diff --git a/source/dnode/vnode/src/tsdb/tsdbRead.c b/source/dnode/vnode/src/tsdb/tsdbRead.c
index 5191331370b91277a7af1eeeafaec1b3d1d320af..9c711cf8a3ee8b76907a8dc36499043c5c74b9db 100644
--- a/source/dnode/vnode/src/tsdb/tsdbRead.c
+++ b/source/dnode/vnode/src/tsdb/tsdbRead.c
@@ -92,8 +92,8 @@ typedef struct SIOCostSummary {
 typedef struct SBlockLoadSuppInfo {
   SColumnDataAgg*   pstatis;
   SColumnDataAgg**  plist;
-  int16_t*          colIdList;   // default load column
   int32_t*          slotIds;     // colId to slotId
+  char**            buildBuf;    // build string tmp buffer, todo remove it later after all string format being updated.
 } SBlockLoadSuppInfo;
 
 typedef struct SFileSetIter {
@@ -189,16 +189,34 @@ static void setComposedBlockFlag(STsdbReader* pReader, bool composed);
 //   pCompBlockLoadInfo->fileId = -1;
 // }
 
-static int32_t setColumnIdList(STsdbReader* pReader, SSDataBlock* pBlock) {
+static int32_t setColumnIdSlotList(STsdbReader* pReader, SSDataBlock* pBlock) {
+  SBlockLoadSuppInfo* pSupInfo = &pReader->suppInfo;
+
   size_t numOfCols = taosArrayGetSize(pBlock->pDataBlock);
-  pReader->suppInfo.colIdList = taosMemoryCalloc(numOfCols, sizeof(int16_t));
-  if (pReader->suppInfo.colIdList == NULL) {
+  pSupInfo->slotIds = taosMemoryCalloc(numOfCols, sizeof(int16_t));
+  if (pSupInfo->slotIds == NULL) {
+    return TSDB_CODE_OUT_OF_MEMORY;
+  }
+
+  pSupInfo->buildBuf = taosMemoryCalloc(numOfCols, POINTER_BYTES);
+  if (pSupInfo->buildBuf == NULL) {
     return TSDB_CODE_OUT_OF_MEMORY;
   }
 
+  STSchema* pSchema = pReader->pSchema;
   for (int32_t i = 0; i < numOfCols; ++i) {
     SColumnInfoData* pCol = taosArrayGet(pBlock->pDataBlock, i);
-    pReader->suppInfo.colIdList[i] = pCol->info.colId;
+
+    for (int32_t j = 0; j < pSchema->numOfCols; ++j) {
+      if (pCol->info.colId == pSchema->columns[j].colId) {
+        pSupInfo->slotIds[i] = j;
+        break;
+      }
+    }
+
+    if (IS_VAR_DATA_TYPE(pCol->info.type)) {
+      pSupInfo->buildBuf[i] = taosMemoryMalloc(pCol->info.bytes);
+    }
   }
 
   return TSDB_CODE_SUCCESS;
@@ -426,8 +444,7 @@ static int32_t tsdbReaderCreate(SVnode* pVnode, SQueryTableDataCond* pCond, STsd
 
     blockDataEnsureCapacity(pReader->pResBlock, pReader->capacity);
 
-    setColumnIdList(pReader, pReader->pResBlock);
-    pReader->suppInfo.slotIds = taosMemoryCalloc(pCond->numOfCols, sizeof(int32_t));
+    setColumnIdSlotList(pReader, pReader->pResBlock);
     pReader->suppInfo.plist = taosMemoryCalloc(pCond->numOfCols, POINTER_BYTES);
   }
 
@@ -2504,7 +2521,6 @@ static int32_t loadDataInFiles(STsdbReader* pReader, bool* exists) {
         return code;
       }
 
-      // todo extract method: getCurrentKeyInBuf()
       SFileDataBlockInfo* pFBlock = getCurrentBlockInfo(pBlockIter);
       STableBlockScanInfo* pScanInfo = taosHashGet(pReader->status.pTableMap, &pFBlock->uid, sizeof(pFBlock->uid));
       SBlock* pBlock = taosArrayGet(pScanInfo->pBlockList, pFBlock->tbBlockIdx);
@@ -2522,7 +2538,10 @@ static int32_t loadDataInFiles(STsdbReader* pReader, bool* exists) {
         buildInmemDataBlock(pReader, pScanInfo, &maxKey);
         // build data block from in-memory buffer data completed.
       } else { // whole block is required, return it directly
-        // todo check the data version
+        // 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;
@@ -2740,12 +2759,30 @@ int32_t doAppendOneRow(SSDataBlock* pBlock, STsdbReader* pReader, STSRow* pTSRow
   int32_t numOfRows = pBlock->info.rows;
   int32_t numOfCols = (int32_t)taosArrayGetSize(pBlock->pDataBlock);
 
+  SBlockLoadSuppInfo* pSupInfo = &pReader->suppInfo;
+
   SColVal colVal = {0};
   for(int32_t i = 0; i < numOfCols; ++i) {
     SColumnInfoData* pColInfoData = taosArrayGet(pBlock->pDataBlock, i);
+    int32_t slotId = pSupInfo->slotIds[i];
 
-    tTSRowGetVal(pTSRow, pReader->pSchema, pColInfoData->info.colId, &colVal);
-    colDataAppend(pColInfoData, numOfRows, (const char*)&colVal.value, colVal.isNull);
+    if (pColInfoData->info.colId == PRIMARYKEY_TIMESTAMP_COL_ID && slotId == 0) {
+      colDataAppend(pColInfoData, numOfRows, (const char*) &pTSRow->ts, false);
+    } else {
+      tTSRowGetVal(pTSRow, pReader->pSchema, slotId, &colVal);
+
+      if (IS_VAR_DATA_TYPE(colVal.type)) {
+        if (colVal.isNull) {
+          colDataAppendNULL(pColInfoData, numOfRows);
+        } else {
+          varDataSetLen(pSupInfo->buildBuf[i], colVal.value.nData);
+          memcpy(varDataVal(pSupInfo->buildBuf[i]), colVal.value.pData, colVal.value.nData);
+          colDataAppend(pColInfoData, numOfRows, pSupInfo->buildBuf[i], false);
+        }
+      } else {
+        colDataAppend(pColInfoData, numOfRows, (const char*)&colVal.value, colVal.isNull);
+      }
+    }
   }
 
   pBlock->info.rows += 1;
@@ -3135,7 +3172,7 @@ bool tsdbNextDataBlock(STsdbReader* pReader) {
         }
 
         // current table is exhausted, let's try the next table
-        pStatus->pTableIter = taosHashIterate(pStatus->pTableMap, &pStatus->pTableIter);
+        pStatus->pTableIter = taosHashIterate(pStatus->pTableMap, pStatus->pTableIter);
         if (pStatus->pTableIter == NULL) {
           return false;
         }