->resultInfo[i];
-    if (pCtx->resultInfo->complete) {
+    if (pCtx->resultInfo->initialized && pCtx->resultInfo->complete) {
       continue;
     }
 
@@ -3479,7 +3497,7 @@ static int32_t getNumOfSubset(SQInfo *pQInfo) {
   if (isGroupbyNormalCol(pQuery->pGroupbyExpr) || (isIntervalQuery(pQuery))) {
     totalSubset = numOfClosedTimeWindow(&pQInfo->runtimeEnv.windowResInfo);
   } else {
-    totalSubset = taosArrayGetSize(pQInfo->tableqinfoGroupInfo.pGroupList);
+    totalSubset = GET_NUM_OF_TABLEGROUP(pQInfo);
   }
 
   return totalSubset;
@@ -3619,36 +3637,40 @@ void stableApplyFunctionsOnBlock(SQueryRuntimeEnv *pRuntimeEnv, SDataBlockInfo *
 bool queryHasRemainResults(SQueryRuntimeEnv* pRuntimeEnv) {
   SQuery *pQuery = pRuntimeEnv->pQuery;
   SFillInfo *pFillInfo = pRuntimeEnv->pFillInfo;
-  
-  // todo refactor
-  if (pQuery->fillType == TSDB_FILL_NONE || (pQuery->fillType != TSDB_FILL_NONE && isPointInterpoQuery(pQuery))) {
-    assert(pFillInfo == NULL);
+
+  if (pQuery->limit.limit > 0 && pQuery->rec.total >= pQuery->limit.limit) {
     return false;
   }
 
-  if (pQuery->limit.limit > 0 && pQuery->rec.rows >= pQuery->limit.limit) {
-    return false;
-  }
+  if (pQuery->fillType != TSDB_FILL_NONE && !isPointInterpoQuery(pQuery)) {
+    // There are results not returned to client yet, so filling operation applied to the remain result is required
+    // in the first place.
+    int32_t remain = taosNumOfRemainRows(pFillInfo);
+    if (remain > 0) {
+      return true;
+    }
 
-  // There are results not returned to client, fill operation applied to the remain result set in the
-  // first place is required.
-  int32_t remain = taosNumOfRemainRows(pFillInfo);
-  if (remain > 0) {
-    return true;
-  }
-  
-  /*
-   * While the code reaches here, there are no results returned to client now.
-   * If query is not completed yet, the gaps between two results blocks need to be handled after next data block
-   * is retrieved from TSDB.
-   *
-   * NOTE: If the result set is not the first block, the gap in front of the result set will be filled. If the result
-   * set is the FIRST result block, the gap between the start time of query time window and the timestamp of the
-   * first result row in the actual result set will fill nothing.
-   */
-  if (Q_STATUS_EQUAL(pQuery->status, QUERY_COMPLETED)) {
-    int32_t numOfTotal = getFilledNumOfRes(pFillInfo, pQuery->window.ekey, pQuery->rec.capacity);
-    return numOfTotal > 0;
+    /*
+     * While the code reaches here, there are no results remains now.
+     * If query is not completed yet, the gaps between two results blocks need to be handled after next data block
+     * is retrieved from TSDB.
+     *
+     * NOTE: If the result set is not the first block, the gap in front of the result set will be filled. If the result
+     * set is the FIRST result block, the gap between the start time of query time window and the timestamp of the
+     * first result row in the actual result set will fill nothing.
+     */
+    if (Q_STATUS_EQUAL(pQuery->status, QUERY_COMPLETED)) {
+      int32_t numOfTotal = getFilledNumOfRes(pFillInfo, pQuery->window.ekey, pQuery->rec.capacity);
+      return numOfTotal > 0;
+    }
+
+  } else {
+    // there are results waiting for returned to client.
+    if (Q_STATUS_EQUAL(pQuery->status, QUERY_COMPLETED) &&
+        (isGroupbyNormalCol(pQuery->pGroupbyExpr) || isIntervalQuery(pQuery)) &&
+        (pRuntimeEnv->windowResInfo.size > 0)) {
+      return true;
+    }
   }
 
   return false;
@@ -3690,7 +3712,7 @@ static void doCopyQueryResultToMsg(SQInfo *pQInfo, int32_t numOfRows, char *data
   }
 }
 
