diff --git a/source/dnode/vnode/src/inc/tsdb.h b/source/dnode/vnode/src/inc/tsdb.h
index 5a2e462c8cd69598ee8642c7109983c97c034294..2efb00ae32c510211a0ac0d6c44450fa1b48464f 100644
--- a/source/dnode/vnode/src/inc/tsdb.h
+++ b/source/dnode/vnode/src/inc/tsdb.h
@@ -202,6 +202,7 @@ int32_t tsdbCmprColData(SColData *pColData, int8_t cmprAlg, SBlockCol *pBlockCol
                         uint8_t **ppBuf);
 int32_t tsdbDecmprColData(uint8_t *pIn, SBlockCol *pBlockCol, int8_t cmprAlg, int32_t nVal, SColData *pColData,
                           uint8_t **ppBuf);
+int32_t tRowInfoCmprFn(const void *p1, const void *p2);
 // tsdbMemTable ==============================================================================================
 // SMemTable
 int32_t  tsdbMemTableCreate(STsdb *pTsdb, SMemTable **ppMemTable);
diff --git a/source/dnode/vnode/src/inc/vnodeInt.h b/source/dnode/vnode/src/inc/vnodeInt.h
index 75367883f1d82edf349bbccbee5552dcf299a003..2501af7f04203f895513cc22aacbe63d0fb64b8d 100644
--- a/source/dnode/vnode/src/inc/vnodeInt.h
+++ b/source/dnode/vnode/src/inc/vnodeInt.h
@@ -247,7 +247,7 @@ int32_t tsdbSnapReaderClose(STsdbSnapReader** ppReader);
 int32_t tsdbSnapRead(STsdbSnapReader* pReader, uint8_t** ppData);
 // STsdbSnapWriter ========================================
 int32_t tsdbSnapWriterOpen(STsdb* pTsdb, int64_t sver, int64_t ever, STsdbSnapWriter** ppWriter);
-int32_t tsdbSnapWrite(STsdbSnapWriter* pWriter, uint8_t* pData, uint32_t nData);
+int32_t tsdbSnapWrite(STsdbSnapWriter* pWriter, SSnapDataHdr* pHdr);
 int32_t tsdbSnapWriterPrepareClose(STsdbSnapWriter* pWriter);
 int32_t tsdbSnapWriterClose(STsdbSnapWriter** ppWriter, int8_t rollback);
 // STqSnapshotReader ==
diff --git a/source/dnode/vnode/src/sma/smaSnapshot.c b/source/dnode/vnode/src/sma/smaSnapshot.c
index 34f884f9f95776be10f1416fdf50f99a8fafce6e..0a6fac0fe7c2d6c724855907e61f498a82abbd57 100644
--- a/source/dnode/vnode/src/sma/smaSnapshot.c
+++ b/source/dnode/vnode/src/sma/smaSnapshot.c
@@ -423,10 +423,10 @@ int32_t rsmaSnapWrite(SRSmaSnapWriter* pWriter, uint8_t* pData, uint32_t nData)
   // rsma1/rsma2
   if (pHdr->type == SNAP_DATA_RSMA1) {
     pHdr->type = SNAP_DATA_TSDB;
-    code = tsdbSnapWrite(pWriter->pDataWriter[0], pData, nData);
+    code = tsdbSnapWrite(pWriter->pDataWriter[0], pHdr);
   } else if (pHdr->type == SNAP_DATA_RSMA2) {
     pHdr->type = SNAP_DATA_TSDB;
-    code = tsdbSnapWrite(pWriter->pDataWriter[1], pData, nData);
+    code = tsdbSnapWrite(pWriter->pDataWriter[1], pHdr);
   } else if (pHdr->type == SNAP_DATA_QTASK) {
     code = rsmaSnapWriteQTaskInfo(pWriter, pData, nData);
   } else {
diff --git a/source/dnode/vnode/src/tsdb/tsdbSnapshot.c b/source/dnode/vnode/src/tsdb/tsdbSnapshot.c
index 08d52554c6cf7452f201e745afe2a99c632dd77f..b2574ddaddf8be360b9b23a4421b6c1c5b2795db 100644
--- a/source/dnode/vnode/src/tsdb/tsdbSnapshot.c
+++ b/source/dnode/vnode/src/tsdb/tsdbSnapshot.c
@@ -15,6 +15,280 @@
 
 #include "tsdb.h"
 
