diff --git a/source/dnode/vnode/src/tsdb/tsdbRead.c b/source/dnode/vnode/src/tsdb/tsdbRead.c
index 67a88d0e9f53dbe5010523f33091d15b285ee5c0..062e91a6a63412392f10037fa2a984b69d4b2028 100644
--- a/source/dnode/vnode/src/tsdb/tsdbRead.c
+++ b/source/dnode/vnode/src/tsdb/tsdbRead.c
@@ -363,12 +363,11 @@ static void resetDataBlockIterator(SDataBlockIter* pIter) {
 }
 
 static bool filesetIteratorNext(SFileSetIter* pIter, int32_t order, STsdbReader* pReader) {
+  pIter->index += 1;
   if (pIter->index >= pIter->numOfFiles) {
     return false;
   }
 
-  pIter->index += 1;
-
   // check file the time range of coverage
   STimeWindow win = {0};
   pReader->status.pCurrentFileSet = (SDFileSet *)taosArrayGet(pIter->pFileList, pIter->index);
@@ -920,7 +919,8 @@ static int32_t doLoadFileBlock(STsdbReader* pReader, SArray* pIndexList, uint32_
     tsdbReadBlock(pReader->pFileReader, pBlockIdx, &mapData, NULL);
 
     STableBlockScanInfo* pScanInfo = taosHashGet(pReader->status.pTableMap, &pBlockIdx->uid, sizeof(int64_t));
-    ASSERT(pScanInfo->pBlockList == NULL || taosArrayGetSize(pScanInfo->pBlockList) == 0);
+    taosArrayClear(pScanInfo->pBlockList);
+
     for (int32_t j = 0; j < mapData.nItem; ++j) {
       SBlock block = {0};
 
@@ -971,18 +971,25 @@ static int32_t doLoadFileBlockData(STsdbReader* pReader, SDataBlockIter* pBlockI
   SBlock* pBlock = taosArrayGet(pBlockScanInfo->pBlockList, pFBlock->tbBlockIdx);
 
  uint8_t *pb = NULL, *pb1 = NULL;
- int32_t code = tsdbReadBlockData(pReader->pFileReader, &pBlockScanInfo->blockIdx, pBlock, pBlockData, /*pReader->suppInfo.colIdList, numOfCols, */&pb, &pb1);
+ int32_t code = tsdbReadBlockData(pReader->pFileReader, &pBlockScanInfo->blockIdx, pBlock, pBlockData, &pb, &pb1);
  if (code != TSDB_CODE_SUCCESS) {
    goto _error;
  }
 
- SColVal cv = {0};
  for(int32_t i = 0; i < taosArrayGetSize(pReader->pResBlock->pDataBlock); ++i) {
-   SColData* pData = (SColData*)taosArrayGet(pBlockData->aColDataP, pReader->suppInfo.slotIds[i]);
    SColumnInfoData* pColData = taosArrayGet(pReader->pResBlock->pDataBlock, i);
-   for(int32_t j = 0; j < pBlockData->nRow; ++j) {
-     tColDataGetValue(pData, j, &cv);
-     colDataAppend(pColData, j, (const char*)&cv.value, cv.isNull);
+   if (pColData->info.colId == PRIMARYKEY_TIMESTAMP_COL_ID) {
+     for (int32_t j = 0; j < pBlockData->nRow; ++j) {
+       colDataAppend(pColData, j, (const char*)&pBlockData->aTSKEY[j], false);
+     }
+   } else {
+     SColVal cv = {0};
+
+     SColData* pData = (SColData*)taosArrayGetP(pBlockData->aColDataP, pReader->suppInfo.slotIds[i]);
+     for (int32_t j = 0; j < pBlockData->nRow; ++j) {
+       tColDataGetValue(pData, j, &cv);
+       colDataAppend(pColData, j, (const char*)&cv.value, cv.isNull);
+     }
    }
  }
 
