diff --git a/source/dnode/vnode/src/inc/tsdb.h b/source/dnode/vnode/src/inc/tsdb.h
index 30a6188db0..d465ba4d9b 100644
--- a/source/dnode/vnode/src/inc/tsdb.h
+++ b/source/dnode/vnode/src/inc/tsdb.h
@@ -64,6 +64,7 @@ typedef struct STsdbFS       STsdbFS;
 typedef struct SRowMerger    SRowMerger;
 typedef struct STsdbFSState  STsdbFSState;
 typedef struct STsdbSnapHdr  STsdbSnapHdr;
+typedef struct STsdbReadSnap STsdbReadSnap;
 
 #define TSDB_MAX_SUBBLOCKS 8
 #define TSDB_FHDR_SIZE     512
@@ -188,16 +189,22 @@ bool     tsdbTbDataIterNext(STbDataIter *pIter);
 int32_t tsdbGetNRowsInTbData(STbData *pTbData);
 // tsdbFile.c ==============================================================================================
 typedef enum { TSDB_HEAD_FILE = 0, TSDB_DATA_FILE, TSDB_LAST_FILE, TSDB_SMA_FILE } EDataFileT;
-void    tsdbDataFileName(STsdb *pTsdb, SDFileSet *pDFileSet, EDataFileT ftype, char fname[]);
-bool    tsdbFileIsSame(SDFileSet *pDFileSet1, SDFileSet *pDFileSet2, EDataFileT ftype);
+
 bool    tsdbDelFileIsSame(SDelFile *pDelFile1, SDelFile *pDelFile2);
-int32_t tsdbUpdateDFileHdr(TdFilePtr pFD, SDFileSet *pSet, EDataFileT ftype);
 int32_t tsdbDFileRollback(STsdb *pTsdb, SDFileSet *pSet, EDataFileT ftype);
-int32_t tPutDataFileHdr(uint8_t *p, SDFileSet *pSet, EDataFileT ftype);
+int32_t tPutHeadFile(uint8_t *p, SHeadFile *pHeadFile);
+int32_t tPutDataFile(uint8_t *p, SDataFile *pDataFile);
+int32_t tPutLastFile(uint8_t *p, SLastFile *pLastFile);
+int32_t tPutSmaFile(uint8_t *p, SSmaFile *pSmaFile);
 int32_t tPutDelFile(uint8_t *p, SDelFile *pDelFile);
 int32_t tGetDelFile(uint8_t *p, SDelFile *pDelFile);
 int32_t tPutDFileSet(uint8_t *p, SDFileSet *pSet);
 int32_t tGetDFileSet(uint8_t *p, SDFileSet *pSet);
+
+void tsdbHeadFileName(STsdb *pTsdb, SDiskID did, int32_t fid, SHeadFile *pHeadF, char fname[]);
+void tsdbDataFileName(STsdb *pTsdb, SDiskID did, int32_t fid, SDataFile *pDataF, char fname[]);
+void tsdbLastFileName(STsdb *pTsdb, SDiskID did, int32_t fid, SLastFile *pLastF, char fname[]);
+void tsdbSmaFileName(STsdb *pTsdb, SDiskID did, int32_t fid, SSmaFile *pSmaF, char fname[]);
 // SDelFile
 void tsdbDelFileName(STsdb *pTsdb, SDelFile *pFile, char fname[]);
 // tsdbFS.c ==============================================================================================
@@ -222,8 +229,7 @@ int32_t tsdbWriteBlock(SDataFWriter *pWriter, SMapData *pMapData, uint8_t **ppBu
 int32_t tsdbWriteBlockData(SDataFWriter *pWriter, SBlockData *pBlockData, uint8_t **ppBuf1, uint8_t **ppBuf2,
                            SBlockIdx *pBlockIdx, SBlock *pBlock, int8_t cmprAlg);
 
-SDFileSet *tsdbDataFWriterGetWSet(SDataFWriter *pWriter);
-int32_t    tsdbDFileSetCopy(STsdb *pTsdb, SDFileSet *pSetFrom, SDFileSet *pSetTo);
+int32_t tsdbDFileSetCopy(STsdb *pTsdb, SDFileSet *pSetFrom, SDFileSet *pSetTo);
 // SDataFReader
 int32_t tsdbDataFReaderOpen(SDataFReader **ppReader, STsdb *pTsdb, SDFileSet *pSet);
 int32_t tsdbDataFReaderClose(SDataFReader **ppReader);
@@ -245,6 +251,9 @@ int32_t tsdbDelFReaderOpen(SDelFReader **ppReader, SDelFile *pFile, STsdb *pTsdb
 int32_t tsdbDelFReaderClose(SDelFReader **ppReader);
 int32_t tsdbReadDelData(SDelFReader *pReader, SDelIdx *pDelIdx, SArray *aDelData, uint8_t **ppBuf);
 int32_t tsdbReadDelIdx(SDelFReader *pReader, SArray *aDelIdx, uint8_t **ppBuf);
+// tsdbRead.c ==============================================================================================
+int32_t tsdbTakeReadSnap(STsdb *pTsdb, STsdbReadSnap **ppSnap);
+void    tsdbUntakeReadSnap(STsdb *pTsdb, STsdbReadSnap *pSnap);
 