+extern int32_t tsdbReadDataBlockEx(SDataFReader* pReader, SDataBlk* pDataBlk, SBlockData* pBlockData);
+
+// STsdbDataIter2 ========================================
+#define TSDB_MEM_TABLE_DATA_ITER 0
+#define TSDB_DATA_FILE_DATA_ITER 1
+#define TSDB_STT_FILE_DATA_ITER  2
+
+typedef struct STsdbDataIter2 STsdbDataIter2;
+struct STsdbDataIter2 {
+  STsdbDataIter2* next;
+  SRBTreeNode     rbtn;
+
+  int32_t  type;
+  SRowInfo rowInfo;
+  union {
+    // TSDB_MEM_TABLE_DATA_ITER
+    struct {
+      SMemTable* pMemTable;
+    } mIter;
+
+    // TSDB_DATA_FILE_DATA_ITER
+    struct {
+      SDataFReader* pReader;
+      SArray*       aBlockIdx;  // SArray<SBlockIdx>
+      SMapData      mDataBlk;
+      SBlockData    bData;
+      int32_t       iBlockIdx;
+      int32_t       iDataBlk;
+      int32_t       iRow;
+
+    } dIter;
+
+    // TSDB_STT_FILE_DATA_ITER
+    struct {
+      SDataFReader* pReader;
+      int32_t       iStt;
+      SArray*       aSttBlk;
+      SBlockData    bData;
+      int32_t       iSttBlk;
+      int32_t       iRow;
+    } sIter;
+  };
+};
+
+#define TSDB_RBTN_TO_DATA_ITER(pNode) ((STsdbDataIter2*)(((char*)pNode) - offsetof(STsdbDataIter2, rbtn)))
+
+/* open */
+static int32_t tsdbOpenDataFileDataIter(SDataFReader* pReader, STsdbDataIter2** ppIter) {
+  int32_t code = 0;
+  int32_t lino = 0;
+
+  // create handle
+  STsdbDataIter2* pIter = (STsdbDataIter2*)taosMemoryCalloc(1, sizeof(*pIter));
+  if (pIter == NULL) {
+    code = TSDB_CODE_OUT_OF_MEMORY;
+    TSDB_CHECK_CODE(code, lino, _exit);
+  }
+
+  pIter->type = TSDB_DATA_FILE_DATA_ITER;
+  pIter->dIter.pReader = pReader;
+  if ((pIter->dIter.aBlockIdx = taosArrayInit(0, sizeof(SBlockIdx))) == NULL) {
+    code = TSDB_CODE_OUT_OF_MEMORY;
+    TSDB_CHECK_CODE(code, lino, _exit);
+  }
+
+  code = tBlockDataCreate(&pIter->dIter.bData);
+  TSDB_CHECK_CODE(code, lino, _exit);
+
+  pIter->dIter.iBlockIdx = -1;
+  pIter->dIter.iDataBlk = -1;
+  pIter->dIter.iRow = -1;
+
+  // read data
+  code = tsdbReadBlockIdx(pReader, pIter->dIter.aBlockIdx);
+  TSDB_CHECK_CODE(code, lino, _exit);
+
+  if (taosArrayGetSize(pIter->dIter.aBlockIdx) == 0) goto _clear;
+
+_exit:
+  if (code) {
+    if (pIter) {
+    _clear:
+      tBlockDataDestroy(&pIter->dIter.bData, 1);
+      taosArrayDestroy(pIter->dIter.aBlockIdx);
+      taosMemoryFree(pIter);
+      pIter = NULL;
+    }
+  }
+  *ppIter = pIter;
+  return code;
+}
+
+static int32_t tsdbOpenSttFileDataIter(SDataFReader* pReader, int32_t iStt, STsdbDataIter2** ppIter) {
+  int32_t code = 0;
+  int32_t lino = 0;
+
+  // create handle
+  STsdbDataIter2* pIter = (STsdbDataIter2*)taosMemoryCalloc(1, sizeof(*pIter));
+  if (pIter == NULL) {
+    code = TSDB_CODE_OUT_OF_MEMORY;
+    TSDB_CHECK_CODE(code, lino, _exit);
+  }
+
+  pIter->type = TSDB_STT_FILE_DATA_ITER;
+  pIter->sIter.pReader = pReader;
+  pIter->sIter.iStt = iStt;
+  pIter->sIter.aSttBlk = taosArrayInit(0, sizeof(SSttBlk));
+  if (pIter->sIter.aSttBlk == NULL) {
+    code = TSDB_CODE_OUT_OF_MEMORY;
+    TSDB_CHECK_CODE(code, lino, _exit);
+  }
+
+  code = tBlockDataCreate(&pIter->sIter.bData);
+  TSDB_CHECK_CODE(code, lino, _exit);
+
+  pIter->sIter.iSttBlk = -1;
+  pIter->sIter.iRow = -1;
+
+  // read data
+  code = tsdbReadSttBlk(pReader, iStt, pIter->sIter.aSttBlk);
+  TSDB_CHECK_CODE(code, lino, _exit);
+
+  if (taosArrayGetSize(pIter->sIter.aSttBlk) == 0) goto _clear;
+
+_exit:
+  if (code) {
+    if (pIter) {
+    _clear:
+      taosArrayDestroy(pIter->sIter.aSttBlk);
+      tBlockDataDestroy(&pIter->sIter.bData, 1);
+      taosMemoryFree(pIter);
+      pIter = NULL;
+    }
+  }
+  *ppIter = pIter;
+  return code;
+}
+
+/* close */
+static void tsdbCloseDataFileDataIter(STsdbDataIter2* pIter) {
+  tBlockDataDestroy(&pIter->dIter.bData, 1);
+  tMapDataClear(&pIter->dIter.mDataBlk);
+  taosArrayDestroy(pIter->dIter.aBlockIdx);
+  taosMemoryFree(pIter);
+}
+
+static void tsdbCloseSttFileDataIter(STsdbDataIter2* pIter) {
+  tBlockDataDestroy(&pIter->sIter.bData, 1);
+  taosArrayDestroy(pIter->sIter.aSttBlk);
+  taosMemoryFree(pIter);
+}
+
+static void tsdbCloseDataIter2(STsdbDataIter2* pIter) {
+  if (pIter->type == TSDB_MEM_TABLE_DATA_ITER) {
+    ASSERT(0);
+  } else if (pIter->type == TSDB_DATA_FILE_DATA_ITER) {
+    tsdbCloseDataFileDataIter(pIter);
+  } else if (pIter->type == TSDB_STT_FILE_DATA_ITER) {
+    tsdbCloseSttFileDataIter(pIter);
+  } else {
+    ASSERT(0);
+  }
+}
+
+/* cmpr */
+static int32_t tsdbDataIterCmprFn(const SRBTreeNode* pNode1, const SRBTreeNode* pNode2) {
+  STsdbDataIter2* pIter1 = TSDB_RBTN_TO_DATA_ITER(pNode1);
+  STsdbDataIter2* pIter2 = TSDB_RBTN_TO_DATA_ITER(pNode2);
+  return tRowInfoCmprFn(&pIter1->rowInfo, &pIter2->rowInfo);
+}
+
+/* seek */
+
+/* iter next */
+static int32_t tsdbDataFileDataIterNext(STsdbDataIter2* pIter) {
+  int32_t code = 0;
+  int32_t lino = 0;
+
+  for (;;) {
+    if (++pIter->dIter.iRow < pIter->dIter.bData.nRow) {
+      pIter->rowInfo.suid = pIter->dIter.bData.suid;
+      pIter->rowInfo.uid = pIter->dIter.bData.uid;
+      pIter->rowInfo.row = tsdbRowFromBlockData(&pIter->dIter.bData, pIter->dIter.iRow);
+      break;
+    }
+
+    for (;;) {
+      if (++pIter->dIter.iDataBlk < pIter->dIter.mDataBlk.nItem) {
+        SDataBlk dataBlk;
+        tMapDataGetItemByIdx(&pIter->dIter.mDataBlk, pIter->dIter.iDataBlk, &dataBlk, tGetDataBlk);
+
+        code = tsdbReadDataBlockEx(pIter->dIter.pReader, &dataBlk, &pIter->dIter.bData);
+        TSDB_CHECK_CODE(code, lino, _exit);
+
+        pIter->dIter.iRow = -1;
+
+        break;
+      }
+
+      for (;;) {
+        if (++pIter->dIter.iBlockIdx < taosArrayGetSize(pIter->dIter.aBlockIdx)) {
+          SBlockIdx* pBlockIdx = taosArrayGet(pIter->dIter.aBlockIdx, pIter->dIter.iBlockIdx);
+
+          code = tsdbReadDataBlk(pIter->dIter.pReader, pBlockIdx, &pIter->dIter.mDataBlk);
+          TSDB_CHECK_CODE(code, lino, _exit);
+
+          pIter->dIter.iDataBlk = -1;
+
+          break;
+        } else {
+          pIter->rowInfo = (SRowInfo){0};
+          goto _exit;
+        }
+      }
+    }
+  }
+
+_exit:
+  if (code) {
+    tsdbError("%s failed at line %d since %s", __func__, lino, tstrerror(code));
+  }
+  return code;
+}
+
+static int32_t tsdbSttFileDataIterNext(STsdbDataIter2* pIter) {
+  int32_t code = 0;
+  int32_t lino = 0;
+
+  for (;;) {
+    if (++pIter->sIter.iRow < pIter->sIter.bData.nRow) {
+      pIter->rowInfo.suid = pIter->sIter.bData.suid;
+      pIter->rowInfo.uid = pIter->sIter.bData.uid ? pIter->sIter.bData.uid : pIter->sIter.bData.aUid[pIter->sIter.iRow];
+      pIter->rowInfo.row = tsdbRowFromBlockData(&pIter->sIter.bData, pIter->sIter.iRow);
+      break;
+    }
+
+    if (++pIter->sIter.iSttBlk < taosArrayGetSize(pIter->sIter.aSttBlk)) {
+      SSttBlk* pSttBlk = taosArrayGet(pIter->sIter.aSttBlk, pIter->sIter.iSttBlk);
+
+      code = tsdbReadSttBlockEx(pIter->sIter.pReader, pIter->sIter.iStt, pSttBlk, &pIter->sIter.bData);
+      TSDB_CHECK_CODE(code, lino, _exit);
+
+      pIter->sIter.iRow = -1;
+    } else {
+      pIter->rowInfo = (SRowInfo){0};
+      break;
+    }
+  }
+
+_exit:
+  if (code) {
+    tsdbError("%s failed at line %d since %s", __func__, lino, tstrerror(code));
+  }
+  return code;
+}
+
+static int32_t tsdbDataIterNext2(STsdbDataIter2* pIter) {
+  int32_t code = 0;
+
+  if (pIter->type == TSDB_MEM_TABLE_DATA_ITER) {
+    ASSERT(0);
+    return code;
+  } else if (pIter->type == TSDB_DATA_FILE_DATA_ITER) {
+    return tsdbDataFileDataIterNext(pIter);
+  } else if (pIter->type == TSDB_STT_FILE_DATA_ITER) {
+    return tsdbSttFileDataIterNext(pIter);
+  } else {
+    ASSERT(0);
+    return code;
+  }
+}
+
+/* get */
+
 // STsdbSnapReader ========================================
 typedef enum { SNAP_DATA_FILE_ITER = 0, SNAP_STT_FILE_ITER } EFIterT;
 typedef struct {
@@ -63,8 +337,6 @@ struct STsdbSnapReader {
   uint8_t*     aBuf[5];
 };
 
-extern int32_t tRowInfoCmprFn(const void* p1, const void* p2);
-extern int32_t tsdbReadDataBlockEx(SDataFReader* pReader, SDataBlk* pDataBlk, SBlockData* pBlockData);
 extern int32_t tsdbUpdateTableSchema(SMeta* pMeta, int64_t suid, int64_t uid, SSkmInfo* pSkmInfo);
 
 static int32_t tFDataIterCmprFn(const SRBTreeNode* pNode1, const SRBTreeNode* pNode2) {
@@ -632,12 +904,9 @@ _exit:
 
 // STsdbSnapWriter ========================================
 struct STsdbSnapWriter {
-  STsdb*  pTsdb;
-  int64_t sver;
-  int64_t ever;
-  STsdbFS fs;
-
-  // config
+  STsdb*   pTsdb;
+  int64_t  sver;
+  int64_t  ever;
   int32_t  minutes;
   int8_t   precision;
   int32_t  minRow;
@@ -646,31 +915,31 @@ struct STsdbSnapWriter {
   int64_t  commitID;
   uint8_t* aBuf[5];
 
-  // for data file
-  SBlockData bData;
-  int32_t    fid;
-  TABLEID    id;
-  SSkmInfo   skmTable;
-  struct {
-    SDataFReader* pReader;
-    SArray*       aBlockIdx;
-    int32_t       iBlockIdx;
-    SBlockIdx*    pBlockIdx;
-    SMapData      mDataBlk;
-    int32_t       iDataBlk;
-    SBlockData    bData;
-    int32_t       iRow;
-  } dReader;
-  struct {
-    SDataFWriter* pWriter;
-    SArray*       aBlockIdx;
-    SMapData      mDataBlk;
-    SArray*       aSttBlk;
-    SBlockData    bData;
-    SBlockData    sData;
-  } dWriter;
+  STsdbFS fs;
 