@@ -2276,7 +2283,7 @@ static bool bufferDataInFileBlockGap(int32_t order, TSDBKEY key, SBlock* pBlock)
 }
 
 static bool keyOverlapFileBlock(TSDBKEY key, SBlock* pBlock, SVersionRange* pVerRange) {
-  return (key.ts >= pBlock->minKey.ts || key.ts <= pBlock->maxKey.ts) /*&& (pBlock->maxVersion >= pVerRange->minVer) && (pBlock->minVersion <= pVerRange->maxVer)*/;
+  return (key.ts >= pBlock->minKey.ts && key.ts <= pBlock->maxKey.ts) /*&& (pBlock->maxVersion >= pVerRange->minVer) && (pBlock->minVersion <= pVerRange->maxVer)*/;
 }
 
 static bool fileBlockShouldLoad(STsdbReader* pReader, SFileDataBlockInfo *pFBlock, SBlock* pBlock, STableBlockScanInfo *pScanInfo, TSDBKEY key) {
@@ -2511,7 +2518,6 @@ static TSDBKEY getCurrentKeyInBuf(SDataBlockIter* pBlockIter, STsdbReader* pRead
 
   SFileDataBlockInfo* pFBlock = getCurrentBlockInfo(pBlockIter);
   STableBlockScanInfo* pScanInfo = taosHashGet(pReader->status.pTableMap, &pFBlock->uid, sizeof(pFBlock->uid));
-  SBlock* pBlock = taosArrayGet(pScanInfo->pBlockList, pFBlock->tbBlockIdx);
 
   initMemIterator(pScanInfo, pReader);
   if (pScanInfo->memHasVal) {
@@ -2563,7 +2569,82 @@ static int32_t moveToNextFile(STsdbReader* pReader, int32_t* numOfBlocks) {
   return TSDB_CODE_SUCCESS;
 }
 
-static int32_t loadDataInFiles(STsdbReader* pReader, bool* exists) {
+static int32_t doBuildDataBlock(STsdbReader* pReader) {
+  int32_t code = TSDB_CODE_SUCCESS;
+
+  SReaderStatus* pStatus = &pReader->status;
+  SDataBlockIter* pBlockIter = &pStatus->blockIter;
+
+  SFileDataBlockInfo* pFBlock = getCurrentBlockInfo(pBlockIter);
+  STableBlockScanInfo* pScanInfo = taosHashGet(pReader->status.pTableMap, &pFBlock->uid, sizeof(pFBlock->uid));
+
+  SBlock* pBlock = taosArrayGet(pScanInfo->pBlockList, pFBlock->tbBlockIdx);
+
+  TSDBKEY key = getCurrentKeyInBuf(pBlockIter, pReader);
+  if (fileBlockShouldLoad(pReader, pFBlock, pBlock, pScanInfo, key)) {
+    SBlockData data = {0};
+    tBlockDataInit(&data);
+
+    code = doLoadFileBlockData(pReader, pBlockIter, pScanInfo, &data);
+    if (code != TSDB_CODE_SUCCESS) {
+      return code;
+    }
+
+    // build composed data block
+    code = buildComposedDataBlock(pReader, pFBlock, pBlock, pScanInfo);
+    if (code != TSDB_CODE_SUCCESS) {
+      return code;
+    }
+  } else if (bufferDataInFileBlockGap(pReader->order, key, pBlock)) {
+    // data in memory that are earlier than current file block
+    TSDBKEY maxKey = {.ts = pReader->window.ekey, .version = pReader->verRange.maxVer};
+    code = buildInmemDataBlock(pReader, pScanInfo, &maxKey);
+    // build data block from in-memory buffer data completed.
+  } else { // whole block is required, return it directly
+    // todo
+    // 1. the version of all rows should be less than the endVersion
+    // 2. current block should not overlap with next neighbor block
+    // 3. current timestamp should not be overlap with each other
+    SDataBlockInfo* pInfo = &pReader->pResBlock->info;
+    pInfo->rows = pBlock->nRow;
+    pInfo->uid  = pScanInfo->uid;
+    pInfo->window.skey = pBlock->minKey.ts;
+    pInfo->window.ekey = pBlock->maxKey.ts;
+    setComposedBlockFlag(pReader, false);
+  }
+
+  return code;
+}
+
+static int32_t buildInmemBlockSeqentially(STsdbReader* pReader) {
+  SReaderStatus* pStatus = &pReader->status;
+
+  while(1) {
+    if (pStatus->pTableIter == NULL) {
+      pStatus->pTableIter = taosHashIterate(pStatus->pTableMap, NULL);
+      if (pStatus->pTableIter == NULL) {
+        return false;
+      }
+    }
+
+    STableBlockScanInfo* pBlockScanInfo = pStatus->pTableIter;
+    initMemIterator(pBlockScanInfo, pReader);
+
+    TSDBKEY maxKey = {.ts = pReader->window.ekey, .version = pReader->verRange.maxVer};
+    buildInmemDataBlock(pReader, pBlockScanInfo, &maxKey);
+    if (pReader->pResBlock->info.rows > 0) {
+      return true;
+    }
+
+    // current table is exhausted, let's try the next table
+    pStatus->pTableIter = taosHashIterate(pStatus->pTableMap, pStatus->pTableIter);
+    if (pStatus->pTableIter == NULL) {
+      return false;
+    }
+  }
+}
+
+static int32_t loadDataInFiles(STsdbReader* pReader) {
   SReaderStatus* pStatus = &pReader->status;
   SFileSetIter*  pFIter = &pStatus->fileIter;
 
