diff --git a/source/dnode/vnode/src/tsdb/tsdbSnapshot.c b/source/dnode/vnode/src/tsdb/tsdbSnapshot.c
index d9a67ce4871d3267eb4759251f8ab7043cfc1bb6..932cf9f9ae9888c72e347f47b15d23d0eca9e788 100644
--- a/source/dnode/vnode/src/tsdb/tsdbSnapshot.c
+++ b/source/dnode/vnode/src/tsdb/tsdbSnapshot.c
@@ -488,52 +488,42 @@ _err:
   return code;
 }
 
-static int32_t tsdbSnapWriteTableDataAhead(STsdbSnapWriter* pWriter, TABLEID id) {
+static int32_t tsdbSnapMoveWriteTableData(STsdbSnapWriter* pWriter, SBlockIdx* pBlockIdx) {
   int32_t code = 0;
 
-  if (pWriter->pDataFReader == NULL) goto _exit;
-
-  while (true) {
-    if (pWriter->iBlockIdx >= taosArrayGetSize(pWriter->aBlockIdx)) break;
-
-    SBlockIdx* pBlockIdx = (SBlockIdx*)taosArrayGet(pWriter->aBlockIdx, pWriter->iBlockIdx);
-    int32_t    c = tTABLEIDCmprFn(pBlockIdx, &id);
-
-    if (c >= 0) break;
-
-    pWriter->iBlockIdx++;
-
-    code = tsdbReadBlock(pWriter->pDataFReader, pBlockIdx, &pWriter->mBlock, NULL);
-    if (code) goto _err;
-
-    SBlock block;
-    tMapDataReset(&pWriter->mBlockW);
-    for (int32_t iBlock = 0; iBlock < pWriter->mBlock.nItem; iBlock++) {
-      tMapDataGetItemByIdx(&pWriter->mBlock, iBlock, &block, tGetBlock);
+  code = tsdbReadBlock(pWriter->pDataFReader, pBlockIdx, &pWriter->mBlock, NULL);
+  if (code) goto _err;
 
-      if (block.last) {
-        code = tsdbReadBlockData(pWriter->pDataFReader, pBlockIdx, &block, &pWriter->bDataR, NULL, NULL);
-        if (code) goto _err;
+  // SBlockData
+  SBlock block;
+  tMapDataReset(&pWriter->mBlockW);
+  for (int32_t iBlock = 0; iBlock < pWriter->mBlock.nItem; iBlock++) {
+    tMapDataGetItemByIdx(&pWriter->mBlock, iBlock, &block, tGetBlock);
 
-        tBlockReset(&block);
-        block.last = 1;
-        code = tsdbWriteBlockData(pWriter->pDataFWriter, &pWriter->bDataR, NULL, NULL, pBlockIdx, &block,
-                                  pWriter->cmprAlg);
-        if (code) goto _err;
-      }
+    if (block.last) {
+      code = tsdbReadBlockData(pWriter->pDataFReader, pBlockIdx, &block, &pWriter->bDataR, NULL, NULL);
+      if (code) goto _err;
 
-      code = tMapDataPutItem(&pWriter->mBlockW, &block, tPutBlock);
+      tBlockReset(&block);
+      block.last = 1;
+      code =
+          tsdbWriteBlockData(pWriter->pDataFWriter, &pWriter->bDataR, NULL, NULL, pBlockIdx, &block, pWriter->cmprAlg);
       if (code) goto _err;
     }
 
-    SBlockIdx blockIdx = {.suid = pBlockIdx->suid, .uid = pBlockIdx->uid};
-    code = tsdbWriteBlock(pWriter->pDataFWriter, &pWriter->mBlockW, NULL, &blockIdx);
+    code = tMapDataPutItem(&pWriter->mBlockW, &block, tPutBlock);
     if (code) goto _err;
+  }
 
-    if (taosArrayPush(pWriter->aBlockIdxW, &blockIdx) == NULL) {
-      code = TSDB_CODE_OUT_OF_MEMORY;
-      goto _err;
-    }
+  // SBlock
+  SBlockIdx blockIdx = {.suid = pBlockIdx->suid, .uid = pBlockIdx->uid};
+  code = tsdbWriteBlock(pWriter->pDataFWriter, &pWriter->mBlockW, NULL, &blockIdx);
+  if (code) goto _err;
+
+  // SBlockIdx
+  if (taosArrayPush(pWriter->aBlockIdxW, &blockIdx) == NULL) {
+    code = TSDB_CODE_OUT_OF_MEMORY;
+    goto _err;
   }
 