 #define TSDB_CACHE_NO(c)       ((c).cacheLast == 0)
 #define TSDB_CACHE_LAST_ROW(c) (((c).cacheLast & 1) > 0)
@@ -465,12 +474,6 @@ struct SDelIdx {
   int64_t  size;
 };
 
-struct SDelFile {
-  int64_t commitID;
-  int64_t size;
-  int64_t offset;
-};
-
 #pragma pack(push, 1)
 struct SBlockDataHdr {
   uint32_t delimiter;
@@ -479,34 +482,50 @@ struct SBlockDataHdr {
 };
 #pragma pack(pop)
 
+struct SDelFile {
+  volatile int32_t nRef;
+
+  int64_t commitID;
+  int64_t size;
+  int64_t offset;
+};
+
 struct SHeadFile {
+  volatile int32_t nRef;
+
   int64_t commitID;
   int64_t size;
   int64_t offset;
 };
 
 struct SDataFile {
+  volatile int32_t nRef;
+
   int64_t commitID;
   int64_t size;
 };
 
 struct SLastFile {
+  volatile int32_t nRef;
+
   int64_t commitID;
   int64_t size;
 };
 
 struct SSmaFile {
+  volatile int32_t nRef;
+
   int64_t commitID;
   int64_t size;
 };
 
 struct SDFileSet {
-  SDiskID   diskId;
-  int32_t   fid;
-  SHeadFile fHead;
-  SDataFile fData;
-  SLastFile fLast;
-  SSmaFile  fSma;
+  SDiskID    diskId;
+  int32_t    fid;
+  SHeadFile *pHeadF;
+  SDataFile *pDataF;
+  SLastFile *pLastF;
+  SSmaFile  *pSmaF;
 };
 
 struct SRowIter {
@@ -528,11 +547,13 @@ struct STsdbFSState {
 };
 
 struct STsdbFS {
-  STsdb         *pTsdb;
-  TdThreadRwlock lock;
-  int8_t         inTxn;
-  STsdbFSState  *cState;
-  STsdbFSState  *nState;
+  STsdb        *pTsdb;
+  STsdbFSState *cState;
+  STsdbFSState *nState;
+
+  // new
+  SDelFile *pDelFile;
+  SArray    aDFileSetP;  // SArray<SDFileSet *>
 };
 
 struct SDelFWriter {
@@ -541,6 +562,27 @@ struct SDelFWriter {
   TdFilePtr pWriteH;
 };
 
+struct SDataFWriter {
+  STsdb    *pTsdb;
+  SDFileSet wSet;
+
+  TdFilePtr pHeadFD;
+  TdFilePtr pDataFD;
+  TdFilePtr pLastFD;
+  TdFilePtr pSmaFD;
+
+  SHeadFile fHead;
+  SDataFile fData;
+  SLastFile fLast;
+  SSmaFile  fSma;
+};
+
+struct STsdbReadSnap {
+  SMemTable *pMem;
+  SMemTable *pIMem;
+  STsdbFS    fs;
+};
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/source/dnode/vnode/src/tsdb/tsdbCommit.c b/source/dnode/vnode/src/tsdb/tsdbCommit.c
index 13f310ae27..3c496918e8 100644
--- a/source/dnode/vnode/src/tsdb/tsdbCommit.c
+++ b/source/dnode/vnode/src/tsdb/tsdbCommit.c
@@ -273,7 +273,6 @@ static int32_t tsdbCommitFileDataStart(SCommitter *pCommitter) {
   int32_t    code = 0;
   STsdb     *pTsdb = pCommitter->pTsdb;
   SDFileSet *pRSet = NULL;
-  SDFileSet  wSet;
 
   // memory
   pCommitter->nextKey = TSKEY_MAX;
@@ -292,23 +291,29 @@ static int32_t tsdbCommitFileDataStart(SCommitter *pCommitter) {
   }
 
   // new
+  SHeadFile fHead;
+  SDataFile fData;
+  SLastFile fLast;
+  SSmaFile  fSma;
+  SDFileSet wSet = {.pHeadF = &fHead, .pDataF = &fData, .pLastF = &fLast, .pSmaF = &fSma};
+
   taosArrayClear(pCommitter->aBlockIdxN);
   tMapDataReset(&pCommitter->nBlockMap);
   tBlockDataReset(&pCommitter->nBlockData);
   if (pRSet) {
-    wSet = (SDFileSet){.diskId = pRSet->diskId,
-                       .fid = pCommitter->commitFid,
-                       .fHead = {.commitID = pCommitter->commitID, .offset = 0, .size = 0},
-                       .fData = pRSet->fData,
-                       .fLast = {.commitID = pCommitter->commitID, .size = 0},
-                       .fSma = pRSet->fSma};
+    wSet.diskId = pRSet->diskId;
+    wSet.fid = pCommitter->commitFid;
+    fHead = (SHeadFile){.commitID = pCommitter->commitID, .offset = 0, .size = 0};
+    fData = *pRSet->pDataF;
+    fLast = (SLastFile){.commitID = pCommitter->commitID, .size = 0};
+    fSma = *pRSet->pSmaF;
   } else {
-    wSet = (SDFileSet){.diskId = (SDiskID){.level = 0, .id = 0},
-                       .fid = pCommitter->commitFid,
-                       .fHead = {.commitID = pCommitter->commitID, .offset = 0, .size = 0},
-                       .fData = {.commitID = pCommitter->commitID, .size = 0},
-                       .fLast = {.commitID = pCommitter->commitID, .size = 0},
-                       .fSma = {.commitID = pCommitter->commitID, .size = 0}};
+    wSet.diskId = (SDiskID){.level = 0, .id = 0};
+    wSet.fid = pCommitter->commitFid;
+    fHead = (SHeadFile){.commitID = pCommitter->commitID, .offset = 0, .size = 0};
+    fData = (SDataFile){.commitID = pCommitter->commitID, .size = 0};
+    fLast = (SLastFile){.commitID = pCommitter->commitID, .size = 0};
+    fSma = (SSmaFile){.commitID = pCommitter->commitID, .size = 0};
   }
   code = tsdbDataFWriterOpen(&pCommitter->pWriter, pTsdb, &wSet);
   if (code) goto _err;
@@ -855,7 +860,7 @@ static int32_t tsdbCommitFileDataEnd(SCommitter *pCommitter) {
   if (code) goto _err;
 