@@ -2583,36 +2664,8 @@ static int32_t loadDataInFiles(STsdbReader* pReader, bool* exists) {
         return code;
       }
 
-      SFileDataBlockInfo* pFBlock = getCurrentBlockInfo(pBlockIter);
-      STableBlockScanInfo* pScanInfo = taosHashGet(pReader->status.pTableMap, &pFBlock->uid, sizeof(pFBlock->uid));
-      SBlock* pBlock = taosArrayGet(pScanInfo->pBlockList, pFBlock->tbBlockIdx);
-
-      TSDBKEY key = getCurrentKeyInBuf(pBlockIter, pReader);
-
-      if (fileBlockShouldLoad(pReader, pFBlock, pBlock, pScanInfo, key)) {
-        SBlockData data = {0};
-        doLoadFileBlockData(pReader, pBlockIter, pScanInfo, &data);
+      code = doBuildDataBlock(pReader);
 
-        // build composed data block
-        buildComposedDataBlock(pReader, pFBlock, pBlock, pScanInfo);
-      } else if (bufferDataInFileBlockGap(pReader->order, key, pBlock)) {
-        // data in memory that are earlier than current file block
-        TSDBKEY maxKey = {.ts = pReader->window.ekey, .version = pReader->verRange.maxVer};
-        buildInmemDataBlock(pReader, pScanInfo, &maxKey);
-        // build data block from in-memory buffer data completed.
-      } else { // whole block is required, return it directly
-        // todo
-        // 1. the version of all rows should be less than the endVersion
-        // 2. current block should not overlap with next neighbor block
-        // 3. current timestamp should not be overlap with each other
-        SDataBlockInfo* pInfo = &pReader->pResBlock->info;
-        pInfo->rows = pBlock->nRow;
-        pInfo->uid  = pScanInfo->uid;
-        pInfo->window.skey = pBlock->minKey.ts;
-        pInfo->window.ekey = pBlock->maxKey.ts;
-        setComposedBlockFlag(pReader, false);
-      }
-      *exists = true;
     } else {
       SFileBlockDumpInfo* pDumpInfo = &pReader->status.fBlockDumpInfo;
       SFileDataBlockInfo* pFBlock = getCurrentBlockInfo(&pReader->status.blockIter);
@@ -2629,46 +2682,22 @@ static int32_t loadDataInFiles(STsdbReader* pReader, bool* exists) {
             return code;
           }
 