-  // for del file
+  // time-series data
+  SBlockData inData;
+
+  int32_t  fid;
+  TABLEID  tbid;
+  SSkmInfo skmTable;
+
+  /* reader */
+  SDataFReader*   pDataFReader;
+  STsdbDataIter2* iterList;
+  STsdbDataIter2* pDIter;
+  STsdbDataIter2* pIter;
+  SRBTree         rbt;  // SRBTree<STsdbDataIter2>
+
+  /* writer */
+  SDataFWriter* pDataFWriter;
+  SArray*       aBlockIdx;
+  SMapData      mDataBlk;  // SMapData<SDataBlk>
+  SArray*       aSttBlk;   // SArray<SSttBlk>
+  SBlockData    bData;
+  SBlockData    sData;
+
+  // tombstone data
   SDelFReader* pDelFReader;
   SDelFWriter* pDelFWriter;
   int32_t      iDelIdx;
@@ -685,7 +954,9 @@ extern int32_t tsdbWriteSttBlock(SDataFWriter* pWriter, SBlockData* pBlockData,
 
 static int32_t tsdbSnapNextTableData(STsdbSnapWriter* pWriter) {
   int32_t code = 0;
+  int32_t lino = 0;
 
+#if 0
   ASSERT(pWriter->dReader.iRow >= pWriter->dReader.bData.nRow);
 
   if (pWriter->dReader.iBlockIdx < taosArrayGetSize(pWriter->dReader.aBlockIdx)) {
@@ -702,14 +973,20 @@ static int32_t tsdbSnapNextTableData(STsdbSnapWriter* pWriter) {
   pWriter->dReader.iDataBlk = 0;  // point to the next one
   tBlockDataReset(&pWriter->dReader.bData);
   pWriter->dReader.iRow = 0;
+#endif
 
 _exit:
+  if (code) {
+    tsdbError("vgId:%d %s failed at line %d since %s", TD_VID(pWriter->pTsdb->pVnode), __func__, lino, tstrerror(code));
+  }
   return code;
 }
 
 static int32_t tsdbSnapWriteCopyData(STsdbSnapWriter* pWriter, TABLEID* pId) {
   int32_t code = 0;
+  int32_t lino = 0;
 
+#if 0
   while (true) {
     if (pWriter->dReader.pBlockIdx == NULL) break;
     if (tTABLEIDCmprFn(pWriter->dReader.pBlockIdx, pId) >= 0) break;
@@ -726,37 +1003,93 @@ static int32_t tsdbSnapWriteCopyData(STsdbSnapWriter* pWriter, TABLEID* pId) {
     code = tsdbSnapNextTableData(pWriter);
     if (code) goto _exit;
   }
+#endif
 
 _exit:
+  if (code) {
+    tsdbError("vgId:%d %s failed at line %d since %s", TD_VID(pWriter->pTsdb->pVnode), __func__, lino, tstrerror(code));
+  }
   return code;
 }
 
 static int32_t tsdbSnapWriteTableDataStart(STsdbSnapWriter* pWriter, TABLEID* pId) {
   int32_t code = 0;
+  int32_t lino = 0;
+
+  if (pWriter->pDIter) {
+    STsdbDataIter2* pIter = pWriter->pDIter;
+    for (;;) {
+      if (pIter->dIter.iBlockIdx + 1 >= taosArrayGetSize(pIter->dIter.aBlockIdx)) {
+        pWriter->pDIter = NULL;
+        break;
+      }
+
+      SBlockIdx* pBlockIdx = (SBlockIdx*)taosArrayGet(pIter->dIter.aBlockIdx, pIter->dIter.iBlockIdx + 1);
+
+      int32_t c = tTABLEIDCmprFn(pBlockIdx, pId);
+      if (c < 0) {
+        ++pIter->dIter.iBlockIdx;
+
+        code = tsdbReadDataBlk(pIter->dIter.pReader, pBlockIdx, &pIter->dIter.mDataBlk);
+        TSDB_CHECK_CODE(code, lino, _exit);
+
+        SBlockIdx* pNewBlockIdx = taosArrayReserve(pWriter->aBlockIdx, 1);
+        if (pNewBlockIdx == NULL) {
+          code == TSDB_CODE_OUT_OF_MEMORY;
+          TSDB_CHECK_CODE(code, lino, _exit);
+        }
+
+        pNewBlockIdx->suid = pBlockIdx->suid;
+        pNewBlockIdx->uid = pBlockIdx->uid;
+
+        code = tsdbWriteDataBlk(pWriter->pDataFWriter, &pIter->dIter.mDataBlk, pBlockIdx);
+        TSDB_CHECK_CODE(code, lino, _exit);
+      } else if (c == 0) {
+        ++pIter->dIter.iBlockIdx;
+
+        code = tsdbReadDataBlk(pIter->dIter.pReader, pBlockIdx, &pIter->dIter.mDataBlk);
+        TSDB_CHECK_CODE(code, lino, _exit);
+
+        pIter->dIter.iDataBlk = -1;
+
+        break;
+      } else {
+        break;
+      }
+    }
+  }
 
+  pWriter->tbid = pId[0];
+
+  tMapDataReset(&pWriter->mDataBlk);
+
+#if 0
   code = tsdbSnapWriteCopyData(pWriter, pId);
-  if (code) goto _err;
+  TSDB_CHECK_CODE(code, lino, _exit);
 
   pWriter->id.suid = pId->suid;
   pWriter->id.uid = pId->uid;
 
   code = tsdbUpdateTableSchema(pWriter->pTsdb->pVnode->pMeta, pId->suid, pId->uid, &pWriter->skmTable);
-  if (code) goto _err;
+  TSDB_CHECK_CODE(code, lino, _exit);
 
   tMapDataReset(&pWriter->dWriter.mDataBlk);
   code = tBlockDataInit(&pWriter->dWriter.bData, pId, pWriter->skmTable.pTSchema, NULL, 0);
-  if (code) goto _err;
-
-  return code;
+  TSDB_CHECK_CODE(code, lino, _exit);
+#endif
 
-_err:
-  tsdbError("vgId:%d, %s failed since %s", TD_VID(pWriter->pTsdb->pVnode), __func__, tstrerror(code));
+_exit:
+  if (code) {
+    tsdbError("vgId:%d %s failed at line %d since %s", TD_VID(pWriter->pTsdb->pVnode), __func__, lino, tstrerror(code));
+  }
   return code;
 }
 
 static int32_t tsdbSnapWriteTableDataEnd(STsdbSnapWriter* pWriter) {
   int32_t code = 0;
+  int32_t lino = 0;
 
+#if 0
   if (pWriter->id.suid == 0 && pWriter->id.uid == 0) return code;
 
   int32_t c = 1;
@@ -807,123 +1140,174 @@ static int32_t tsdbSnapWriteTableDataEnd(STsdbSnapWriter* pWriter) {
 
   pWriter->id.suid = 0;
   pWriter->id.uid = 0;
+#endif
 
-  return code;
-
-_err:
+_exit:
+  if (code) {
+    tsdbError("vgId:%d %s failed at line %d since %s", TD_VID(pWriter->pTsdb->pVnode), __func__, lino, tstrerror(code));
+  }
   return code;
 }
 
-static int32_t tsdbSnapWriteOpenFile(STsdbSnapWriter* pWriter, int32_t fid) {
+static int32_t tsdbSnapWriteOpenDataFile(STsdbSnapWriter* pWriter, int32_t fid) {
   int32_t code = 0;
-  STsdb*  pTsdb = pWriter->pTsdb;
+  int32_t lino = 0;
+
+  ASSERT(pWriter->pDataFWriter == NULL && pWriter->fid < fid);
 
-  ASSERT(pWriter->dWriter.pWriter == NULL);
+  STsdb* pTsdb = pWriter->pTsdb;
 
   pWriter->fid = fid;
-  pWriter->id = (TABLEID){0};
+  pWriter->tbid = (TABLEID){0};
   SDFileSet* pSet = taosArraySearch(pWriter->fs.aDFileSet, &(SDFileSet){.fid = fid}, tDFileSetCmprFn, TD_EQ);
 
-  // Reader
+  // open reader
+  pWriter->pDataFReader = NULL;
+  pWriter->iterList = NULL;
+  pWriter->pDIter = NULL;
+  pWriter->pIter = NULL;
+  tRBTreeCreate(&pWriter->rbt, tsdbDataIterCmprFn);
   if (pSet) {
-    code = tsdbDataFReaderOpen(&pWriter->dReader.pReader, pWriter->pTsdb, pSet);
-    if (code) goto _err;
+    code = tsdbDataFReaderOpen(&pWriter->pDataFReader, pTsdb, pSet);
+    TSDB_CHECK_CODE(code, lino, _exit);
 
-    code = tsdbReadBlockIdx(pWriter->dReader.pReader, pWriter->dReader.aBlockIdx);
-    if (code) goto _err;
-  } else {
-    ASSERT(pWriter->dReader.pReader == NULL);
-    taosArrayClear(pWriter->dReader.aBlockIdx);
-  }
-  pWriter->dReader.iBlockIdx = 0;  // point to the next one
-  code = tsdbSnapNextTableData(pWriter);
-  if (code) goto _err;
+    code = tsdbOpenDataFileDataIter(pWriter->pDataFReader, &pWriter->pDIter);
+    TSDB_CHECK_CODE(code, lino, _exit);
+    if (pWriter->pDIter) {
+      pWriter->pDIter->next = pWriter->iterList;
+      pWriter->iterList = pWriter->pDIter;
+    }
 