   // upsert SDFileSet
-  code = tsdbFSStateUpsertDFileSet(pCommitter->pTsdb->pFS->nState, tsdbDataFWriterGetWSet(pCommitter->pWriter));
+  code = tsdbFSStateUpsertDFileSet(pCommitter->pTsdb->pFS->nState, &pCommitter->pWriter->wSet);
   if (code) goto _err;
 
   // close and sync
diff --git a/source/dnode/vnode/src/tsdb/tsdbFS.c b/source/dnode/vnode/src/tsdb/tsdbFS.c
index 3bc79621e1..f5e6e9744e 100644
--- a/source/dnode/vnode/src/tsdb/tsdbFS.c
+++ b/source/dnode/vnode/src/tsdb/tsdbFS.c
@@ -174,62 +174,64 @@ static int32_t tsdbApplyDFileSetChange(STsdbFS *pFS, SDFileSet *pFrom, SDFileSet
   char    fname[TSDB_FILENAME_LEN];
 
   if (pFrom && pTo) {
+    bool isSameDisk = (pFrom->diskId.level == pTo->diskId.level) && (pFrom->diskId.id == pTo->diskId.id);
+
     // head
-    if (tsdbFileIsSame(pFrom, pTo, TSDB_HEAD_FILE)) {
-      ASSERT(pFrom->fHead.size == pTo->fHead.size);
-      ASSERT(pFrom->fHead.offset == pTo->fHead.offset);
+    if (isSameDisk && pFrom->pHeadF->commitID == pTo->pHeadF->commitID) {
+      ASSERT(pFrom->pHeadF->size == pTo->pHeadF->size);
+      ASSERT(pFrom->pHeadF->offset == pTo->pHeadF->offset);
     } else {
-      tsdbDataFileName(pFS->pTsdb, pFrom, TSDB_HEAD_FILE, fname);
+      tsdbHeadFileName(pFS->pTsdb, pFrom->diskId, pFrom->fid, pFrom->pHeadF, fname);
       taosRemoveFile(fname);
     }
 
     // data
-    if (tsdbFileIsSame(pFrom, pTo, TSDB_DATA_FILE)) {
-      if (pFrom->fData.size > pTo->fData.size) {
+    if (isSameDisk && pFrom->pDataF->commitID == pTo->pDataF->commitID) {
+      if (pFrom->pDataF->size > pTo->pDataF->size) {
         code = tsdbDFileRollback(pFS->pTsdb, pTo, TSDB_DATA_FILE);
         if (code) goto _err;
       }
     } else {
-      tsdbDataFileName(pFS->pTsdb, pFrom, TSDB_DATA_FILE, fname);
+      tsdbDataFileName(pFS->pTsdb, pFrom->diskId, pFrom->fid, pFrom->pDataF, fname);
       taosRemoveFile(fname);
     }
 
     // last
-    if (tsdbFileIsSame(pFrom, pTo, TSDB_LAST_FILE)) {
-      if (pFrom->fLast.size > pTo->fLast.size) {
+    if (isSameDisk && pFrom->pLastF->commitID == pTo->pLastF->commitID) {
+      if (pFrom->pLastF->size > pTo->pLastF->size) {
         code = tsdbDFileRollback(pFS->pTsdb, pTo, TSDB_LAST_FILE);
         if (code) goto _err;
       }
     } else {
-      tsdbDataFileName(pFS->pTsdb, pFrom, TSDB_LAST_FILE, fname);
+      tsdbLastFileName(pFS->pTsdb, pFrom->diskId, pFrom->fid, pFrom->pLastF, fname);
       taosRemoveFile(fname);
     }
 
     // sma
-    if (tsdbFileIsSame(pFrom, pTo, TSDB_SMA_FILE)) {
-      if (pFrom->fSma.size > pTo->fSma.size) {
+    if (isSameDisk && pFrom->pSmaF->commitID == pTo->pSmaF->commitID) {
+      if (pFrom->pSmaF->size > pTo->pSmaF->size) {
         code = tsdbDFileRollback(pFS->pTsdb, pTo, TSDB_SMA_FILE);
         if (code) goto _err;
       }
     } else {
-      tsdbDataFileName(pFS->pTsdb, pFrom, TSDB_SMA_FILE, fname);
+      tsdbSmaFileName(pFS->pTsdb, pFrom->diskId, pFrom->fid, pFrom->pSmaF, fname);
       taosRemoveFile(fname);
     }
   } else if (pFrom) {
     // head
-    tsdbDataFileName(pFS->pTsdb, pFrom, TSDB_HEAD_FILE, fname);
+    tsdbHeadFileName(pFS->pTsdb, pFrom->diskId, pFrom->fid, pFrom->pHeadF, fname);
     taosRemoveFile(fname);
 
