diff --git a/source/dnode/vnode/src/tsdb/tsdbRead.c b/source/dnode/vnode/src/tsdb/tsdbRead.c
index 927babc26c..65bc6a9cc1 100644
--- a/source/dnode/vnode/src/tsdb/tsdbRead.c
+++ b/source/dnode/vnode/src/tsdb/tsdbRead.c
@@ -1271,7 +1271,6 @@ _error:
 static int32_t getEndPosInDataBlock(STsdbReadHandle* pTsdbReadHandle, SDataBlockInfo* pBlockInfo);
 static int32_t doCopyRowsFromFileBlock(STsdbReadHandle* pTsdbReadHandle, int32_t capacity, int32_t numOfRows,
                                        int32_t start, int32_t end);
-static void    moveDataToFront(STsdbReadHandle* pTsdbReadHandle, int32_t numOfRows, int32_t numOfCols);
 static void    doCheckGeneratedBlockRange(STsdbReadHandle* pTsdbReadHandle);
 static void    copyAllRemainRowsFromFileBlock(STsdbReadHandle* pTsdbReadHandle, STableCheckInfo* pCheckInfo,
                                               SDataBlockInfo* pBlockInfo, int32_t endPos);
@@ -1301,7 +1300,7 @@ static int32_t handleDataMergeIfNeeded(STsdbReadHandle* pTsdbReadHandle, SBlock*
     if ((ascScan && (key != TSKEY_INITIAL_VAL && key < binfo.window.skey)) ||
         (!ascScan && (key != TSKEY_INITIAL_VAL && key > binfo.window.ekey))) {
       // do not load file block into buffer
-      int32_t step = ASCENDING_TRAVERSE(pTsdbReadHandle->order) ? 1 : -1;
+      int32_t step = ascScan ? 1 : -1;
 
       TSKEY maxKey =
           ASCENDING_TRAVERSE(pTsdbReadHandle->order) ? (binfo.window.skey - step) : (binfo.window.ekey - step);
@@ -1790,22 +1789,6 @@ static int32_t mergeTwoRowFromMem(STsdbReadHandle* pTsdbReadHandle, int32_t capa
 #endif
 }
 
-static void moveDataToFront(STsdbReadHandle* pTsdbReadHandle, int32_t numOfRows, int32_t numOfCols) {
-  if (numOfRows == 0 || ASCENDING_TRAVERSE(pTsdbReadHandle->order)) {
-    return;
-  }
-
-  // if the buffer is not full in case of descending order query, move the data in the front of the buffer
-  if (numOfRows < pTsdbReadHandle->outputCapacity) {
-    int32_t emptySize = pTsdbReadHandle->outputCapacity - numOfRows;
-    for (int32_t i = 0; i < numOfCols; ++i) {
-      SColumnInfoData* pColInfo = taosArrayGet(pTsdbReadHandle->pColumns, i);
-      memmove((char*)pColInfo->pData, (char*)pColInfo->pData + emptySize * pColInfo->info.bytes,
-              numOfRows * pColInfo->info.bytes);
-    }
-  }
-}
-
 static void getQualifiedRowsPos(STsdbReadHandle* pTsdbReadHandle, int32_t startPos, int32_t endPos,
                                 int32_t numOfExisted, int32_t* start, int32_t* end) {
   *start = -1;
@@ -1891,9 +1874,6 @@ static void copyAllRemainRowsFromFileBlock(STsdbReadHandle* pTsdbReadHandle, STa
   cur->lastKey = tsArray[endPos] + step;
   cur->blockCompleted = true;
 
-  // if the buffer is not full in case of descending order query, move the data in the front of the buffer
-  moveDataToFront(pTsdbReadHandle, numOfRows, numOfCols);
-
   // The value of pos may be -1 or pBlockInfo->rows, and it is invalid in both cases.
   pos = endPos + step;
   updateInfoAfterMerge(pTsdbReadHandle, pCheckInfo, numOfRows, pos);
@@ -1944,18 +1924,18 @@ static void doMergeTwoLevelData(STsdbReadHandle* pTsdbReadHandle, STableCheckInf
   assert(pCols->numOfRows == pBlock->numOfRows && tsArray[0] == pBlock->keyFirst &&
          tsArray[pBlock->numOfRows - 1] == pBlock->keyLast);
 
+  bool ascScan = ASCENDING_TRAVERSE(pTsdbReadHandle->order);
+  int32_t step = ascScan ? 1 : -1;
+
   // for search the endPos, so the order needs to reverse
-  int32_t order = (pTsdbReadHandle->order == TSDB_ORDER_ASC) ? TSDB_ORDER_DESC : TSDB_ORDER_ASC;
+  int32_t order = ascScan ? TSDB_ORDER_DESC : TSDB_ORDER_ASC;
 