-  // Writer
-  SHeadFile fHead = {.commitID = pWriter->commitID};
-  SDataFile fData = {.commitID = pWriter->commitID};
-  SSmaFile  fSma = {.commitID = pWriter->commitID};
-  SSttFile  fStt = {.commitID = pWriter->commitID};
-  SDFileSet wSet = {.fid = pWriter->fid, .pHeadF = &fHead, .pDataF = &fData, .pSmaF = &fSma};
-  if (pSet) {
-    wSet.diskId = pSet->diskId;
-    fData = *pSet->pDataF;
-    fSma = *pSet->pSmaF;
     for (int32_t iStt = 0; iStt < pSet->nSttF; iStt++) {
-      wSet.aSttF[iStt] = pSet->aSttF[iStt];
+      code = tsdbOpenSttFileDataIter(pWriter->pDataFReader, iStt, &pWriter->pIter);
+      TSDB_CHECK_CODE(code, lino, _exit);
+
+      if (pWriter->pIter) {
+        code = tsdbSttFileDataIterNext(pWriter->pIter);
+        TSDB_CHECK_CODE(code, lino, _exit);
+
+        // add to tree
+        tRBTreePut(&pWriter->rbt, &pWriter->pIter->rbtn);
+
+        // add to list
+        pWriter->pIter->next = pWriter->iterList;
+        pWriter->iterList = pWriter->pIter;
+      }
     }
-    wSet.nSttF = pSet->nSttF + 1;  // TODO: fix pSet->nSttF == pTsdb->maxFile
+
+    pWriter->pIter = NULL;
+  }
+
+  // open writer
+  SDiskID diskId;
+  if (pSet) {
+    diskId = pSet->diskId;
   } else {
-    SDiskID did = {0};
-    tfsAllocDisk(pTsdb->pVnode->pTfs, 0, &did);
-    tfsMkdirRecurAt(pTsdb->pVnode->pTfs, pTsdb->path, did);
-    wSet.diskId = did;
-    wSet.nSttF = 1;
+    tfsAllocDisk(pTsdb->pVnode->pTfs, 0 /*TODO*/, &diskId);
+    tfsMkdirRecurAt(pTsdb->pVnode->pTfs, pTsdb->path, diskId);
+  }
+  SDFileSet wSet = {.diskId = diskId,
+                    .fid = fid,
+                    .pHeadF = &(SHeadFile){.commitID = pWriter->commitID},
+                    .pDataF = (pSet) ? pSet->pDataF : &(SDataFile){.commitID = pWriter->commitID},
+                    .pSmaF = (pSet) ? pSet->pSmaF : &(SSmaFile){.commitID = pWriter->commitID},
+                    .nSttF = 1,
+                    .aSttF = {&(SSttFile){.commitID = pWriter->commitID}}};
+  code = tsdbDataFWriterOpen(&pWriter->pDataFWriter, pTsdb, &wSet);
+  TSDB_CHECK_CODE(code, lino, _exit);
+
+  if (pWriter->aBlockIdx) {
+    taosArrayClear(pWriter->aBlockIdx);
+  } else if ((pWriter->aBlockIdx = taosArrayInit(0, sizeof(SBlockIdx))) == NULL) {
+    code = TSDB_CODE_OUT_OF_MEMORY;
+    TSDB_CHECK_CODE(code, lino, _exit);
   }
-  wSet.aSttF[wSet.nSttF - 1] = &fStt;
 
-  code = tsdbDataFWriterOpen(&pWriter->dWriter.pWriter, pWriter->pTsdb, &wSet);
-  if (code) goto _err;
-  taosArrayClear(pWriter->dWriter.aBlockIdx);
-  tMapDataReset(&pWriter->dWriter.mDataBlk);
-  taosArrayClear(pWriter->dWriter.aSttBlk);
-  tBlockDataReset(&pWriter->dWriter.bData);
-  tBlockDataReset(&pWriter->dWriter.sData);
+  tMapDataReset(&pWriter->mDataBlk);
 
-  return code;
+  if (pWriter->aSttBlk) {
+    taosArrayClear(pWriter->aSttBlk);
+  } else if ((pWriter->aSttBlk = taosArrayInit(0, sizeof(SSttBlk))) == NULL) {
+    code = TSDB_CODE_OUT_OF_MEMORY;
+    TSDB_CHECK_CODE(code, lino, _exit);
+  }
 
-_err:
+  tBlockDataReset(&pWriter->bData);
+
+_exit:
+  if (code) {
+    tsdbError("vgId:%d %s failed at line %d since %s, fid:%d", TD_VID(pTsdb->pVnode), __func__, lino, tstrerror(code),
+              fid);
+  } else {
+    tsdbDebug("vgId:%d %s done, fid:%d", TD_VID(pTsdb->pVnode), __func__, fid);
+  }
   return code;
 }
 
-static int32_t tsdbSnapWriteCloseFile(STsdbSnapWriter* pWriter) {
+static int32_t tsdbSnapWriteCloseDataFile(STsdbSnapWriter* pWriter) {
   int32_t code = 0;
+  int32_t lino = 0;
 
-  ASSERT(pWriter->dWriter.pWriter);
+  ASSERT(pWriter->pDataFWriter);
 
-  code = tsdbSnapWriteTableDataEnd(pWriter);
-  if (code) goto _err;
+#if 0
+  // loop write remain data
+  for (;;) {
+    SRowInfo* pRowInfo;
 
-  // copy remain table data
-  TABLEID id = {.suid = INT64_MAX, .uid = INT64_MAX};
-  code = tsdbSnapWriteCopyData(pWriter, &id);
-  if (code) goto _err;
+    code = tsdbSnapWriteGetRow(pWriter, &pRowInfo);
+    TSDB_CHECK_CODE(code, lino, _exit);
 
-  code =
-      tsdbWriteSttBlock(pWriter->dWriter.pWriter, &pWriter->dWriter.sData, pWriter->dWriter.aSttBlk, pWriter->cmprAlg);
-  if (code) goto _err;
+    if (pRowInfo == NULL) break;
 
-  // Indices
-  code = tsdbWriteBlockIdx(pWriter->dWriter.pWriter, pWriter->dWriter.aBlockIdx);
-  if (code) goto _err;
+    code = tsdbSnapWriteTableData(pWriter, pRowInfo);
+    TSDB_CHECK_CODE(code, lino, _exit);
 
-  code = tsdbWriteSttBlk(pWriter->dWriter.pWriter, pWriter->dWriter.aSttBlk);
-  if (code) goto _err;
+    code = tsdbSnapWriteNextRow(pWriter);
+    TSDB_CHECK_CODE(code, lino, _exit);
+  }
 
-  code = tsdbUpdateDFileSetHeader(pWriter->dWriter.pWriter);
-  if (code) goto _err;
+  // TODO: write remain data
+#endif
 
-  code = tsdbFSUpsertFSet(&pWriter->fs, &pWriter->dWriter.pWriter->wSet);
-  if (code) goto _err;
+  // do file-level updates
+  code = tsdbWriteSttBlk(pWriter->pDataFWriter, pWriter->aSttBlk);
+  TSDB_CHECK_CODE(code, lino, _exit);
 
-  code = tsdbDataFWriterClose(&pWriter->dWriter.pWriter, 1);
-  if (code) goto _err;
+  code = tsdbWriteBlockIdx(pWriter->pDataFWriter, pWriter->aBlockIdx);
+  TSDB_CHECK_CODE(code, lino, _exit);
 
-  if (pWriter->dReader.pReader) {
-    code = tsdbDataFReaderClose(&pWriter->dReader.pReader);
-    if (code) goto _err;
+  code = tsdbUpdateDFileSetHeader(pWriter->pDataFWriter);
+  TSDB_CHECK_CODE(code, lino, _exit);
+
+  code = tsdbFSUpsertFSet(&pWriter->fs, &pWriter->pDataFWriter->wSet);
+  TSDB_CHECK_CODE(code, lino, _exit);
+
+  code = tsdbDataFWriterClose(&pWriter->pDataFWriter, 1);
+  TSDB_CHECK_CODE(code, lino, _exit);
+
+  if (pWriter->pDataFReader) {
+    code = tsdbDataFReaderClose(&pWriter->pDataFReader);
+    TSDB_CHECK_CODE(code, lino, _exit);
   }
 
-_exit:
-  return code;
+  // TODO: do clear sources
+  {}
 
-_err:
+_exit:
+  if (code) {
+    tsdbError("vgId:%d %s failed since %s", TD_VID(pWriter->pTsdb->pVnode), __func__, tstrerror(code));
+  } else {
+    tsdbDebug("vgId:%d %s is done", TD_VID(pWriter->pTsdb->pVnode), __func__);
+  }
   return code;
 }
 
 static int32_t tsdbSnapWriteToDataFile(STsdbSnapWriter* pWriter, int32_t iRow, int8_t* done) {
   int32_t code = 0;
+  int32_t lino = 0;
 