     // data
-    tsdbDataFileName(pFS->pTsdb, pFrom, TSDB_DATA_FILE, fname);
+    tsdbDataFileName(pFS->pTsdb, pFrom->diskId, pFrom->fid, pFrom->pDataF, fname);
     taosRemoveFile(fname);
 
     // last
-    tsdbDataFileName(pFS->pTsdb, pFrom, TSDB_LAST_FILE, fname);
+    tsdbLastFileName(pFS->pTsdb, pFrom->diskId, pFrom->fid, pFrom->pLastF, fname);
     taosRemoveFile(fname);
 
     // fsm
-    tsdbDataFileName(pFS->pTsdb, pFrom, TSDB_SMA_FILE, fname);
+    tsdbSmaFileName(pFS->pTsdb, pFrom->diskId, pFrom->fid, pFrom->pSmaF, fname);
     taosRemoveFile(fname);
   }
 
@@ -341,7 +343,6 @@ static void tsdbFSDestroy(STsdbFS *pFS) {
       taosMemoryFree(pFS->cState);
     }
 
-    taosThreadRwlockDestroy(&pFS->lock);
     taosMemoryFree(pFS);
   }
   // TODO
@@ -358,15 +359,6 @@ static int32_t tsdbFSCreate(STsdb *pTsdb, STsdbFS **ppFS) {
   }
   pFS->pTsdb = pTsdb;
 
-  code = taosThreadRwlockInit(&pFS->lock, NULL);
-  if (code) {
-    taosMemoryFree(pFS);
-    code = TAOS_SYSTEM_ERROR(code);
-    goto _err;
-  }
-
-  pFS->inTxn = 0;
-
   pFS->cState = (STsdbFSState *)taosMemoryCalloc(1, sizeof(STsdbFSState));
   if (pFS->cState == NULL) {
     code = TSDB_CODE_OUT_OF_MEMORY;
@@ -431,7 +423,7 @@ static int32_t tsdbScanAndTryFixFS(STsdbFS *pFS, int8_t deepScan) {
     SDFileSet *pDFileSet = (SDFileSet *)taosArrayGet(pFS->cState->aDFileSet, iSet);
 
     // head =========
-    tsdbDataFileName(pTsdb, pDFileSet, TSDB_HEAD_FILE, fname);
+    tsdbHeadFileName(pTsdb, pDFileSet->diskId, pDFileSet->fid, pDFileSet->pHeadF, fname);
     if (taosStatFile(fname, &size, NULL)) {
       code = TAOS_SYSTEM_ERROR(errno);
       goto _err;
@@ -442,16 +434,16 @@ static int32_t tsdbScanAndTryFixFS(STsdbFS *pFS, int8_t deepScan) {
     }
 
     // data =========
-    tsdbDataFileName(pTsdb, pDFileSet, TSDB_DATA_FILE, fname);
+    tsdbDataFileName(pTsdb, pDFileSet->diskId, pDFileSet->fid, pDFileSet->pDataF, fname);
     if (taosStatFile(fname, &size, NULL)) {
       code = TAOS_SYSTEM_ERROR(errno);
       goto _err;
     }
 
-    if (size < pDFileSet->fData.size) {
+    if (size < pDFileSet->pDataF->size) {
       code = TSDB_CODE_FILE_CORRUPTED;
       goto _err;
-    } else if (size > pDFileSet->fData.size) {
+    } else if (size > pDFileSet->pDataF->size) {
       ASSERT(0);
       // need to rollback the file
     }
@@ -461,16 +453,16 @@ static int32_t tsdbScanAndTryFixFS(STsdbFS *pFS, int8_t deepScan) {
     }
 
     // last ===========
-    tsdbDataFileName(pTsdb, pDFileSet, TSDB_LAST_FILE, fname);
+    tsdbLastFileName(pTsdb, pDFileSet->diskId, pDFileSet->fid, pDFileSet->pLastF, fname);
     if (taosStatFile(fname, &size, NULL)) {
       code = TAOS_SYSTEM_ERROR(errno);
       goto _err;
     }
 
-    if (size < pDFileSet->fLast.size) {
+    if (size < pDFileSet->pLastF->size) {
       code = TSDB_CODE_FILE_CORRUPTED;
       goto _err;
-    } else if (size > pDFileSet->fLast.size) {
+    } else if (size > pDFileSet->pLastF->size) {
       ASSERT(0);
       // need to rollback the file
     }
@@ -480,16 +472,16 @@ static int32_t tsdbScanAndTryFixFS(STsdbFS *pFS, int8_t deepScan) {
     }
 
     // sma =============
-    tsdbDataFileName(pTsdb, pDFileSet, TSDB_SMA_FILE, fname);
+    tsdbSmaFileName(pTsdb, pDFileSet->diskId, pDFileSet->fid, pDFileSet->pSmaF, fname);
     if (taosStatFile(fname, &size, NULL)) {
       code = TAOS_SYSTEM_ERROR(errno);
       goto _err;
     }
 