-int32_t doFillGapsInResults(SQueryRuntimeEnv* pRuntimeEnv, tFilePage **pDst, int32_t *numOfInterpo) {
+int32_t doFillGapsInResults(SQueryRuntimeEnv* pRuntimeEnv, tFilePage **pDst, int32_t *numOfFilled) {
   SQInfo* pQInfo = GET_QINFO_ADDR(pRuntimeEnv);
   SQuery *pQuery = pRuntimeEnv->pQuery;
   SFillInfo* pFillInfo = pRuntimeEnv->pFillInfo;
@@ -3995,7 +4017,7 @@ static void setupQueryHandle(void* tsdb, SQInfo* pQInfo, bool isSTableQuery) {
     && (!isGroupbyNormalCol(pQuery->pGroupbyExpr))
     && (!isFixedOutputQuery(pQuery))
   ) {
-    SArray* pa = taosArrayGetP(pQInfo->tableqinfoGroupInfo.pGroupList, 0);
+    SArray* pa = GET_TABLEGROUP(pQInfo, 0);
     STableQueryInfo* pCheckInfo = taosArrayGetP(pa, 0);
     cond.twindow = pCheckInfo->win;
   }
@@ -4039,7 +4061,7 @@ int32_t doInitQInfo(SQInfo *pQInfo, void *param, void *tsdb, int32_t vgId, bool
   pQuery->precision = tsdbGetCfg(tsdb)->precision;
 
   setScanLimitationByResultBuffer(pQuery);
-  changeExecuteScanOrder(pQuery, false);
+  changeExecuteScanOrder(pQInfo, false);
   setupQueryHandle(tsdb, pQInfo, isSTableQuery);
   
   pQInfo->tsdb = tsdb;
@@ -4142,9 +4164,9 @@ static int64_t scanMultiTableDataBlocks(SQInfo *pQInfo) {
     STableQueryInfo *pTableQueryInfo = NULL;
 
     // todo opt performance using hash table
-    size_t numOfGroup = taosArrayGetSize(pQInfo->tableqinfoGroupInfo.pGroupList);
+    size_t numOfGroup = GET_NUM_OF_TABLEGROUP(pQInfo);
     for (int32_t i = 0; i < numOfGroup; ++i) {
-      SArray *group = taosArrayGetP(pQInfo->tableqinfoGroupInfo.pGroupList, i);
+      SArray *group = GET_TABLEGROUP(pQInfo, i);
 
       size_t num = taosArrayGetSize(group);
       for (int32_t j = 0; j < num; ++j) {
@@ -4197,7 +4219,7 @@ static bool multiTableMultioutputHelper(SQInfo *pQInfo, int32_t index) {
   SQuery *          pQuery = pRuntimeEnv->pQuery;
 
   setQueryStatus(pQuery, QUERY_NOT_COMPLETED);
-  SArray *group = taosArrayGetP(pQInfo->tableqinfoGroupInfo.pGroupList, 0);
+  SArray *group = GET_TABLEGROUP(pQInfo, 0);
   STableQueryInfo* pCheckInfo = taosArrayGetP(group, index);
 
   setTagVal(pRuntimeEnv, pCheckInfo->pTable, pQInfo->tsdb);
@@ -4261,7 +4283,7 @@ static void sequentialTableProcess(SQInfo *pQInfo) {
   SQuery *          pQuery = pRuntimeEnv->pQuery;
   setQueryStatus(pQuery, QUERY_COMPLETED);
 