-          // initialize the block iterator for a new fileset
-          code = initBlockIterator(pReader, pBlockIter, numOfBlocks);
-          if (code != TSDB_CODE_SUCCESS) {
+          // all data files are consumed, try data in buffer
+          if (numOfBlocks == 0) {
+            pReader->status.loadFromFile = false;
             return code;
+          } else {
+            // initialize the block iterator for a new fileset
+            code = initBlockIterator(pReader, pBlockIter, numOfBlocks);
+            if (code != TSDB_CODE_SUCCESS) {
+              return code;
+            }
+
+            doBuildDataBlock(pReader);
           }
-
-          pFBlock = getCurrentBlockInfo(pBlockIter);
-          pScanInfo = taosHashGet(pReader->status.pTableMap, &pFBlock->uid, sizeof(pFBlock->uid));
-          pBlock = taosArrayGet(pScanInfo->pBlockList, pFBlock->tbBlockIdx);
-
-          TSDBKEY key = getCurrentKeyInBuf(pBlockIter, pReader);
-          if (fileBlockShouldLoad(pReader, pFBlock, pBlock, pScanInfo, key)) {
-            SBlockData data = {0};
-            doLoadFileBlockData(pReader, pBlockIter, pScanInfo, &data);
-            // build composed data block
-            buildComposedDataBlock(pReader, pFBlock, pBlock, pScanInfo);
-          } else if (bufferDataInFileBlockGap(pReader->order, key, pBlock)) {
-            // data in memory that are earlier than current file block
-            TSDBKEY maxKey = {.ts = pReader->window.ekey, .version = pReader->verRange.maxVer};
-            buildInmemDataBlock(pReader, pScanInfo, &maxKey);
-            // build data block from in-memory buffer data completed.
-          } else { // whole block is required, return it directly
-            // todo
-            // 1. the version of all rows should be less than the endVersion
-            // 2. current block should not overlap with next neighbor block
-            // 3. current timestamp should not be overlap with each other
-            SDataBlockInfo* pInfo = &pReader->pResBlock->info;
-            pInfo->rows = pBlock->nRow;
-            pInfo->uid  = pScanInfo->uid;
-            pInfo->window.skey = pBlock->minKey.ts;
-            pInfo->window.ekey = pBlock->maxKey.ts;
-            setComposedBlockFlag(pReader, false);
-          }
-          *exists = true;
-
         } else { // try next data block in current file
-          // 1. check if ts in buffer is overlap with current file data block
           blockIteratorNext(pBlockIter);
-
-
+          doBuildDataBlock(pReader);
         }
       } else {
         buildComposedDataBlock(pReader, pFBlock, pBlock, pScanInfo);
@@ -3263,13 +3292,13 @@ void tsdbReaderClose(STsdbReader* pReader) {
 }
 
 bool tsdbNextDataBlock(STsdbReader* pReader) {
-  bool ret = false;
   if (isEmptyQueryTimeWindow(pReader)) {
     return false;
   }
 
   // cleanup the data that belongs to the previous data block
-  blockDataCleanup(pReader->pResBlock);
+  SSDataBlock* pBlock = pReader->pResBlock;
+  blockDataCleanup(pBlock);
 
   int64_t stime = taosGetTimestampUs();
   int64_t elapsedTime = stime;
@@ -3277,41 +3306,20 @@ bool tsdbNextDataBlock(STsdbReader* pReader) {
 
   if (pReader->type == BLOCK_LOAD_OFFSET_ORDER) {
     if (pStatus->loadFromFile) {
-      bool exists = true;
-      int32_t code = loadDataInFiles(pReader, &exists);
+      int32_t code = loadDataInFiles(pReader);
       if (code != TSDB_CODE_SUCCESS) {
         return false;
       }
 