-    if (size < pDFileSet->fSma.size) {
+    if (size < pDFileSet->pSmaF->size) {
       code = TSDB_CODE_FILE_CORRUPTED;
       goto _err;
-    } else if (size > pDFileSet->fSma.size) {
+    } else if (size > pDFileSet->pSmaF->size) {
       ASSERT(0);
       // need to rollback the file
     }
@@ -573,8 +565,6 @@ int32_t tsdbFSClose(STsdbFS *pFS) {
 int32_t tsdbFSBegin(STsdbFS *pFS) {
   int32_t code = 0;
 
-  ASSERT(!pFS->inTxn);
-
   // SDelFile
   pFS->nState->pDelFile = NULL;
   if (pFS->cState->pDelFile) {
@@ -593,7 +583,6 @@ int32_t tsdbFSBegin(STsdbFS *pFS) {
     }
   }
 
-  pFS->inTxn = 1;
   return code;
 
 _err:
@@ -631,8 +620,6 @@ int32_t tsdbFSCommit(STsdbFS *pFS) {
   code = tsdbFSApplyDiskChange(pFS, pFS->nState, pFS->cState);
   if (code) goto _err;
 
-  pFS->inTxn = 0;
-
   return code;
 
 _err:
@@ -646,8 +633,6 @@ int32_t tsdbFSRollback(STsdbFS *pFS) {
   code = tsdbFSApplyDiskChange(pFS, pFS->nState, pFS->cState);
   if (code) goto _err;
 
-  pFS->inTxn = 0;
-
   return code;
 
 _err:
diff --git a/source/dnode/vnode/src/tsdb/tsdbFile.c b/source/dnode/vnode/src/tsdb/tsdbFile.c
index f15ad072e7..4a41e9fb41 100644
--- a/source/dnode/vnode/src/tsdb/tsdbFile.c
+++ b/source/dnode/vnode/src/tsdb/tsdbFile.c
@@ -15,7 +15,7 @@
 
 #include "tsdb.h"
 
-static int32_t tPutHeadFile(uint8_t *p, SHeadFile *pHeadFile) {
+int32_t tPutHeadFile(uint8_t *p, SHeadFile *pHeadFile) {
   int32_t n = 0;
 
   n += tPutI64v(p ? p + n : p, pHeadFile->commitID);
@@ -35,7 +35,7 @@ static int32_t tGetHeadFile(uint8_t *p, SHeadFile *pHeadFile) {
   return n;
 }
 
-static int32_t tPutDataFile(uint8_t *p, SDataFile *pDataFile) {
+int32_t tPutDataFile(uint8_t *p, SDataFile *pDataFile) {
   int32_t n = 0;
 
   n += tPutI64v(p ? p + n : p, pDataFile->commitID);
@@ -53,7 +53,7 @@ static int32_t tGetDataFile(uint8_t *p, SDataFile *pDataFile) {
   return n;
 }
 
-static int32_t tPutLastFile(uint8_t *p, SLastFile *pLastFile) {
+int32_t tPutLastFile(uint8_t *p, SLastFile *pLastFile) {
   int32_t n = 0;
 
   n += tPutI64v(p ? p + n : p, pLastFile->commitID);
@@ -71,7 +71,7 @@ static int32_t tGetLastFile(uint8_t *p, SLastFile *pLastFile) {
   return n;
 }
 
-static int32_t tPutSmaFile(uint8_t *p, SSmaFile *pSmaFile) {
+int32_t tPutSmaFile(uint8_t *p, SSmaFile *pSmaFile) {
   int32_t n = 0;
 
   n += tPutI64v(p ? p + n : p, pSmaFile->commitID);
@@ -90,90 +90,63 @@ static int32_t tGetSmaFile(uint8_t *p, SSmaFile *pSmaFile) {
 }
 
 // EXPOSED APIS ==================================================
-void tsdbDataFileName(STsdb *pTsdb, SDFileSet *pDFileSet, EDataFileT ftype, char fname[]) {
-  STfs *pTfs = pTsdb->pVnode->pTfs;
-
-  switch (ftype) {
-    case TSDB_HEAD_FILE:
-      snprintf(fname, TSDB_FILENAME_LEN - 1, "%s%s%s%sv%df%dver%" PRId64 "%s", tfsGetDiskPath(pTfs, pDFileSet->diskId),
-               TD_DIRSEP, pTsdb->path, TD_DIRSEP, TD_VID(pTsdb->pVnode), pDFileSet->fid, pDFileSet->fHead.commitID,
-               ".head");
-      break;
-    case TSDB_DATA_FILE:
-      snprintf(fname, TSDB_FILENAME_LEN - 1, "%s%s%s%sv%df%dver%" PRId64 "%s", tfsGetDiskPath(pTfs, pDFileSet->diskId),
-               TD_DIRSEP, pTsdb->path, TD_DIRSEP, TD_VID(pTsdb->pVnode), pDFileSet->fid, pDFileSet->fData.commitID,
-               ".data");
-      break;
-    case TSDB_LAST_FILE:
-      snprintf(fname, TSDB_FILENAME_LEN - 1, "%s%s%s%sv%df%dver%" PRId64 "%s", tfsGetDiskPath(pTfs, pDFileSet->diskId),
-               TD_DIRSEP, pTsdb->path, TD_DIRSEP, TD_VID(pTsdb->pVnode), pDFileSet->fid, pDFileSet->fLast.commitID,
-               ".last");
-      break;
-    case TSDB_SMA_FILE:
-      snprintf(fname, TSDB_FILENAME_LEN - 1, "%s%s%s%sv%df%dver%" PRId64 "%s", tfsGetDiskPath(pTfs, pDFileSet->diskId),
-               TD_DIRSEP, pTsdb->path, TD_DIRSEP, TD_VID(pTsdb->pVnode), pDFileSet->fid, pDFileSet->fSma.commitID,
-               ".sma");
-      break;
-    default:
-      ASSERT(0);
-      break;
-  }
+void tsdbHeadFileName(STsdb *pTsdb, SDiskID did, int32_t fid, SHeadFile *pHeadF, char fname[]) {
+  snprintf(fname, TSDB_FILENAME_LEN - 1, "%s%s%s%sv%df%dver%" PRId64 "%s", tfsGetDiskPath(pTsdb->pVnode->pTfs, did),
+           TD_DIRSEP, pTsdb->path, TD_DIRSEP, TD_VID(pTsdb->pVnode), fid, pHeadF->commitID, ".head");
 }
 