-  int32_t step = ASCENDING_TRAVERSE(pTsdbReadHandle->order) ? 1 : -1;
   int32_t numOfCols = (int32_t)(QH_GET_NUM_OF_COLS(pTsdbReadHandle));
-
-  STable* pTable = NULL;
   int32_t endPos = getEndPosInDataBlock(pTsdbReadHandle, &blockInfo);
 
+  STimeWindow* pWin = &blockInfo.window;
   tsdbDebug("%p uid:%" PRIu64 " start merge data block, file block range:%" PRIu64 "-%" PRIu64
-            " rows:%d, start:%d, end:%d, %s",
-            pTsdbReadHandle, pCheckInfo->tableId, blockInfo.window.skey, blockInfo.window.ekey, blockInfo.rows,
+            " rows:%d, start:%d, end:%d, %s", pTsdbReadHandle, pCheckInfo->tableId, pWin->skey, pWin->ekey, blockInfo.rows,
             cur->pos, endPos, pTsdbReadHandle->idStr);
 
   // compared with the data from in-memory buffer, to generate the correct timestamp array list
@@ -1986,20 +1966,16 @@ static void doMergeTwoLevelData(STsdbReadHandle* pTsdbReadHandle, STableCheckInf
       }
 
       TSKEY key = TD_ROW_KEY(row1);
-      if ((key > pTsdbReadHandle->window.ekey && ASCENDING_TRAVERSE(pTsdbReadHandle->order)) ||
-          (key < pTsdbReadHandle->window.ekey && !ASCENDING_TRAVERSE(pTsdbReadHandle->order))) {
+      if ((key > pTsdbReadHandle->window.ekey && ascScan) || (key < pTsdbReadHandle->window.ekey && !ascScan)) {
         break;
       }
 
-      if (((pos > endPos || tsArray[pos] > pTsdbReadHandle->window.ekey) &&
-           ASCENDING_TRAVERSE(pTsdbReadHandle->order)) ||
-          ((pos < endPos || tsArray[pos] < pTsdbReadHandle->window.ekey) &&
-           !ASCENDING_TRAVERSE(pTsdbReadHandle->order))) {
+      if (((pos > endPos || tsArray[pos] > pTsdbReadHandle->window.ekey) && ascScan) ||
+          ((pos < endPos || tsArray[pos] < pTsdbReadHandle->window.ekey) && !ascScan)) {
         break;
       }
 
-      if ((key < tsArray[pos] && ASCENDING_TRAVERSE(pTsdbReadHandle->order)) ||
-          (key > tsArray[pos] && !ASCENDING_TRAVERSE(pTsdbReadHandle->order))) {
+      if ((key < tsArray[pos] && ascScan) || (key > tsArray[pos] && !ascScan)) {
         if (rv1 != TD_ROW_SVER(row1)) {
           //          pSchema1 = tsdbGetTableSchemaByVersion(pTable, memRowVersion(row1));
           rv1 = TD_ROW_SVER(row1);
@@ -2054,11 +2030,8 @@ static void doMergeTwoLevelData(STsdbReadHandle* pTsdbReadHandle, STableCheckInf
         }
 #endif
         if (TD_SUPPORT_UPDATE(pCfg->update)) {
-          if (lastKeyAppend != key) {
-            lastKeyAppend = key;
-            ++curRow;
-          }
           numOfRows = doCopyRowsFromFileBlock(pTsdbReadHandle, pTsdbReadHandle->outputCapacity, curRow, pos, pos);
+          lastKeyAppend = key;
 
           if (rv1 != TD_ROW_SVER(row1)) {
             //            pSchema1 = tsdbGetTableSchemaByVersion(pTable, memRowVersion(row1));
@@ -2068,9 +2041,10 @@ static void doMergeTwoLevelData(STsdbReadHandle* pTsdbReadHandle, STableCheckInf
             //            pSchema2 = tsdbGetTableSchemaByVersion(pTable, memRowVersion(row2));
             rv2 = TD_ROW_SVER(row2);
           }
-          numOfRows +=
-              mergeTwoRowFromMem(pTsdbReadHandle, pTsdbReadHandle->outputCapacity, &curRow, row1, row2, numOfCols,
-                                 pCheckInfo->tableId, pSchema1, pSchema2, pCfg->update, &lastKeyAppend);
+
+          // still assign data into current row
+          mergeTwoRowFromMem(pTsdbReadHandle, pTsdbReadHandle->outputCapacity, &curRow, row1, row2, numOfCols,
+                             pCheckInfo->tableId, pSchema1, pSchema2, pCfg->update, &lastKeyAppend);
 
           if (cur->win.skey == TSKEY_INITIAL_VAL) {
             cur->win.skey = key;
@@ -2081,12 +2055,13 @@ static void doMergeTwoLevelData(STsdbReadHandle* pTsdbReadHandle, STableCheckInf
           cur->mixBlock = true;
 