+#if 0
   SBlockData* pBData = &pWriter->bData;
   TABLEID     id = {.suid = pBData->suid, .uid = pBData->uid ? pBData->uid : pBData->aUid[iRow]};
   TSDBROW     row = tsdbRowFromBlockData(pBData, iRow);
@@ -942,10 +1326,10 @@ static int32_t tsdbSnapWriteToDataFile(STsdbSnapWriter* pWriter, int32_t iRow, i
       int32_t c = tsdbKeyCmprFn(&key, &tKey);
       if (c < 0) {
         code = tBlockDataAppendRow(&pWriter->dWriter.bData, &row, NULL, id.uid);
-        if (code) goto _err;
+        TSDB_CHECK_CODE(code, lino, _exit);
       } else if (c > 0) {
         code = tBlockDataAppendRow(&pWriter->dWriter.bData, &trow, NULL, id.uid);
-        if (code) goto _err;
+        TSDB_CHECK_CODE(code, lino, _exit);
       } else {
         ASSERT(0);
       }
@@ -953,7 +1337,7 @@ static int32_t tsdbSnapWriteToDataFile(STsdbSnapWriter* pWriter, int32_t iRow, i
       if (pWriter->dWriter.bData.nRow >= pWriter->maxRow) {
         code = tsdbWriteDataBlock(pWriter->dWriter.pWriter, &pWriter->dWriter.bData, &pWriter->dWriter.mDataBlk,
                                   pWriter->cmprAlg);
-        if (code) goto _err;
+        TSDB_CHECK_CODE(code, lino, _exit);
       }
 
       if (c < 0) {
@@ -972,25 +1356,25 @@ static int32_t tsdbSnapWriteToDataFile(STsdbSnapWriter* pWriter, int32_t iRow, i
       if (c < 0) {
         code = tsdbWriteDataBlock(pWriter->dWriter.pWriter, &pWriter->dWriter.bData, &pWriter->dWriter.mDataBlk,
                                   pWriter->cmprAlg);
-        if (code) goto _err;
+        TSDB_CHECK_CODE(code, lino, _exit);
 
         code = tMapDataPutItem(&pWriter->dWriter.mDataBlk, &dataBlk, tPutDataBlk);
-        if (code) goto _err;
+        TSDB_CHECK_CODE(code, lino, _exit);
       } else if (c > 0) {
         code = tBlockDataAppendRow(&pWriter->dWriter.bData, &row, NULL, id.uid);
-        if (code) goto _err;
+        TSDB_CHECK_CODE(code, lino, _exit);
 
         if (pWriter->dWriter.bData.nRow >= pWriter->maxRow) {
           code = tsdbWriteDataBlock(pWriter->dWriter.pWriter, &pWriter->dWriter.bData, &pWriter->dWriter.mDataBlk,
                                     pWriter->cmprAlg);
-          if (code) goto _err;
+          TSDB_CHECK_CODE(code, lino, _exit);
         }
 
         *done = 1;
         goto _exit;
       } else {
         code = tsdbReadDataBlockEx(pWriter->dReader.pReader, &dataBlk, &pWriter->dReader.bData);
-        if (code) goto _err;
+        TSDB_CHECK_CODE(code, lino, _exit);
         pWriter->dReader.iRow = 0;
 
         pWriter->dReader.iDataBlk++;
@@ -998,18 +1382,20 @@ static int32_t tsdbSnapWriteToDataFile(STsdbSnapWriter* pWriter, int32_t iRow, i
       }
     }
   }
+#endif
 
 _exit:
-  return code;
-
-_err:
-  tsdbError("vgId:%d, %s failed since %s", TD_VID(pWriter->pTsdb->pVnode), __func__, tstrerror(code));
+  if (code) {
+    tsdbError("vgId:%d %s failed at line %d since %s", TD_VID(pWriter->pTsdb->pVnode), __func__, lino, tstrerror(code));
+  }
   return code;
 }
 
 static int32_t tsdbSnapWriteToSttFile(STsdbSnapWriter* pWriter, int32_t iRow) {
   int32_t code = 0;
+  int32_t lino = 0;
 
+#if 0
   TABLEID     id = {.suid = pWriter->bData.suid,
                     .uid = pWriter->bData.uid ? pWriter->bData.uid : pWriter->bData.aUid[iRow]};
   TSDBROW     row = tsdbRowFromBlockData(&pWriter->bData, iRow);
@@ -1017,8 +1403,8 @@ static int32_t tsdbSnapWriteToSttFile(STsdbSnapWriter* pWriter, int32_t iRow) {
 
   if (pBData->suid || pBData->uid) {
     if (!TABLE_SAME_SCHEMA(pBData->suid, pBData->uid, id.suid, id.uid)) {
-      code = tsdbWriteSttBlock(pWriter->dWriter.pWriter, pBData, pWriter->dWriter.aSttBlk, pWriter->cmprAlg);
-      if (code) goto _err;
+      code = tsdbWriteSttBlock(pWriter->pDataFWriter, pBData, pWriter->aSttBlk, pWriter->cmprAlg);
+      TSDB_CHECK_CODE(code, lino, _exit);
 
       pBData->suid = 0;
       pBData->uid = 0;
@@ -1027,105 +1413,263 @@ static int32_t tsdbSnapWriteToSttFile(STsdbSnapWriter* pWriter, int32_t iRow) {
 
   if (pBData->suid == 0 && pBData->uid == 0) {
     code = tsdbUpdateTableSchema(pWriter->pTsdb->pVnode->pMeta, pWriter->id.suid, pWriter->id.uid, &pWriter->skmTable);
-    if (code) goto _err;
+    TSDB_CHECK_CODE(code, lino, _exit);
 
     TABLEID tid = {.suid = pWriter->id.suid, .uid = pWriter->id.suid ? 0 : pWriter->id.uid};
     code = tBlockDataInit(pBData, &tid, pWriter->skmTable.pTSchema, NULL, 0);
-    if (code) goto _err;
+    TSDB_CHECK_CODE(code, lino, _exit);
   }
 
   code = tBlockDataAppendRow(pBData, &row, NULL, id.uid);
-  if (code) goto _err;
+  TSDB_CHECK_CODE(code, lino, _exit);
 
   if (pBData->nRow >= pWriter->maxRow) {
-    code = tsdbWriteSttBlock(pWriter->dWriter.pWriter, pBData, pWriter->dWriter.aSttBlk, pWriter->cmprAlg);
-    if (code) goto _err;
+    code = tsdbWriteSttBlock(pWriter->pDataFWriter, pBData, pWriter->aSttBlk, pWriter->cmprAlg);
+    TSDB_CHECK_CODE(code, lino, _exit);
   }
+#endif
 
 _exit:
-  return code;
-
-_err:
+  if (code) {
+    tsdbError("vgId:%d %s failed since %s", TD_VID(pWriter->pTsdb->pVnode), __func__, tstrerror(code));
+  }
   return code;
 }
 
-static int32_t tsdbSnapWriteRowData(STsdbSnapWriter* pWriter, int32_t iRow) {
+static int32_t tsdbSnapWriteNextRow(STsdbSnapWriter* pWriter, SRowInfo** ppRowInfo) {
   int32_t code = 0;
+  int32_t lino = 0;
 
-  SBlockData* pBlockData = &pWriter->bData;
-  TABLEID     id = {.suid = pBlockData->suid, .uid = pBlockData->uid ? pBlockData->uid : pBlockData->aUid[iRow]};
+  if (pWriter->pIter) {
+    code = tsdbDataIterNext2(pWriter->pIter);
+    TSDB_CHECK_CODE(code, lino, _exit);
 
-  // End last table data write if need
-  if (tTABLEIDCmprFn(&pWriter->id, &id) != 0) {
-    code = tsdbSnapWriteTableDataEnd(pWriter);
-    if (code) goto _err;
+    if (pWriter->pIter->rowInfo.suid == 0 && pWriter->pIter->rowInfo.uid == 0) {
+      pWriter->pIter = NULL;
+    } else {
+      SRBTreeNode* pNode = tRBTreeMin(&pWriter->rbt);
+      if (pNode) {
+        int32_t c = tsdbDataIterCmprFn(&pWriter->pIter->rbtn, pNode);
+        if (c > 0) {
+          tRBTreePut(&pWriter->rbt, &pWriter->pIter->rbtn);
+          pWriter->pIter = NULL;
+        } else if (c == 0) {
+          ASSERT(0);
+        }
+      }
+    }
   }
 
-  // Start new table data write if need
-  if (pWriter->id.suid == 0 && pWriter->id.uid == 0) {
-    code = tsdbSnapWriteTableDataStart(pWriter, &id);
-    if (code) goto _err;
+  if (pWriter->pIter == NULL) {
+    SRBTreeNode* pNode = tRBTreeMin(&pWriter->rbt);
+    if (pNode) {
+      tRBTreeDrop(&pWriter->rbt, pNode);
+      pWriter->pIter = TSDB_RBTN_TO_DATA_ITER(pNode);
+    }
   }
 