 _exit:
@@ -543,77 +533,19 @@ _err:
   return code;
 }
 
-static int32_t tsdbSnapWriteDataImpl(STsdbSnapWriter* pWriter, TABLEID id) {
+static int32_t tsdbSnapWriteTableDataImpl(STsdbSnapWriter* pWriter) {
   int32_t     code = 0;
   SBlockData* pBlockData = &pWriter->bData;
-  TSDBKEY     keyFirst = tBlockDataFirstKey(pBlockData);
-  TSDBKEY     keyLast = tBlockDataLastKey(pBlockData);
-
-  // TABLE ====================================
-
-  // end last table write if should
-  if (pWriter->pBlockIdxW) {
-    int32_t c = tTABLEIDCmprFn(pWriter->pBlockIdxW, &id);
-    if (c < 0) {
-      // end
-      code = tsdbSnapWriteTableDataEnd(pWriter);
-      if (code) goto _err;
+  int32_t     iRow = 0;
+  TSDBROW     row;
+  TSDBROW*    pRow = &row;
 
-      // reset
-      pWriter->pBlockIdxW = NULL;
-    } else if (c > 0) {
-      ASSERT(0);
-    }
-  }
-
-  // start new table data write if need
-  if (pWriter->pBlockIdxW == NULL) {
-    // write table data ahead
-    code = tsdbSnapWriteTableDataAhead(pWriter, id);
-    if (code) goto _err;
-
-    // reader
-    if (pWriter->iBlockIdx < taosArrayGetSize(pWriter->aBlockIdx)) {
-      ASSERT(pWriter->pDataFReader);
-
-      pWriter->pBlockIdx = (SBlockIdx*)taosArrayGet(pWriter->aBlockIdx, pWriter->iBlock);
-      int32_t c = tTABLEIDCmprFn(pWriter->pBlockIdx, &id);
-      if (c) {
-        ASSERT(c > 0);
-        pWriter->pBlockIdx = NULL;
-      } else {
-        pWriter->iBlockIdx++;
-      }
-    } else {
-      pWriter->pBlockIdx = NULL;
-    }
-
-    if (pWriter->pBlockIdx) {
-      code = tsdbReadBlock(pWriter->pDataFReader, pWriter->pBlockIdx, &pWriter->mBlock, NULL);
-      if (code) goto _err;
-    } else {
-      tMapDataReset(&pWriter->mBlock);
-    }
-    pWriter->iBlock = 0;
-    pWriter->pBlockData = NULL;
-    pWriter->iRow = 0;
-
-    // writer
-    pWriter->pBlockIdxW = &pWriter->blockIdxW;
-    pWriter->pBlockIdxW->suid = id.suid;
-    pWriter->pBlockIdxW->uid = id.uid;
-
-    tBlockReset(&pWriter->blockW);
-    tBlockDataReset(&pWriter->bDataW);
-    tMapDataReset(&pWriter->mBlockW);
-  }
-
-  ASSERT(pWriter->pBlockIdxW && pWriter->pBlockIdxW->suid == id.suid && pWriter->pBlockIdxW->uid == id.uid);
-  ASSERT(pWriter->pBlockIdx == NULL || (pWriter->pBlockIdx->suid == id.suid && pWriter->pBlockIdx->uid == id.uid));
+  // correct schema
+  code = tBlockDataCorrectSchema(&pWriter->bDataW, pBlockData);
+  if (code) goto _err;
 
-  // BLOCK ====================================
-  int32_t  iRow = 0;
-  TSDBROW* pRow = &tsdbRowFromBlockData(pBlockData, iRow);
+  // loop to merge
+  *pRow = tsdbRowFromBlockData(pBlockData, iRow);
   while (true) {
     if (pRow == NULL) break;
 
@@ -630,7 +562,7 @@ static int32_t tsdbSnapWriteDataImpl(STsdbSnapWriter* pWriter, TABLEID id) {
 
         iRow++;
         if (iRow < pWriter->pBlockData->nRow) {
-          pRow = &tsdbRowFromBlockData(pBlockData, iRow);
+          *pRow = tsdbRowFromBlockData(pBlockData, iRow);
         } else {
           pRow = NULL;
         }
@@ -644,55 +576,60 @@ static int32_t tsdbSnapWriteDataImpl(STsdbSnapWriter* pWriter, TABLEID id) {
         }
       }
     } else {
-      SBlock block;
+      TSDBKEY key = TSDBROW_KEY(pRow);
 
-      if (pWriter->iBlock < pWriter->mBlock.nItem) {
-        tMapDataGetItemByIdx(&pWriter->mBlock, pWriter->iBlock, &block, tGetBlock);
+      while (true) {
+        if (pWriter->iBlock >= pWriter->mBlock.nItem) break;
+
+        SBlock  block;
         int32_t c;
 
-        c = tsdbKeyCmprFn(&block.maxKey, &TSDBROW_KEY(pRow));
+        tMapDataGetItemByIdx(&pWriter->mBlock, pWriter->iBlock, &block, tGetBlock);
 