-bool tsdbFileIsSame(SDFileSet *pDFileSet1, SDFileSet *pDFileSet2, EDataFileT ftype) {
-  if (pDFileSet1->diskId.level != pDFileSet2->diskId.level || pDFileSet1->diskId.id != pDFileSet2->diskId.id) {
-    return false;
-  }
+void tsdbDataFileName(STsdb *pTsdb, SDiskID did, int32_t fid, SDataFile *pDataF, char fname[]) {
+  snprintf(fname, TSDB_FILENAME_LEN - 1, "%s%s%s%sv%df%dver%" PRId64 "%s", tfsGetDiskPath(pTsdb->pVnode->pTfs, did),
+           TD_DIRSEP, pTsdb->path, TD_DIRSEP, TD_VID(pTsdb->pVnode), fid, pDataF->commitID, ".data");
+}
 
-  switch (ftype) {
-    case TSDB_HEAD_FILE:
-      return pDFileSet1->fHead.commitID == pDFileSet2->fHead.commitID;
-    case TSDB_DATA_FILE:
-      return pDFileSet1->fData.commitID == pDFileSet2->fData.commitID;
-    case TSDB_LAST_FILE:
-      return pDFileSet1->fLast.commitID == pDFileSet2->fLast.commitID;
-    case TSDB_SMA_FILE:
-      return pDFileSet1->fSma.commitID == pDFileSet2->fSma.commitID;
-    default:
-      ASSERT(0);
-      break;
-  }
+void tsdbLastFileName(STsdb *pTsdb, SDiskID did, int32_t fid, SLastFile *pLastF, char fname[]) {
+  snprintf(fname, TSDB_FILENAME_LEN - 1, "%s%s%s%sv%df%dver%" PRId64 "%s", tfsGetDiskPath(pTsdb->pVnode->pTfs, did),
+           TD_DIRSEP, pTsdb->path, TD_DIRSEP, TD_VID(pTsdb->pVnode), fid, pLastF->commitID, ".last");
+}
+
+void tsdbSmaFileName(STsdb *pTsdb, SDiskID did, int32_t fid, SSmaFile *pSmaF, char fname[]) {
+  snprintf(fname, TSDB_FILENAME_LEN - 1, "%s%s%s%sv%df%dver%" PRId64 "%s", tfsGetDiskPath(pTsdb->pVnode->pTfs, did),
+           TD_DIRSEP, pTsdb->path, TD_DIRSEP, TD_VID(pTsdb->pVnode), fid, pSmaF->commitID, ".sma");
 }
 
 bool tsdbDelFileIsSame(SDelFile *pDelFile1, SDelFile *pDelFile2) { return pDelFile1->commitID == pDelFile2->commitID; }
 
-int32_t tsdbUpdateDFileHdr(TdFilePtr pFD, SDFileSet *pSet, EDataFileT ftype) {
-  int32_t code = 0;
-  int64_t n;
-  char    hdr[TSDB_FHDR_SIZE];
-
-  memset(hdr, 0, TSDB_FHDR_SIZE);
-  tPutDataFileHdr(hdr, pSet, ftype);
-  taosCalcChecksumAppend(0, hdr, TSDB_FHDR_SIZE);
-
-  n = taosLSeekFile(pFD, 0, SEEK_SET);
-  if (n < 0) {
-    code = TAOS_SYSTEM_ERROR(errno);
-    goto _exit;
-  }
-
-  n = taosWriteFile(pFD, hdr, TSDB_FHDR_SIZE);
-  if (n < 0) {
-    code = TAOS_SYSTEM_ERROR(errno);
-    goto _exit;
-  }
-
-_exit:
-  return code;
-}
-
 int32_t tsdbDFileRollback(STsdb *pTsdb, SDFileSet *pSet, EDataFileT ftype) {
   int32_t   code = 0;
   int64_t   size;
+  int64_t   n;
   TdFilePtr pFD;
   char      fname[TSDB_FILENAME_LEN];
+  char      hdr[TSDB_FHDR_SIZE] = {0};
 