-  // Merge with .data file data
-  int8_t done = 0;
-  if (pWriter->dReader.pBlockIdx && tTABLEIDCmprFn(pWriter->dReader.pBlockIdx, &id) == 0) {
-    code = tsdbSnapWriteToDataFile(pWriter, iRow, &done);
-    if (code) goto _err;
+  if (ppRowInfo) {
+    if (pWriter->pIter) {
+      *ppRowInfo = &pWriter->pIter->rowInfo;
+    } else {
+      *ppRowInfo = NULL;
+    }
   }
 
-  // Append to the .stt data block (todo: check if need to set/reload sst block)
-  if (!done) {
-    code = tsdbSnapWriteToSttFile(pWriter, iRow);
-    if (code) goto _err;
+_exit:
+  if (code) {
+    tsdbError("vgId:%d %s failed at line %d since %s", TD_VID(pWriter->pTsdb->pVnode), __func__, lino, tstrerror(code));
   }
+  return code;
+}
+
+static int32_t tsdbSnapWriteGetRow(STsdbSnapWriter* pWriter, SRowInfo** ppRowInfo) {
+  int32_t code = 0;
+  int32_t lino = 0;
+
+  if (pWriter->pIter) {
+    *ppRowInfo = &pWriter->pIter->rowInfo;
+    goto _exit;
+  }
+
+  code = tsdbSnapWriteNextRow(pWriter, ppRowInfo);
+  TSDB_CHECK_CODE(code, lino, _exit);
 
 _exit:
+  if (code) {
+    tsdbError("vgId:%d %s failed at line %d since %s", TD_VID(pWriter->pTsdb->pVnode), __func__, lino, tstrerror(code));
+  }
   return code;
+}
 
-_err:
-  tsdbError("vgId:%d, %s failed since %s", TD_VID(pWriter->pTsdb->pVnode), __func__, tstrerror(code));
+static int32_t tsdbSnapWriteRowImpl(STsdbSnapWriter* pWriter, SRowInfo* pRowInfo) {
+  int32_t code = 0;
+  int32_t lino = 0;
+
+  // TODO
+  ASSERT(0);
+
+_exit:
+  if (code) {
+    tsdbError("vgId:%d %s failed at line %d since %s", TD_VID(pWriter->pTsdb->pVnode), __func__, lino, tstrerror(code));
+  }
   return code;
 }
 
-static int32_t tsdbSnapWriteData(STsdbSnapWriter* pWriter, uint8_t* pData, uint32_t nData) {
-  int32_t     code = 0;
-  STsdb*      pTsdb = pWriter->pTsdb;
-  SBlockData* pBlockData = &pWriter->bData;
+static int32_t tsdbSnapWriteTableRow(STsdbSnapWriter* pWriter, TSDBROW* pRow) {
+  int32_t code = 0;
+  int32_t lino = 0;
 
-  // Decode data
-  SSnapDataHdr* pHdr = (SSnapDataHdr*)pData;
-  code = tDecmprBlockData(pHdr->data, pHdr->size, pBlockData, pWriter->aBuf);
-  if (code) goto _err;
+  code = tBlockDataAppendRow(&pWriter->bData, pRow, NULL, pWriter->tbid.uid);
+  TSDB_CHECK_CODE(code, lino, _exit);
+
+  if (pWriter->bData.nRow >= pWriter->maxRow) {
+    code = tsdbWriteDataBlock(pWriter->pDataFWriter, &pWriter->bData, &pWriter->mDataBlk, pWriter->cmprAlg);
+    TSDB_CHECK_CODE(code, lino, _exit);
+  }
+
+_exit:
+  if (code) {
+    tsdbError("vgId:%d %s failed at line %d since %s", TD_VID(pWriter->pTsdb->pVnode), __func__, lino, tstrerror(code));
+  }
+  return code;
+}
 
-  ASSERT(pBlockData->nRow > 0);
+static int32_t tsdbSnapWriteTableData(STsdbSnapWriter* pWriter, SRowInfo* pRowInfo) {
+  int32_t code = 0;
+  int32_t lino = 0;
 
-  // Loop to handle each row
-  for (int32_t iRow = 0; iRow < pBlockData->nRow; iRow++) {
-    TSKEY   ts = pBlockData->aTSKEY[iRow];
-    int32_t fid = tsdbKeyFid(ts, pWriter->minutes, pWriter->precision);
+  // switch to new table if need
+  if (pRowInfo->uid != pWriter->tbid.uid) {
+    if (pRowInfo->uid) {
+      code = tsdbSnapWriteTableDataEnd(pWriter);
+      TSDB_CHECK_CODE(code, lino, _exit);
+    }
 
-    if (pWriter->dWriter.pWriter == NULL || pWriter->fid != fid) {
-      if (pWriter->dWriter.pWriter) {
-        // ASSERT(fid > pWriter->fid);
+    code = tsdbSnapWriteTableDataStart(pWriter, (TABLEID*)pRowInfo);
+    TSDB_CHECK_CODE(code, lino, _exit);
+  }
 
-        code = tsdbSnapWriteCloseFile(pWriter);
-        if (code) goto _err;
+  // do write the row
+  if (pWriter->pDIter == NULL /* || false */) {
+    goto _write_incoming_row;
+  } else {
+    for (;;) {
+      while (pWriter->pDIter->dIter.iRow + 1 < pWriter->pDIter->dIter.bData.nRow) {
+        TSDBROW row = tsdbRowFromBlockData(&pWriter->pDIter->dIter.bData, pWriter->pDIter->dIter.iRow + 1);
+
+        int32_t c = tsdbRowCmprFn(&pRowInfo->row, &row);
+        if (c < 0) {
+          goto _write_incoming_row;
+        } else if (c > 0) {
+          ++pWriter->pDIter->dIter.iRow;
+
+          code = tsdbSnapWriteTableRow(pWriter, &row);
+          TSDB_CHECK_CODE(code, lino, _exit);
+        } else {
+          ASSERT(0);
+        }
       }
 
-      code = tsdbSnapWriteOpenFile(pWriter, fid);
-      if (code) goto _err;
-    }
+      while (pWriter->pDIter->dIter.iDataBlk < pWriter->pDIter->dIter.mDataBlk.nItem) {
+        SDataBlk dataBlk;
 
-    code = tsdbSnapWriteRowData(pWriter, iRow);
-    if (code) goto _err;
+        tMapDataGetItemByIdx(&pWriter->pDIter->dIter.mDataBlk, pWriter->pDIter->dIter.iDataBlk + 1, &dataBlk,
+                             tGetDataBlk);
+
+        int32_t c = tDataBlkCmprFn(
+            &dataBlk, &(SDataBlk){.minKey = TSDBROW_KEY(&pRowInfo->row), .maxKey = TSDBROW_KEY(&pRowInfo->row)});
+        if (c > 0) {
+          goto _write_incoming_row;
+        } else if (c < 0) {
+          ++pWriter->pDIter->dIter.iDataBlk;
+          tMapDataPutItem(&pWriter->pDIter->dIter.mDataBlk, &dataBlk, tPutDataBlk);
+        } else {
+          ++pWriter->pDIter->dIter.iDataBlk;
+
+          code = tsdbReadDataBlockEx(pWriter->pDataFReader, &dataBlk, &pWriter->pDIter->dIter.bData);
+          TSDB_CHECK_CODE(code, lino, _exit);
+
+          pWriter->pDIter->dIter.iRow = -1;
+          break;
+        }
+      }
+    }
   }
 
+_write_incoming_row:
+  code = tsdbSnapWriteTableRow(pWriter, &pRowInfo->row);
+  TSDB_CHECK_CODE(code, lino, _exit);
+
+_exit:
+  if (code) {
+    tsdbError("vgId:%d %s failed at line %d since %s", TD_VID(pWriter->pTsdb->pVnode), __func__, lino, tstrerror(code));
+  }
   return code;
+}
 