-  size_t numOfGroups = taosArrayGetSize(pQInfo->tableqinfoGroupInfo.pGroupList);
+  size_t numOfGroups = GET_NUM_OF_TABLEGROUP(pQInfo);
 
   if (isPointInterpoQuery(pQuery) || isFirstLastRowQuery(pQuery)) {
     resetCtxOutputBuf(pRuntimeEnv);
@@ -4311,7 +4333,7 @@ static void sequentialTableProcess(SQInfo *pQInfo) {
       taosArrayDestroy(s);
 
       // here we simply set the first table as current table
-      pQuery->current = (STableQueryInfo*) taosArrayGetP(pQInfo->tableqinfoGroupInfo.pGroupList, 0);
+      pQuery->current = (STableQueryInfo*) GET_TABLEGROUP(pQInfo, 0);
       scanOneTableDataBlocks(pRuntimeEnv, pQuery->current->lastKey);
       
       int64_t numOfRes = getNumOfResult(pRuntimeEnv);
@@ -4424,7 +4446,7 @@ static void sequentialTableProcess(SQInfo *pQInfo) {
     resetCtxOutputBuf(pRuntimeEnv);
     resetTimeWindowInfo(pRuntimeEnv, &pRuntimeEnv->windowResInfo);
 
-    SArray *group = taosArrayGetP(pQInfo->tableqinfoGroupInfo.pGroupList, 0);
+    SArray *group = GET_TABLEGROUP(pQInfo, 0);
     assert(taosArrayGetSize(group) == pQInfo->tableqinfoGroupInfo.numOfTables &&
            1 == taosArrayGetSize(pQInfo->tableqinfoGroupInfo.pGroupList));
 
@@ -4575,9 +4597,9 @@ static void doCloseAllTimeWindowAfterScan(SQInfo *pQInfo) {
   SQuery *pQuery = pQInfo->runtimeEnv.pQuery;
 
   if (isIntervalQuery(pQuery)) {
-    size_t numOfGroup = taosArrayGetSize(pQInfo->tableqinfoGroupInfo.pGroupList);
+    size_t numOfGroup = GET_NUM_OF_TABLEGROUP(pQInfo);
     for (int32_t i = 0; i < numOfGroup; ++i) {
-      SArray *group = taosArrayGetP(pQInfo->tableqinfoGroupInfo.pGroupList, i);
+      SArray *group = GET_TABLEGROUP(pQInfo, i);
 
       size_t num = taosArrayGetSize(group);
       for (int32_t j = 0; j < num; ++j) {
@@ -4794,7 +4816,7 @@ static void tableIntervalProcess(SQInfo *pQInfo, STableQueryInfo* pTableInfo) {
   SQuery *pQuery = pRuntimeEnv->pQuery;
   pQuery->current = pTableInfo;
 
-  int32_t numOfInterpo = 0;
+  int32_t numOfFilled = 0;
   TSKEY newStartKey = TSKEY_INITIAL_VAL;
   
   // skip blocks without load the actual data block from file if no filter condition present
@@ -4822,9 +4844,9 @@ static void tableIntervalProcess(SQInfo *pQInfo, STableQueryInfo* pTableInfo) {
     } else {
       taosFillSetStartInfo(pRuntimeEnv->pFillInfo, pQuery->rec.rows, pQuery->window.ekey);
       taosFillCopyInputDataFromFilePage(pRuntimeEnv->pFillInfo, (tFilePage**) pQuery->sdata);
-      numOfInterpo = 0;
+      numOfFilled = 0;
       
-      pQuery->rec.rows = doFillGapsInResults(pRuntimeEnv, (tFilePage **)pQuery->sdata, &numOfInterpo);
+      pQuery->rec.rows = doFillGapsInResults(pRuntimeEnv, (tFilePage **)pQuery->sdata, &numOfFilled);
       if (pQuery->rec.rows > 0 || Q_STATUS_EQUAL(pQuery->status, QUERY_COMPLETED)) {
         limitResults(pRuntimeEnv);
         break;
@@ -4843,7 +4865,7 @@ static void tableIntervalProcess(SQInfo *pQInfo, STableQueryInfo* pTableInfo) {
     clearFirstNTimeWindow(pRuntimeEnv, pQInfo->groupIndex);
   }
 