-  tsdbDataFileName(pTsdb, pSet, ftype, fname);
+  // truncate
+  switch (ftype) {
+    case TSDB_HEAD_FILE:
+      size = pSet->pHeadF->size;
+      tsdbHeadFileName(pTsdb, pSet->diskId, pSet->fid, pSet->pHeadF, fname);
+      tPutHeadFile(hdr, pSet->pHeadF);
+      break;
+    case TSDB_DATA_FILE:
+      size = pSet->pDataF->size;
+      tsdbDataFileName(pTsdb, pSet->diskId, pSet->fid, pSet->pDataF, fname);
+      tPutDataFile(hdr, pSet->pDataF);
+      break;
+    case TSDB_LAST_FILE:
+      size = pSet->pLastF->size;
+      tsdbLastFileName(pTsdb, pSet->diskId, pSet->fid, pSet->pLastF, fname);
+      tPutLastFile(hdr, pSet->pLastF);
+      break;
+    case TSDB_SMA_FILE:
+      size = pSet->pSmaF->size;
+      tsdbSmaFileName(pTsdb, pSet->diskId, pSet->fid, pSet->pSmaF, fname);
+      tPutSmaFile(hdr, pSet->pSmaF);
+      break;
+    default:
+      ASSERT(0);
+  }
+
+  taosCalcChecksumAppend(0, hdr, TSDB_FHDR_SIZE);
 
   // open
   pFD = taosOpenFile(fname, TD_FILE_WRITE);
@@ -182,31 +155,24 @@ int32_t tsdbDFileRollback(STsdb *pTsdb, SDFileSet *pSet, EDataFileT ftype) {
     goto _err;
   }
 
-  // truncate
-  switch (ftype) {
-    case TSDB_HEAD_FILE:
-      size = pSet->fHead.size;
-      break;
-    case TSDB_DATA_FILE:
-      size = pSet->fData.size;
-      break;
-    case TSDB_LAST_FILE:
-      size = pSet->fLast.size;
-      break;
-    case TSDB_SMA_FILE:
-      size = pSet->fSma.size;
-      break;
-    default:
-      ASSERT(0);
-  }
+  // ftruncate
   if (taosFtruncateFile(pFD, size) < 0) {
     code = TAOS_SYSTEM_ERROR(errno);
     goto _err;
   }
 
   // update header
-  code = tsdbUpdateDFileHdr(pFD, pSet, ftype);
-  if (code) goto _err;
+  n = taosLSeekFile(pFD, 0, SEEK_SET);
+  if (n < 0) {
+    code = TAOS_SYSTEM_ERROR(errno);
+    goto _err;
+  }
+
+  n = taosWriteFile(pFD, hdr, TSDB_FHDR_SIZE);
+  if (n < 0) {
+    code = TAOS_SYSTEM_ERROR(errno);
+    goto _err;
+  }
 
   // sync
   if (taosFsyncFile(pFD) < 0) {
@@ -223,39 +189,16 @@ _err:
   return code;
 }
 
-int32_t tPutDataFileHdr(uint8_t *p, SDFileSet *pSet, EDataFileT ftype) {
-  int32_t n = 0;
-
-  switch (ftype) {
-    case TSDB_HEAD_FILE:
-      n += tPutHeadFile(p ? p + n : p, &pSet->fHead);
-      break;
-    case TSDB_DATA_FILE:
-      n += tPutDataFile(p ? p + n : p, &pSet->fData);
-      break;
-    case TSDB_LAST_FILE:
-      n += tPutLastFile(p ? p + n : p, &pSet->fLast);
-      break;
-    case TSDB_SMA_FILE:
-      n += tPutSmaFile(p ? p + n : p, &pSet->fSma);
-      break;
-    default:
-      ASSERT(0);
-  }
-
-  return n;
-}
-
 int32_t tPutDFileSet(uint8_t *p, SDFileSet *pSet) {
   int32_t n = 0;
 
   n += tPutI32v(p ? p + n : p, pSet->diskId.level);
   n += tPutI32v(p ? p + n : p, pSet->diskId.id);
   n += tPutI32v(p ? p + n : p, pSet->fid);
-  n += tPutHeadFile(p ? p + n : p, &pSet->fHead);
-  n += tPutDataFile(p ? p + n : p, &pSet->fData);
-  n += tPutLastFile(p ? p + n : p, &pSet->fLast);
-  n += tPutSmaFile(p ? p + n : p, &pSet->fSma);
+  n += tPutHeadFile(p ? p + n : p, pSet->pHeadF);
+  n += tPutDataFile(p ? p + n : p, pSet->pDataF);
+  n += tPutLastFile(p ? p + n : p, pSet->pLastF);
+  n += tPutSmaFile(p ? p + n : p, pSet->pSmaF);
 
   return n;
 }
@@ -266,10 +209,10 @@ int32_t tGetDFileSet(uint8_t *p, SDFileSet *pSet) {
   n += tGetI32v(p + n, &pSet->diskId.level);
   n += tGetI32v(p + n, &pSet->diskId.id);
   n += tGetI32v(p + n, &pSet->fid);
-  n += tGetHeadFile(p + n, &pSet->fHead);
-  n += tGetDataFile(p + n, &pSet->fData);
-  n += tGetLastFile(p + n, &pSet->fLast);
-  n += tGetSmaFile(p + n, &pSet->fSma);
+  n += tGetHeadFile(p + n, pSet->pHeadF);
+  n += tGetDataFile(p + n, pSet->pDataF);
+  n += tGetLastFile(p + n, pSet->pLastF);
+  n += tGetSmaFile(p + n, pSet->pSmaF);
 