-_err:
-  tsdbError("vgId:%d, vnode snapshot tsdb write data for %s failed since %s", TD_VID(pTsdb->pVnode), pTsdb->path,
-            tstrerror(code));
+static int32_t tsdbSnapWriteTimeSeriesData(STsdbSnapWriter* pWriter, SSnapDataHdr* pHdr) {
+  int32_t code = 0;
+  int32_t lino = 0;
+
+  code = tDecmprBlockData(pHdr->data, pHdr->size, &pWriter->inData, pWriter->aBuf);
+  TSDB_CHECK_CODE(code, lino, _exit);
+
+  ASSERT(pWriter->inData.nRow > 0);
+
+  // switch to new data file if need
+  int32_t fid = tsdbKeyFid(pWriter->inData.aTSKEY[0], pWriter->minutes, pWriter->precision);
+  if (pWriter->fid != fid) {
+    if (pWriter->pDataFWriter) {
+      code = tsdbSnapWriteCloseDataFile(pWriter);
+      TSDB_CHECK_CODE(code, lino, _exit);
+    }
+
+    code = tsdbSnapWriteOpenDataFile(pWriter, fid);
+    TSDB_CHECK_CODE(code, lino, _exit);
+  }
+
+  // loop write each row
+  SRowInfo* pRowInfo;
+
+  code = tsdbSnapWriteGetRow(pWriter, &pRowInfo);
+  TSDB_CHECK_CODE(code, lino, _exit);
+  for (int32_t iRow = 0; iRow < pWriter->bData.nRow; ++iRow) {
+    SRowInfo rInfo = {.suid = pWriter->inData.suid,
+                      .uid = pWriter->inData.uid ? pWriter->inData.uid : pWriter->inData.aUid[iRow],
+                      .row = tsdbRowFromBlockData(&pWriter->inData, iRow)};
+
+    for (;;) {
+      if (pRowInfo == NULL) {
+        code = tsdbSnapWriteTableData(pWriter, &rInfo);
+        TSDB_CHECK_CODE(code, lino, _exit);
+        break;
+      } else {
+        int32_t c = tRowInfoCmprFn(&rInfo, pRowInfo);
+        if (c < 0) {
+          code = tsdbSnapWriteTableData(pWriter, &rInfo);
+          TSDB_CHECK_CODE(code, lino, _exit);
+          break;
+        } else if (c > 0) {
+          code = tsdbSnapWriteTableData(pWriter, pRowInfo);
+          TSDB_CHECK_CODE(code, lino, _exit);
+
+          code = tsdbSnapWriteNextRow(pWriter, &pRowInfo);
+          TSDB_CHECK_CODE(code, lino, _exit);
+        } else {
+          ASSERT(0);
+        }
+      }
+    }
+  }
+
+_exit:
+  if (code) {
+    tsdbError("vgId:%d %s failed at line %d since %s", TD_VID(pWriter->pTsdb->pVnode), __func__, lino, tstrerror(code));
+  } else {
+    tsdbDebug("vgId:%d %s done, suid:%" PRId64 " uid:%" PRId64 " nRow:%d", TD_VID(pWriter->pTsdb->pVnode), __func__,
+              pWriter->inData.suid, pWriter->inData.uid, pWriter->inData.nRow);
+  }
   return code;
 }
 
@@ -1159,7 +1703,7 @@ _exit:
   return code;
 }
 
-static int32_t tsdbSnapWriteDel(STsdbSnapWriter* pWriter, uint8_t* pData, uint32_t nData) {
+static int32_t tsdbSnapWriteDelData(STsdbSnapWriter* pWriter, SSnapDataHdr* pHdr) {
   int32_t code = 0;
   STsdb*  pTsdb = pWriter->pTsdb;
 
@@ -1186,10 +1730,7 @@ static int32_t tsdbSnapWriteDel(STsdbSnapWriter* pWriter, uint8_t* pData, uint32
     taosArrayClear(pWriter->aDelIdxW);
   }
 
-  SSnapDataHdr* pHdr = (SSnapDataHdr*)pData;
-  TABLEID       id = *(TABLEID*)pHdr->data;
-
-  ASSERT(pHdr->size + sizeof(SSnapDataHdr) == nData);
+  TABLEID id = *(TABLEID*)pHdr->data;
 
   // Move write data < id
   code = tsdbSnapMoveWriteDelData(pWriter, &id);
@@ -1208,11 +1749,11 @@ static int32_t tsdbSnapWriteDel(STsdbSnapWriter* pWriter, uint8_t* pData, uint32
     taosArrayClear(pWriter->aDelData);
   }
 
-  int64_t n = sizeof(SSnapDataHdr) + sizeof(TABLEID);
-  while (n < nData) {
+  int64_t n = sizeof(TABLEID);
+  while (n < pHdr->size) {
     SDelData delData;
 
-    n += tGetDelData(pData + n, &delData);
+    n += tGetDelData(pHdr->data + n, &delData);
 
     if (taosArrayPush(pWriter->aDelData, &delData) == NULL) {
       code = TSDB_CODE_OUT_OF_MEMORY;
@@ -1275,12 +1816,11 @@ _err:
 
 // APIs
 int32_t tsdbSnapWriterOpen(STsdb* pTsdb, int64_t sver, int64_t ever, STsdbSnapWriter** ppWriter) {
-  int32_t          code = 0;
-  int32_t          lino = 0;
-  STsdbSnapWriter* pWriter = NULL;
+  int32_t code = 0;
+  int32_t lino = 0;
 
   // alloc
-  pWriter = (STsdbSnapWriter*)taosMemoryCalloc(1, sizeof(*pWriter));
+  STsdbSnapWriter* pWriter = (STsdbSnapWriter*)taosMemoryCalloc(1, sizeof(*pWriter));
   if (pWriter == NULL) {
     code = TSDB_CODE_OUT_OF_MEMORY;
     TSDB_CHECK_CODE(code, lino, _exit);
@@ -1288,11 +1828,6 @@ int32_t tsdbSnapWriterOpen(STsdb* pTsdb, int64_t sver, int64_t ever, STsdbSnapWr
   pWriter->pTsdb = pTsdb;
   pWriter->sver = sver;
   pWriter->ever = ever;
-
-  code = tsdbFSCopy(pTsdb, &pWriter->fs);
-  TSDB_CHECK_CODE(code, lino, _exit);
-
-  // config
   pWriter->minutes = pTsdb->keepCfg.days;
   pWriter->precision = pTsdb->keepCfg.precision;
   pWriter->minRow = pTsdb->pVnode->config.tsdbCfg.minRows;
@@ -1300,7 +1835,19 @@ int32_t tsdbSnapWriterOpen(STsdb* pTsdb, int64_t sver, int64_t ever, STsdbSnapWr
   pWriter->cmprAlg = pTsdb->pVnode->config.tsdbCfg.compression;
   pWriter->commitID = pTsdb->pVnode->state.commitID;
 
+  code = tsdbFSCopy(pTsdb, &pWriter->fs);
+  TSDB_CHECK_CODE(code, lino, _exit);
+
   // SNAP_DATA_TSDB
+#if 1
+  pWriter->fid = INT32_MIN;
+
+  code = tBlockDataCreate(&pWriter->inData);
+  TSDB_CHECK_CODE(code, lino, _exit);
+
+  code = tBlockDataCreate(&pWriter->bData);
+  TSDB_CHECK_CODE(code, lino, _exit);
+#else
   code = tBlockDataCreate(&pWriter->bData);
   TSDB_CHECK_CODE(code, lino, _exit);
 
@@ -1330,6 +1877,7 @@ int32_t tsdbSnapWriterOpen(STsdb* pTsdb, int64_t sver, int64_t ever, STsdbSnapWr
   TSDB_CHECK_CODE(code, lino, _exit);
   code = tBlockDataCreate(&pWriter->dWriter.sData);
   TSDB_CHECK_CODE(code, lino, _exit);
+#endif
 
   // SNAP_DATA_DEL
   pWriter->aDelIdxR = taosArrayInit(0, sizeof(SDelIdx));
@@ -1354,6 +1902,7 @@ _exit:
     *ppWriter = NULL;
 
     if (pWriter) {
+#if 0
       if (pWriter->aDelIdxW) taosArrayDestroy(pWriter->aDelIdxW);
       if (pWriter->aDelData) taosArrayDestroy(pWriter->aDelData);
       if (pWriter->aDelIdxR) taosArrayDestroy(pWriter->aDelIdxR);
@@ -1366,6 +1915,7 @@ _exit:
       tBlockDataDestroy(&pWriter->bData, 1);
       tsdbFSDestroy(&pWriter->fs);
       taosMemoryFree(pWriter);
+#endif
     }
   } else {
     tsdbInfo("vgId:%d, %s done", TD_VID(pTsdb->pVnode), __func__);
@@ -1376,8 +1926,8 @@ _exit:
 
 int32_t tsdbSnapWriterPrepareClose(STsdbSnapWriter* pWriter) {
   int32_t code = 0;
-  if (pWriter->dWriter.pWriter) {
-    code = tsdbSnapWriteCloseFile(pWriter);
+  if (pWriter->pDataFWriter) {
+    code = tsdbSnapWriteCloseDataFile(pWriter);
     if (code) goto _exit;
   }
 
@@ -1422,17 +1972,17 @@ int32_t tsdbSnapWriterClose(STsdbSnapWriter** ppWriter, int8_t rollback) {
 
   // SNAP_DATA_TSDB
 
-  // Writer
-  tBlockDataDestroy(&pWriter->dWriter.sData, 1);
-  tBlockDataDestroy(&pWriter->dWriter.bData, 1);
-  taosArrayDestroy(pWriter->dWriter.aSttBlk);
-  tMapDataClear(&pWriter->dWriter.mDataBlk);
-  taosArrayDestroy(pWriter->dWriter.aBlockIdx);
+  // // Writer
+  // tBlockDataDestroy(&pWriter->dWriter.sData, 1);
+  // tBlockDataDestroy(&pWriter->dWriter.bData, 1);
+  // taosArrayDestroy(pWriter->dWriter.aSttBlk);
+  // tMapDataClear(&pWriter->dWriter.mDataBlk);
+  // taosArrayDestroy(pWriter->dWriter.aBlockIdx);
 