-  pQInfo->pointsInterpo += numOfInterpo;
+  pQInfo->pointsInterpo += numOfFilled;
 }
 
 static void tableQueryImpl(SQInfo *pQInfo) {
@@ -4851,45 +4873,41 @@ static void tableQueryImpl(SQInfo *pQInfo) {
   SQuery *          pQuery = pRuntimeEnv->pQuery;
 
   if (queryHasRemainResults(pRuntimeEnv)) {
-    /*
-     * There are remain results that are not returned due to result interpolation
-     * So, we do keep in this procedure instead of launching retrieve procedure for next results.
-     */
-    int32_t numOfInterpo = 0;
-    pQuery->rec.rows = doFillGapsInResults(pRuntimeEnv, (tFilePage **)pQuery->sdata, &numOfInterpo);
-  
-    if (pQuery->rec.rows > 0) {
-      limitResults(pRuntimeEnv);
-    }
-    
-    qDebug("QInfo:%p current:%" PRId64 " returned, total:%" PRId64, pQInfo, pQuery->rec.rows, pQuery->rec.total);
-    return;
-  }
 
-  // here we have scan all qualified data in both data file and cache
-  if (Q_STATUS_EQUAL(pQuery->status, QUERY_COMPLETED)) {
-    // continue to get push data from the group result
-    if (isGroupbyNormalCol(pQuery->pGroupbyExpr) ||
-        ((isIntervalQuery(pQuery) && pQuery->rec.total < pQuery->limit.limit))) {
-      // todo limit the output for interval query?
+    if (pQuery->fillType != TSDB_FILL_NONE) {
+      /*
+       * There are remain results that are not returned due to result interpolation
+       * So, we do keep in this procedure instead of launching retrieve procedure for next results.
+       */
+      int32_t numOfFilled = 0;
+      pQuery->rec.rows = doFillGapsInResults(pRuntimeEnv, (tFilePage **)pQuery->sdata, &numOfFilled);
+
+      if (pQuery->rec.rows > 0) {
+        limitResults(pRuntimeEnv);
+      }
+
+      qDebug("QInfo:%p current:%" PRId64 " returned, total:%" PRId64, pQInfo, pQuery->rec.rows, pQuery->rec.total);
+      return;
+    } else {
       pQuery->rec.rows = 0;
       pQInfo->groupIndex = 0;  // always start from 0
 
       if (pRuntimeEnv->windowResInfo.size > 0) {
         copyFromWindowResToSData(pQInfo, pRuntimeEnv->windowResInfo.pResult);
-        pQuery->rec.rows += pQuery->rec.rows;
-
         clearFirstNTimeWindow(pRuntimeEnv, pQInfo->groupIndex);
 
         if (pQuery->rec.rows > 0) {
           qDebug("QInfo:%p %"PRId64" rows returned from group results, total:%"PRId64"", pQInfo, pQuery->rec.rows, pQuery->rec.total);
+
+          // there are not data remains
+          if (pRuntimeEnv->windowResInfo.size <= 0) {
+            qDebug("QInfo:%p query over, %"PRId64" rows are returned", pQInfo, pQuery->rec.total);
+          }
+
           return;
         }
       }
     }
-
-    qDebug("QInfo:%p query over, %"PRId64" rows are returned", pQInfo, pQuery->rec.total);
-    return;
   }
 
   // number of points returned during this query
@@ -4897,7 +4915,7 @@ static void tableQueryImpl(SQInfo *pQInfo) {
   int64_t st = taosGetTimestampUs();
   
   assert(pQInfo->tableqinfoGroupInfo.numOfTables == 1);
-  SArray* g = taosArrayGetP(pQInfo->tableqinfoGroupInfo.pGroupList, 0);
+  SArray* g = GET_TABLEGROUP(pQInfo, 0);
   STableQueryInfo* item = taosArrayGetP(g, 0);
   