-        ASSERT(c);
+        if (block.last) {
+          pWriter->pBlockData = &pWriter->bDataR;
 
-        if (c < 0) {
-          code = tMapDataPutItem(&pWriter->mBlockW, &block, tPutBlock);
+          code = tsdbReadBlockData(pWriter->pDataFReader, pWriter->pBlockIdx, &block, pWriter->pBlockData, NULL, NULL);
           if (code) goto _err;
+          pWriter->iRow = 0;
 
           pWriter->iBlock++;
-          continue;
+          break;
         }
 
-        c = tsdbKeyCmprFn(&block.minKey, &TSDBROW_KEY(pRow));
+        c = tsdbKeyCmprFn(&block.maxKey, &key);
 
         ASSERT(c);
 
-        if (c > 0) {
-          code = tBlockDataAppendRow(&pWriter->bDataW, pRow, NULL);
+        if (c > 0) break;
+
+        if (pWriter->bDataW.nRow) {
+          pWriter->blockW.last = 0;
+          code = tsdbWriteBlockData(pWriter->pDataFWriter, &pWriter->bDataW, NULL, NULL, pWriter->pBlockIdxW,
+                                    &pWriter->blockW, pWriter->cmprAlg);
           if (code) goto _err;
 
-          iRow++;
-          if (iRow < pWriter->pBlockData->nRow) {
-            pRow = &tsdbRowFromBlockData(pBlockData, iRow);
-          } else {
-            pRow = NULL;
-          }
+          code = tMapDataPutItem(&pWriter->mBlockW, &pWriter->blockW, tPutBlock);
+          if (code) goto _err;
 
-          goto _check_write;
+          tBlockReset(&pWriter->blockW);
+          tBlockDataClearData(&pWriter->bDataW);
         }
 
-        pWriter->pBlockData = &pWriter->bDataR;
-        code = tsdbReadBlockData(pWriter->pDataFReader, pWriter->pBlockIdx, &block, pWriter->pBlockData, NULL, NULL);
+        code = tMapDataPutItem(&pWriter->mBlockW, &block, tPutBlock);
         if (code) goto _err;
 
-        pWriter->iRow = 0;
+        pWriter->iBlock++;
       }
 
+      if (pWriter->pBlockData) continue;
+
       code = tBlockDataAppendRow(&pWriter->bDataW, pRow, NULL);
       if (code) goto _err;
 
       iRow++;
-      if (iRow < pWriter->pBlockData->nRow) {
-        pRow = &tsdbRowFromBlockData(pBlockData, iRow);
+      if (iRow < pBlockData->nRow) {
+        *pRow = tsdbRowFromBlockData(pBlockData, iRow);
       } else {
         pRow = NULL;
       }
@@ -713,6 +650,91 @@ static int32_t tsdbSnapWriteDataImpl(STsdbSnapWriter* pWriter, TABLEID id) {
     tBlockDataClearData(&pWriter->bDataW);
   }
 
+  return code;
+
+_err:
+  return code;
+}
+
+static int32_t tsdbSnapWriteTableData(STsdbSnapWriter* pWriter, TABLEID id) {
+  int32_t     code = 0;
+  SBlockData* pBlockData = &pWriter->bData;
+  TSDBKEY     keyFirst = tBlockDataFirstKey(pBlockData);
+  TSDBKEY     keyLast = tBlockDataLastKey(pBlockData);
+
+  // end last table write if should
+  if (pWriter->pBlockIdxW) {
+    int32_t c = tTABLEIDCmprFn(pWriter->pBlockIdxW, &id);
+    if (c < 0) {
+      // end
+      code = tsdbSnapWriteTableDataEnd(pWriter);
+      if (code) goto _err;
+
+      // reset
+      pWriter->pBlockIdxW = NULL;
+    } else if (c > 0) {
+      ASSERT(0);
+    }
+  }
+
+  // start new table data write if need
+  if (pWriter->pBlockIdxW == NULL) {
+    // write table data ahead
+    while (true) {
+      if (pWriter->iBlockIdx >= taosArrayGetSize(pWriter->aBlockIdx)) break;
+
+      SBlockIdx* pBlockIdx = (SBlockIdx*)taosArrayGet(pWriter->aBlockIdx, pWriter->iBlockIdx);
+      int32_t    c = tTABLEIDCmprFn(pBlockIdx, &id);
+
+      if (c >= 0) break;
+
+      code = tsdbSnapMoveWriteTableData(pWriter, pBlockIdx);
+      if (code) goto _err;
+
+      pWriter->iBlockIdx++;
+    }
+
+    // reader
+    if (pWriter->iBlockIdx < taosArrayGetSize(pWriter->aBlockIdx)) {
+      ASSERT(pWriter->pDataFReader);
+
+      SBlockIdx* pBlockIdx = (SBlockIdx*)taosArrayGet(pWriter->aBlockIdx, pWriter->iBlock);
+      int32_t    c = tTABLEIDCmprFn(pBlockIdx, &id);
+
+      ASSERT(c >= 0);
+
+      if (c == 0) {
+        pWriter->pBlockIdx = pBlockIdx;
+        pWriter->iBlockIdx++;
+      }
+    }
+
+    if (pWriter->pBlockIdx) {
+      code = tsdbReadBlock(pWriter->pDataFReader, pWriter->pBlockIdx, &pWriter->mBlock, NULL);
+      if (code) goto _err;
+    } else {
+      tMapDataReset(&pWriter->mBlock);
+    }
+    pWriter->iBlock = 0;
+    pWriter->pBlockData = NULL;
+    pWriter->iRow = 0;
+
+    // writer
+    pWriter->pBlockIdxW = &pWriter->blockIdxW;
+    pWriter->pBlockIdxW->suid = id.suid;
+    pWriter->pBlockIdxW->uid = id.uid;
+
+    tBlockReset(&pWriter->blockW);
+    tBlockDataReset(&pWriter->bDataW);
+    tMapDataReset(&pWriter->mBlockW);
+  }
+
+  ASSERT(pWriter->pBlockIdxW && pWriter->pBlockIdxW->suid == id.suid && pWriter->pBlockIdxW->uid == id.uid);
+  ASSERT(pWriter->pBlockIdx == NULL || (pWriter->pBlockIdx->suid == id.suid && pWriter->pBlockIdx->uid == id.uid));
+
+  code = tsdbSnapWriteTableDataImpl(pWriter);
+  if (code) goto _err;
+
 _exit:
   return code;
 