           moveToNextRowInMem(pCheckInfo);
+          ++curRow;
+
           pos += step;
         } else {
           moveToNextRowInMem(pCheckInfo);
         }
-      } else if ((key > tsArray[pos] && ASCENDING_TRAVERSE(pTsdbReadHandle->order)) ||
-                 (key < tsArray[pos] && !ASCENDING_TRAVERSE(pTsdbReadHandle->order))) {
+      } else if ((key > tsArray[pos] && ascScan) || (key < tsArray[pos] && !ascScan)) {
         if (cur->win.skey == TSKEY_INITIAL_VAL) {
           cur->win.skey = tsArray[pos];
         }
@@ -2112,17 +2087,17 @@ static void doMergeTwoLevelData(STsdbReadHandle* pTsdbReadHandle, STableCheckInf
         int32_t qstart = 0, qend = 0;
         getQualifiedRowsPos(pTsdbReadHandle, pos, end, numOfRows, &qstart, &qend);
 
-        if ((lastKeyAppend != TSKEY_INITIAL_VAL) &&
-            (lastKeyAppend != (ASCENDING_TRAVERSE(pTsdbReadHandle->order) ? tsArray[qstart] : tsArray[qend]))) {
+        if ((lastKeyAppend != TSKEY_INITIAL_VAL) && (lastKeyAppend != (ascScan ? tsArray[qstart] : tsArray[qend]))) {
           ++curRow;
         }
+
         numOfRows = doCopyRowsFromFileBlock(pTsdbReadHandle, pTsdbReadHandle->outputCapacity, curRow, qstart, qend);
         pos += (qend - qstart + 1) * step;
         if (numOfRows > 0) {
           curRow = numOfRows - 1;
         }
 
-        cur->win.ekey = ASCENDING_TRAVERSE(pTsdbReadHandle->order) ? tsArray[qend] : tsArray[qstart];
+        cur->win.ekey = ascScan ? tsArray[qend] : tsArray[qstart];
         cur->lastKey = cur->win.ekey + step;
         lastKeyAppend = cur->win.ekey;
       }
@@ -2134,10 +2109,8 @@ static void doMergeTwoLevelData(STsdbReadHandle* pTsdbReadHandle, STableCheckInf
        * copy them all to result buffer, since it may be overlapped with file data block.
        */
       if (node == NULL ||
-          ((TD_ROW_KEY((STSRow*)SL_GET_NODE_DATA(node)) > pTsdbReadHandle->window.ekey) &&
-           ASCENDING_TRAVERSE(pTsdbReadHandle->order)) ||
-          ((TD_ROW_KEY((STSRow*)SL_GET_NODE_DATA(node)) < pTsdbReadHandle->window.ekey) &&
-           !ASCENDING_TRAVERSE(pTsdbReadHandle->order))) {
+          ((TD_ROW_KEY((STSRow*)SL_GET_NODE_DATA(node)) > pTsdbReadHandle->window.ekey) && ascScan) ||
+          ((TD_ROW_KEY((STSRow*)SL_GET_NODE_DATA(node)) < pTsdbReadHandle->window.ekey) && !ascScan)) {
         // no data in cache or data in cache is greater than the ekey of time window, load data from file block
         if (cur->win.skey == TSKEY_INITIAL_VAL) {
           cur->win.skey = tsArray[pos];
@@ -2149,22 +2122,20 @@ static void doMergeTwoLevelData(STsdbReadHandle* pTsdbReadHandle, STableCheckInf
         numOfRows = doCopyRowsFromFileBlock(pTsdbReadHandle, pTsdbReadHandle->outputCapacity, numOfRows, start, end);
         pos += (end - start + 1) * step;
 
-        cur->win.ekey = ASCENDING_TRAVERSE(pTsdbReadHandle->order) ? tsArray[end] : tsArray[start];
+        cur->win.ekey = ascScan ? tsArray[end] : tsArray[start];
         cur->lastKey = cur->win.ekey + step;
         cur->mixBlock = true;
       }
     }
   }
 
-  cur->blockCompleted =
-      (((pos > endPos || cur->lastKey > pTsdbReadHandle->window.ekey) && ASCENDING_TRAVERSE(pTsdbReadHandle->order)) ||
-       ((pos < endPos || cur->lastKey < pTsdbReadHandle->window.ekey) && !ASCENDING_TRAVERSE(pTsdbReadHandle->order)));
+  cur->blockCompleted = (((pos > endPos || cur->lastKey > pTsdbReadHandle->window.ekey) && ascScan) ||
+       ((pos < endPos || cur->lastKey < pTsdbReadHandle->window.ekey) && !ascScan));
 
-  if (!ASCENDING_TRAVERSE(pTsdbReadHandle->order)) {
+  if (!ascScan) {
     TSWAP(cur->win.skey, cur->win.ekey);
   }
 
-  moveDataToFront(pTsdbReadHandle, numOfRows, numOfCols);
   updateInfoAfterMerge(pTsdbReadHandle, pCheckInfo, numOfRows, pos);
   doCheckGeneratedBlockRange(pTsdbReadHandle);