   // group by normal column, sliding window query, interval query are handled by interval query processor
@@ -5658,26 +5676,6 @@ static SQInfo *createQInfoImpl(SQueryTableMsg *pQueryMsg, SArray* pTableIdList,
   return pQInfo;
 
 _cleanup:
-  //tfree(pQuery->fillVal);
-
-  //if (pQuery->sdata != NULL) {
-  //  for (int16_t col = 0; col < pQuery->numOfOutput; ++col) {
-  //    tfree(pQuery->sdata[col]);
-  //  }
-  //}
-
-  //
-  //tfree(pQuery->sdata);
-  //tfree(pQuery->pFilterInfo);
-  //tfree(pQuery->colList);
-
-  //tfree(pExprs);
-  //tfree(pGroupbyExpr);
-
-  //taosArrayDestroy(pQInfo->arrTableIdInfo);
-  //tsdbDestoryTableGroup(&pQInfo->tableGroupInfo);
-  // 
-  //tfree(pQInfo);
   freeQInfo(pQInfo);
 
   return NULL;
@@ -5712,7 +5710,6 @@ static int32_t initQInfo(SQueryTableMsg *pQueryMsg, void *tsdb, int32_t vgId, SQ
     UNUSED(ret);
   }
 
-  // only the successful complete requries the sem_post/over = 1 operations.
   if ((QUERY_IS_ASC_QUERY(pQuery) && (pQuery->window.skey > pQuery->window.ekey)) ||
       (!QUERY_IS_ASC_QUERY(pQuery) && (pQuery->window.ekey > pQuery->window.skey))) {
     qDebug("QInfo:%p no result in time range %" PRId64 "-%" PRId64 ", order %d", pQInfo, pQuery->window.skey,
@@ -5722,7 +5719,7 @@ static int32_t initQInfo(SQueryTableMsg *pQueryMsg, void *tsdb, int32_t vgId, SQ
     sem_post(&pQInfo->dataReady);
     return TSDB_CODE_SUCCESS;
   }
-  
+
   if (pQInfo->tableqinfoGroupInfo.numOfTables == 0) {
     qDebug("QInfo:%p no table qualified for tag filter, abort query", pQInfo);
     setQueryStatus(pQuery, QUERY_COMPLETED);
@@ -5784,9 +5781,9 @@ static void freeQInfo(SQInfo *pQInfo) {
   }
 
   // todo refactor, extract method to destroytableDataInfo
-  int32_t numOfGroups = taosArrayGetSize(pQInfo->tableqinfoGroupInfo.pGroupList);
+  int32_t numOfGroups = GET_NUM_OF_TABLEGROUP(pQInfo);
   for (int32_t i = 0; i < numOfGroups; ++i) {
-    SArray *p = taosArrayGetP(pQInfo->tableqinfoGroupInfo.pGroupList, i);
+    SArray *p = GET_TABLEGROUP(pQInfo, i);;
 
     size_t num = taosArrayGetSize(p);
     for(int32_t j = 0; j < num; ++j) {
@@ -6053,6 +6050,11 @@ void qTableQuery(qinfo_t qinfo, void (*fp)(void*), void* param) {
     return;
   }
 
+  if (pQInfo->tableqinfoGroupInfo.numOfTables == 0) {
+    qDebug("QInfo:%p no table exists for query, abort", pQInfo);
+    return;
+  }
+
   qDebug("QInfo:%p query task is launched", pQInfo);
 
   if (onlyQueryTags(pQInfo->runtimeEnv.pQuery)) {
@@ -6175,14 +6177,14 @@ static void buildTagQueryResult(SQInfo* pQInfo) {
   SQueryRuntimeEnv *pRuntimeEnv = &pQInfo->runtimeEnv;
   SQuery *          pQuery = pRuntimeEnv->pQuery;
 