@@ -723,11 +745,10 @@ _err:
 }
 
 static int32_t tsdbSnapWriteData(STsdbSnapWriter* pWriter, uint8_t* pData, uint32_t nData) {
-  int32_t       code = 0;
-  STsdb*        pTsdb = pWriter->pTsdb;
-  SSnapDataHdr* pHdr = (SSnapDataHdr*)pData;
-  TABLEID       id = *(TABLEID*)(&pHdr[1]);
-  int64_t       n;
+  int32_t code = 0;
+  STsdb*  pTsdb = pWriter->pTsdb;
+  TABLEID id = *(TABLEID*)(pData + sizeof(SSnapDataHdr));
+  int64_t n;
 
   // decode
   SBlockData* pBlockData = &pWriter->bData;
@@ -742,13 +763,13 @@ static int32_t tsdbSnapWriteData(STsdbSnapWriter* pWriter, uint8_t* pData, uint3
   ASSERT(fid == tsdbKeyFid(keyLast.ts, pWriter->minutes, pWriter->precision));
   if (pWriter->pDataFWriter == NULL || pWriter->fid != fid) {
     // end last file data write if need
-    code = tsdbSnapWriteDataEnd(pWriter);  // todo
+    code = tsdbSnapWriteDataEnd(pWriter);
     if (code) goto _err;
 
     pWriter->fid = fid;
 
     // read
-    SDFileSet* pSet = tsdbFSStateGetDFileSet(pTsdb->fs->nState, fid, TD_EQ);  // todo: check nState is valid
+    SDFileSet* pSet = tsdbFSStateGetDFileSet(pTsdb->fs->nState, fid, TD_EQ);
     if (pSet) {
       code = tsdbDataFReaderOpen(&pWriter->pDataFReader, pTsdb, pSet);
       if (code) goto _err;
@@ -763,8 +784,9 @@ static int32_t tsdbSnapWriteData(STsdbSnapWriter* pWriter, uint8_t* pData, uint3
     pWriter->pBlockIdx = NULL;
     tMapDataReset(&pWriter->mBlock);
     pWriter->iBlock = 0;
-    tBlockDataReset(&pWriter->bDataR);
+    pWriter->pBlockData = NULL;
     pWriter->iRow = 0;
+    tBlockDataReset(&pWriter->bDataR);
 
     // write
     SDFileSet wSet;
@@ -789,12 +811,12 @@ static int32_t tsdbSnapWriteData(STsdbSnapWriter* pWriter, uint8_t* pData, uint3
     if (code) goto _err;
 
     taosArrayClear(pWriter->aBlockIdxW);
-    pWriter->pBlockIdxW = NULL;
     tMapDataReset(&pWriter->mBlockW);
+    pWriter->pBlockIdxW = NULL;
     tBlockDataReset(&pWriter->bDataW);
   }
 
-  code = tsdbSnapWriteDataImpl(pWriter, id);
+  code = tsdbSnapWriteTableData(pWriter, id);
   if (code) goto _err;
 
   tsdbInfo("vgId:%d vnode snapshot tsdb write data, fid:%d suid:%" PRId64 " uid:%" PRId64 " nRow:%d",