-  // Reader
-  tBlockDataDestroy(&pWriter->dReader.bData, 1);
-  tMapDataClear(&pWriter->dReader.mDataBlk);
-  taosArrayDestroy(pWriter->dReader.aBlockIdx);
+  // // Reader
+  // tBlockDataDestroy(&pWriter->dReader.bData, 1);
+  // tMapDataClear(&pWriter->dReader.mDataBlk);
+  // taosArrayDestroy(pWriter->dReader.aBlockIdx);
 
   tBlockDataDestroy(&pWriter->bData, 1);
   tDestroyTSchema(pWriter->skmTable.pTSchema);
@@ -1453,35 +2003,32 @@ _err:
   return code;
 }
 
-int32_t tsdbSnapWrite(STsdbSnapWriter* pWriter, uint8_t* pData, uint32_t nData) {
-  int32_t       code = 0;
-  SSnapDataHdr* pHdr = (SSnapDataHdr*)pData;
+int32_t tsdbSnapWrite(STsdbSnapWriter* pWriter, SSnapDataHdr* pHdr) {
+  int32_t code = 0;
+  int32_t lino = 0;
 
-  // ts data
   if (pHdr->type == SNAP_DATA_TSDB) {
-    code = tsdbSnapWriteData(pWriter, pData, nData);
-    if (code) goto _err;
-
+    code = tsdbSnapWriteTimeSeriesData(pWriter, pHdr);
+    TSDB_CHECK_CODE(code, lino, _exit);
     goto _exit;
-  } else {
-    if (pWriter->dWriter.pWriter) {
-      code = tsdbSnapWriteCloseFile(pWriter);
-      if (code) goto _err;
-    }
+  } else if (pWriter->pDataFWriter) {
+    code = tsdbSnapWriteCloseDataFile(pWriter);
+    TSDB_CHECK_CODE(code, lino, _exit);
   }
 
-  // del data
   if (pHdr->type == SNAP_DATA_DEL) {
-    code = tsdbSnapWriteDel(pWriter, pData, nData);
-    if (code) goto _err;
+    code = tsdbSnapWriteDelData(pWriter, pHdr);
+    TSDB_CHECK_CODE(code, lino, _exit);
+    goto _exit;
   }
 
 _exit:
-  tsdbDebug("vgId:%d, tsdb snapshot write for %s succeed", TD_VID(pWriter->pTsdb->pVnode), pWriter->pTsdb->path);
-  return code;
-
-_err:
-  tsdbError("vgId:%d, tsdb snapshot write for %s failed since %s", TD_VID(pWriter->pTsdb->pVnode), pWriter->pTsdb->path,
-            tstrerror(code));
+  if (code) {
+    tsdbError("vgId:%d %s failed at line %d since %s, type:%d index:%" PRId64 " size:%" PRId64,
+              TD_VID(pWriter->pTsdb->pVnode), __func__, lino, tstrerror(code), pHdr->type, pHdr->index, pHdr->size);
+  } else {
+    tsdbDebug("vgId:%d %s done, type:%d index:%" PRId64 " size:%" PRId64, TD_VID(pWriter->pTsdb->pVnode), __func__,
+              pHdr->type, pHdr->index, pHdr->size);
+  }
   return code;
 }
diff --git a/source/dnode/vnode/src/tsdb/tsdbUtil.c b/source/dnode/vnode/src/tsdb/tsdbUtil.c
index 86adc1dc8005d2233b1da39fe4f70ff7e61d43a8..10b3ef85625668cf960f5fedf240dcddcddac9ca 100644
--- a/source/dnode/vnode/src/tsdb/tsdbUtil.c
+++ b/source/dnode/vnode/src/tsdb/tsdbUtil.c
@@ -684,7 +684,7 @@ int32_t tRowMergerInit2(SRowMerger *pMerger, STSchema *pResTSchema, TSDBROW *pRo
     tsdbRowGetColVal(pRow, pTSchema, jCol++, pColVal);
     if ((!COL_VAL_IS_NONE(pColVal)) && (!COL_VAL_IS_NULL(pColVal)) && IS_VAR_DATA_TYPE(pColVal->type)) {
       uint8_t *pVal = pColVal->value.pData;
-    
+
       pColVal->value.pData = NULL;
       code = tRealloc(&pColVal->value.pData, pColVal->value.nData);
       if (code) goto _exit;
@@ -753,7 +753,7 @@ int32_t tRowMergerAdd(SRowMerger *pMerger, TSDBROW *pRow, STSchema *pTSchema) {
           code = tRealloc(&tColVal->value.pData, pColVal->value.nData);
           if (code) return code;
 
-          tColVal->value.nData = pColVal->value.nData;        
+          tColVal->value.nData = pColVal->value.nData;
           if (pColVal->value.nData) {
             memcpy(tColVal->value.pData, pColVal->value.pData, pColVal->value.nData);
           }
@@ -802,7 +802,7 @@ int32_t tRowMergerInit(SRowMerger *pMerger, TSDBROW *pRow, STSchema *pTSchema) {
     tsdbRowGetColVal(pRow, pTSchema, iCol, pColVal);
     if ((!COL_VAL_IS_NONE(pColVal)) && (!COL_VAL_IS_NULL(pColVal)) && IS_VAR_DATA_TYPE(pColVal->type)) {
       uint8_t *pVal = pColVal->value.pData;
-    
+
       pColVal->value.pData = NULL;
       code = tRealloc(&pColVal->value.pData, pColVal->value.nData);
       if (code) goto _exit;
@@ -811,7 +811,7 @@ int32_t tRowMergerInit(SRowMerger *pMerger, TSDBROW *pRow, STSchema *pTSchema) {
         memcpy(pColVal->value.pData, pVal, pColVal->value.nData);
       }
     }
-    
+
     if (taosArrayPush(pMerger->pArray, pColVal) == NULL) {
       code = TSDB_CODE_OUT_OF_MEMORY;
       goto _exit;
@@ -822,7 +822,7 @@ _exit:
   return code;
 }
 
-void tRowMergerClear(SRowMerger *pMerger) { 
+void tRowMergerClear(SRowMerger *pMerger) {
   for (int32_t iCol = 1; iCol < pMerger->pTSchema->numOfCols; iCol++) {
     SColVal *pTColVal = taosArrayGet(pMerger->pArray, iCol);
     if (IS_VAR_DATA_TYPE(pTColVal->type)) {
@@ -830,7 +830,7 @@ void tRowMergerClear(SRowMerger *pMerger) {
     }
   }
 
-  taosArrayDestroy(pMerger->pArray); 
+  taosArrayDestroy(pMerger->pArray);
 }
 
 int32_t tRowMerge(SRowMerger *pMerger, TSDBROW *pRow) {
@@ -853,7 +853,7 @@ int32_t tRowMerge(SRowMerger *pMerger, TSDBROW *pRow) {
 
             pTColVal->value.nData = pColVal->value.nData;
             if (pTColVal->value.nData) {
-              memcpy(pTColVal->value.pData,  pColVal->value.pData, pTColVal->value.nData);
+              memcpy(pTColVal->value.pData, pColVal->value.pData, pTColVal->value.nData);
             }
             pTColVal->flag = 0;
           } else {
@@ -875,7 +875,7 @@ int32_t tRowMerge(SRowMerger *pMerger, TSDBROW *pRow) {
 
             tColVal->value.nData = pColVal->value.nData;
             if (tColVal->value.nData) {
-              memcpy(tColVal->value.pData,  pColVal->value.pData, tColVal->value.nData);
+              memcpy(tColVal->value.pData, pColVal->value.pData, tColVal->value.nData);
             }
             tColVal->flag = 0;
           } else {
diff --git a/source/dnode/vnode/src/vnd/vnodeSnapshot.c b/source/dnode/vnode/src/vnd/vnodeSnapshot.c
index e75dc24329c03ade45e12242fd70a62b963f74ff..43f903dc4867178919e3d3b519b899afcca6d835 100644
--- a/source/dnode/vnode/src/vnd/vnodeSnapshot.c
+++ b/source/dnode/vnode/src/vnd/vnodeSnapshot.c
@@ -455,7 +455,7 @@ int32_t vnodeSnapWrite(SVSnapWriter *pWriter, uint8_t *pData, uint32_t nData) {
         if (code) goto _err;
       }
 
-      code = tsdbSnapWrite(pWriter->pTsdbSnapWriter, pData, nData);
+      code = tsdbSnapWrite(pWriter->pTsdbSnapWriter, pHdr);
       if (code) goto _err;
     } break;
     case SNAP_DATA_TQ_HANDLE: {