-  size_t numOfGroup = taosArrayGetSize(pQInfo->tableqinfoGroupInfo.pGroupList);
+  size_t numOfGroup = GET_NUM_OF_TABLEGROUP(pQInfo);
   assert(numOfGroup == 0 || numOfGroup == 1);
 
   if (numOfGroup == 0) {
     return;
   }
   
-  SArray* pa = taosArrayGetP(pQInfo->tableqinfoGroupInfo.pGroupList, 0);
+  SArray* pa = GET_TABLEGROUP(pQInfo, 0);
 
   size_t num = taosArrayGetSize(pa);
   assert(num == pQInfo->tableqinfoGroupInfo.numOfTables);
diff --git a/src/query/src/qUtil.c b/src/query/src/qUtil.c
index 622ec78ade..d7725f561d 100644
--- a/src/query/src/qUtil.c
+++ b/src/query/src/qUtil.c
@@ -133,7 +133,6 @@ void clearFirstNTimeWindow(SQueryRuntimeEnv *pRuntimeEnv, int32_t num) {
   }
   
   pWindowResInfo->size = remain;
-  printf("---------------size:%ld\n", taosHashGetSize(pWindowResInfo->hashList));
   for (int32_t k = 0; k < pWindowResInfo->size; ++k) {
     SWindowResult *pResult = &pWindowResInfo->pResult[k];
     int32_t *p = (int32_t *)taosHashGet(pWindowResInfo->hashList, (const char *)&pResult->window.skey,
diff --git a/src/tsdb/src/tsdbRWHelper.c b/src/tsdb/src/tsdbRWHelper.c
index 2338df1f97..41725433eb 100644
--- a/src/tsdb/src/tsdbRWHelper.c
+++ b/src/tsdb/src/tsdbRWHelper.c
@@ -121,7 +121,7 @@ int tsdbSetAndOpenHelperFile(SRWHelper *pHelper, SFileGroup *pGroup) {
     if (tsendfile(pHelper->files.nHeadF.fd, pHelper->files.headF.fd, NULL, TSDB_FILE_HEAD_SIZE) < TSDB_FILE_HEAD_SIZE) {
       tsdbError("vgId:%d failed to sendfile %d bytes from file %s to %s since %s", REPO_ID(pHelper->pRepo),
                 TSDB_FILE_HEAD_SIZE, pHelper->files.headF.fname, pHelper->files.nHeadF.fname, strerror(errno));
-      errno = TAOS_SYSTEM_ERROR(errno);
+      terrno = TAOS_SYSTEM_ERROR(errno);
       goto _err;
     }
 
@@ -144,7 +144,7 @@ int tsdbSetAndOpenHelperFile(SRWHelper *pHelper, SFileGroup *pGroup) {
   return tsdbLoadCompIdx(pHelper, NULL);
 
 _err:
-  return -1;
+  return terrno;
 }
 
 int tsdbCloseHelperFile(SRWHelper *pHelper, bool hasError) {
diff --git a/src/tsdb/src/tsdbRead.c b/src/tsdb/src/tsdbRead.c
index 716a2b0fee..41217f0f4f 100644
--- a/src/tsdb/src/tsdbRead.c
+++ b/src/tsdb/src/tsdbRead.c
@@ -148,7 +148,7 @@ TsdbQueryHandleT* tsdbQueryTables(TSDB_REPO_T* tsdb, STsdbQueryCond* pCond, STab
   pQueryHandle->type        = TSDB_QUERY_TYPE_ALL;
   pQueryHandle->cur.fid     = -1;
   pQueryHandle->cur.win     = TSWINDOW_INITIALIZER;
-  pQueryHandle->checkFiles  = true;//ASCENDING_TRAVERSE(pQueryHandle->order);
+  pQueryHandle->checkFiles  = true;
   pQueryHandle->activeIndex = 0;   // current active table index
   pQueryHandle->qinfo       = qinfo;
   pQueryHandle->outputCapacity = ((STsdbRepo*)tsdb)->config.maxRowsPerFileBlock;
@@ -475,11 +475,15 @@ static int32_t binarySearchForBlock(SCompBlock* pBlock, int32_t numOfBlocks, TSK
 }
 