-      if (exists) {
+      if (pBlock->info.rows > 0) {
         return true;
-      } else {  // let's try the in-memory buffer
-
+      } else {
+        buildInmemBlockSeqentially(pReader);
+        return pBlock->info.rows > 0;
       }
     } else { // no data in files, let's try the buffer
-      while(1) {
-        if (pStatus->pTableIter == NULL) {
-          pStatus->pTableIter = taosHashIterate(pStatus->pTableMap, NULL);
-          if (pStatus->pTableIter == NULL) {
-            return false;
-          }
-        }
-
-        STableBlockScanInfo* pBlockScanInfo = pStatus->pTableIter;
-        initMemIterator(pBlockScanInfo, pReader);
-
-        TSDBKEY maxKey = {.ts = pReader->window.ekey, .version = pReader->verRange.maxVer};
-        buildInmemDataBlock(pReader, pBlockScanInfo, &maxKey);
-        if (pReader->pResBlock->info.rows > 0) {
-          return true;
-        }
-
-        // current table is exhausted, let's try the next table
-        pStatus->pTableIter = taosHashIterate(pStatus->pTableMap, pStatus->pTableIter);
-        if (pStatus->pTableIter == NULL) {
-          return false;
-        }
-      }
+      buildInmemBlockSeqentially(pReader);
+      return pBlock->info.rows > 0;
     }
   } else if (pReader->type == BLOCK_LOAD_TABLESEQ_ORDER) {
 
@@ -3351,7 +3359,7 @@ bool tsdbNextDataBlock(STsdbReader* pReader) {
   //   pReader->cost.checkForNextTime += elapsedTime;
   //   return ret;
   // }
-  return ret;
+  return false;
 }
 
 void tsdbRetrieveDataBlockInfo(STsdbReader* pReader, SDataBlockInfo* pDataBlockInfo) {
@@ -3450,40 +3458,6 @@ SArray* tsdbRetrieveDataBlock(STsdbReader* pReader, SArray* pIdList) {
 
     return pReader->pResBlock->pDataBlock;
   }
-  // /**
-  //  * In the following two cases, the data has been loaded to SColumnInfoData.
-  //  * 1. data is from cache, 2. data block is not completed qualified to query time range
-  //  */
-  // if (pReader->cur.fid == INT32_MIN) {
-  //   return pReader->pColumns;
-  // } else {
-  //   SFileBlockInfo* pBlockInfo = &pReader->pDataBlockInfo[pReader->cur.slot];
-  //   STableBlockScanInfo* pCheckInfo = pBlockInfo->pTableCheckInfo;
-
-  //   if (pReader->cur.mixBlock) {
-  //     return pReader->pColumns;
-  //   } else {
-  //     SDataBlockInfo binfo = GET_FILE_DATA_BLOCK_INFO(pCheckInfo, pBlockInfo->compBlock);
-  //     assert(pReader->realNumOfRows <= binfo.rows);
-
-  //     // data block has been loaded, todo extract method
-  //     SDataBlockLoadInfo* pBlockLoadInfo = &pReader->dataBlockLoadInfo;
-
-  //     if (pBlockLoadInfo->slot == pReader->cur.slot && pBlockLoadInfo->fileGroup->fid == pReader->cur.fid &&
-  //         pBlockLoadInfo->uid == pCheckInfo->tableId) {
-  //       return pReader->pColumns;
-  //     } else {  // only load the file block
-  //       SBlock* pBlock = pBlockInfo->compBlock;
-  //       if (doLoadFileBlockData(pReader, pBlock, pCheckInfo, pReader->cur.slot) != TSDB_CODE_SUCCESS) {
-  //         return NULL;
-  //       }
-
-  //       int32_t numOfRows = doCopyRowsFromFileBlock(pReader, pReader->outputCapacity, 0, 0, pBlock->numOfRows - 1);
-  //       return pReader->pColumns;
-  //     }
-  //   }
-  // }
-  return NULL;
 }
 
 void tsdbResetReadHandle(STsdbReader* pReader, SQueryTableDataCond* pCond, int32_t tWinIdx) {