 static int32_t getFileCompInfo(STsdbQueryHandle* pQueryHandle, int32_t* numOfBlocks, int32_t type) {
-  // todo check open file failed
   SFileGroup* fileGroup = pQueryHandle->pFileGroup;
-  
   assert(fileGroup->files[TSDB_FILE_TYPE_HEAD].fname > 0);
-  tsdbSetAndOpenHelperFile(&pQueryHandle->rhelper, fileGroup);
+
+  int32_t code = tsdbSetAndOpenHelperFile(&pQueryHandle->rhelper, fileGroup);
+
+  //open file failed, return error code to client
+  if (code != TSDB_CODE_SUCCESS) {
+    return code;
+  }
 
   // load all the comp offset value for all tables in this file
   *numOfBlocks = 0;
@@ -593,8 +597,7 @@ static bool doLoadFileDataBlock(STsdbQueryHandle* pQueryHandle, SCompBlock* pBlo
   if (pCheckInfo->pDataCols == NULL) {
     STsdbMeta* pMeta = tsdbGetMeta(pRepo);
     // TODO
-    pCheckInfo->pDataCols =
-        tdNewDataCols(pMeta->maxRowBytes, pMeta->maxCols, pRepo->config.maxRowsPerFileBlock);
+    pCheckInfo->pDataCols = tdNewDataCols(pMeta->maxRowBytes, pMeta->maxCols, pRepo->config.maxRowsPerFileBlock);
   }
 
   tdInitDataCols(pCheckInfo->pDataCols, tsdbGetTableSchema(pCheckInfo->pTableObj));
@@ -1359,16 +1362,18 @@ static int32_t createDataBlocksInfo(STsdbQueryHandle* pQueryHandle, int32_t numO
 }
 
 // todo opt for only one table case
-static bool getDataBlocksInFilesImpl(STsdbQueryHandle* pQueryHandle) {
+static int32_t getDataBlocksInFilesImpl(STsdbQueryHandle* pQueryHandle, bool* exists) {
   pQueryHandle->numOfBlocks = 0;
   SQueryFilePos* cur = &pQueryHandle->cur;
-  
+
+  int32_t code = TSDB_CODE_SUCCESS;
+
   int32_t numOfBlocks = 0;
   int32_t numOfTables = taosArrayGetSize(pQueryHandle->pTableCheckInfo);
   
   while ((pQueryHandle->pFileGroup = tsdbGetFileGroupNext(&pQueryHandle->fileIter)) != NULL) {
     int32_t type = ASCENDING_TRAVERSE(pQueryHandle->order)? QUERY_RANGE_GREATER_EQUAL:QUERY_RANGE_LESS_EQUAL;
-    if (getFileCompInfo(pQueryHandle, &numOfBlocks, type) != TSDB_CODE_SUCCESS) {
+    if ((code = getFileCompInfo(pQueryHandle, &numOfBlocks, type)) != TSDB_CODE_SUCCESS) {
       break;
     }
     
@@ -1393,20 +1398,25 @@ static bool getDataBlocksInFilesImpl(STsdbQueryHandle* pQueryHandle) {
   
   // no data in file anymore
   if (pQueryHandle->numOfBlocks <= 0) {
-    assert(pQueryHandle->pFileGroup == NULL);
+    if (code == TSDB_CODE_SUCCESS) {
+      assert(pQueryHandle->pFileGroup == NULL);
+    }
+
     cur->fid = -1;  // denote that there are no data in file anymore
-    
-    return false;
+    *exists = false;
+    return code;
   }
   
   cur->slot = ASCENDING_TRAVERSE(pQueryHandle->order)? 0:pQueryHandle->numOfBlocks-1;
   cur->fid = pQueryHandle->pFileGroup->fileId;
   
   STableBlockInfo* pBlockInfo = &pQueryHandle->pDataBlockInfo[cur->slot];
-  return loadFileDataBlock(pQueryHandle, pBlockInfo->compBlock, pBlockInfo->pTableCheckInfo);
+  *exists = loadFileDataBlock(pQueryHandle, pBlockInfo->compBlock, pBlockInfo->pTableCheckInfo);
+
+  return TSDB_CODE_SUCCESS;
 }
 
-static bool getDataBlocksInFiles(STsdbQueryHandle* pQueryHandle) {
+static int32_t getDataBlocksInFiles(STsdbQueryHandle* pQueryHandle, bool* exists) {
   STsdbFileH*    pFileHandle = tsdbGetFile(pQueryHandle->pTsdb);
   SQueryFilePos* cur = &pQueryHandle->cur;
 
@@ -1419,7 +1429,7 @@ static bool getDataBlocksInFiles(STsdbQueryHandle* pQueryHandle) {
     tsdbInitFileGroupIter(pFileHandle, &pQueryHandle->fileIter, pQueryHandle->order);
     tsdbSeekFileGroupIter(&pQueryHandle->fileIter, fid);
 
-    return getDataBlocksInFilesImpl(pQueryHandle);
+    return getDataBlocksInFilesImpl(pQueryHandle, exists);
   } else {
     // check if current file block is all consumed
     STableBlockInfo* pBlockInfo = &pQueryHandle->pDataBlockInfo[cur->slot];
@@ -1430,7 +1440,7 @@ static bool getDataBlocksInFiles(STsdbQueryHandle* pQueryHandle) {
       if ((cur->slot == pQueryHandle->numOfBlocks - 1 && ASCENDING_TRAVERSE(pQueryHandle->order)) ||
           (cur->slot == 0 && !ASCENDING_TRAVERSE(pQueryHandle->order))) {
         // all data blocks in current file has been checked already, try next file if exists
-        return getDataBlocksInFilesImpl(pQueryHandle);
+        return getDataBlocksInFilesImpl(pQueryHandle, exists);
       } else {
         // next block of the same file
         int32_t step = ASCENDING_TRAVERSE(pQueryHandle->order) ? 1 : -1;
@@ -1440,11 +1450,15 @@ static bool getDataBlocksInFiles(STsdbQueryHandle* pQueryHandle) {
         cur->blockCompleted = false;
         
         STableBlockInfo* pNext = &pQueryHandle->pDataBlockInfo[cur->slot];
-        return loadFileDataBlock(pQueryHandle, pNext->compBlock, pNext->pTableCheckInfo);
+        *exists = loadFileDataBlock(pQueryHandle, pNext->compBlock, pNext->pTableCheckInfo);
+
+        return TSDB_CODE_SUCCESS;
       }
     } else {
       handleDataMergeIfNeeded(pQueryHandle, pBlockInfo->compBlock, pCheckInfo);
-      return pQueryHandle->realNumOfRows > 0;
+      *exists = pQueryHandle->realNumOfRows > 0;
+
+      return TSDB_CODE_SUCCESS;
     }
   }
 }
@@ -1576,8 +1590,14 @@ bool tsdbNextDataBlock(TsdbQueryHandleT* pHandle) {
   }
   
   if (pQueryHandle->checkFiles) {
-    if (getDataBlocksInFiles(pQueryHandle)) {
-      return true;
+    bool exists = true;
+    int32_t code = getDataBlocksInFiles(pQueryHandle, &exists);
+    if (code != TSDB_CODE_SUCCESS) {
+      return false;
+    }
+
+    if (exists) {
+      return exists;
     }
   
     pQueryHandle->activeIndex = 0;