   return n;
 }
diff --git a/source/dnode/vnode/src/tsdb/tsdbMemTable.c b/source/dnode/vnode/src/tsdb/tsdbMemTable.c
index ee8a23e76e..80ba5f0363 100644
--- a/source/dnode/vnode/src/tsdb/tsdbMemTable.c
+++ b/source/dnode/vnode/src/tsdb/tsdbMemTable.c
@@ -607,6 +607,7 @@ void tsdbUnrefMemTable(SMemTable *pMemTable) {
 }
 
 int32_t tsdbTakeMemSnapshot(STsdb *pTsdb, SMemTable **ppMem, SMemTable **ppIMem) {
+  ASSERT(0);
   int32_t code = 0;
 
   // lock
@@ -640,6 +641,7 @@ _exit:
 }
 
 void tsdbUntakeMemSnapshot(STsdb *pTsdb, SMemTable *pMem, SMemTable *pIMem) {
+  ASSERT(0);
   if (pMem) {
     tsdbUnrefMemTable(pMem);
   }
diff --git a/source/dnode/vnode/src/tsdb/tsdbRead.c b/source/dnode/vnode/src/tsdb/tsdbRead.c
index 5dc1915bff..3375dd69ba 100644
--- a/source/dnode/vnode/src/tsdb/tsdbRead.c
+++ b/source/dnode/vnode/src/tsdb/tsdbRead.c
@@ -3244,3 +3244,59 @@ int32_t tsdbGetTableSchema(SVnode* pVnode, int64_t uid, STSchema** pSchema, int6
 
   return TSDB_CODE_SUCCESS;
 }
+
+int32_t tsdbTakeReadSnap(STsdb* pTsdb, STsdbReadSnap** ppSnap) {
+  int32_t code = 0;
+
+  // alloc
+  *ppSnap = (STsdbReadSnap*)taosMemoryCalloc(1, sizeof(STsdbReadSnap));
+  if (*ppSnap == NULL) {
+    code = TSDB_CODE_OUT_OF_MEMORY;
+    goto _exit;
+  }
+
+  // lock
+  code = taosThreadRwlockRdlock(&pTsdb->rwLock);
+  if (code) {
+    code = TAOS_SYSTEM_ERROR(code);
+    goto _exit;
+  }
+
+  // take snapshot
+  (*ppSnap)->pMem = pTsdb->mem;
+  (*ppSnap)->pIMem = pTsdb->imem;
+
+  if ((*ppSnap)->pMem) {
+    tsdbRefMemTable((*ppSnap)->pMem);
+  }
+
+  if ((*ppSnap)->pIMem) {
+    tsdbRefMemTable((*ppSnap)->pIMem);
+  }
+
+  // fs (todo)
+
+  // unlock
+  code = taosThreadRwlockUnlock(&pTsdb->rwLock);
+  if (code) {
+    code = TAOS_SYSTEM_ERROR(code);
+    goto _exit;
+  }
+
+_exit:
+  return code;
+}
+
+void tsdbUntakeReadSnap(STsdb* pTsdb, STsdbReadSnap* pSnap) {
+  if (pSnap) {
+    if (pSnap->pMem) {
+      tsdbUnrefMemTable(pSnap->pMem);
+    }
+
+    if (pSnap->pIMem) {
+      tsdbUnrefMemTable(pSnap->pIMem);
+    }
+
+    // fs (todo)
+  }
+}
diff --git a/source/dnode/vnode/src/tsdb/tsdbReaderWriter.c b/source/dnode/vnode/src/tsdb/tsdbReaderWriter.c
index 5e8157864f..7365ac23b8 100644
--- a/source/dnode/vnode/src/tsdb/tsdbReaderWriter.c
+++ b/source/dnode/vnode/src/tsdb/tsdbReaderWriter.c
@@ -459,7 +459,7 @@ int32_t tsdbDataFReaderOpen(SDataFReader **ppReader, STsdb *pTsdb, SDFileSet *pS
 
   // open impl
   // head
-  tsdbDataFileName(pTsdb, pSet, TSDB_HEAD_FILE, fname);
+  tsdbHeadFileName(pTsdb, pSet->diskId, pSet->fid, pSet->pHeadF, fname);
   pReader->pHeadFD = taosOpenFile(fname, TD_FILE_READ);
   if (pReader->pHeadFD == NULL) {
     code = TAOS_SYSTEM_ERROR(errno);
@@ -467,7 +467,7 @@ int32_t tsdbDataFReaderOpen(SDataFReader **ppReader, STsdb *pTsdb, SDFileSet *pS
   }
 
   // data
-  tsdbDataFileName(pTsdb, pSet, TSDB_DATA_FILE, fname);
+  tsdbDataFileName(pTsdb, pSet->diskId, pSet->fid, pSet->pDataF, fname);
   pReader->pDataFD = taosOpenFile(fname, TD_FILE_READ);
   if (pReader->pDataFD == NULL) {
     code = TAOS_SYSTEM_ERROR(errno);
@@ -475,7 +475,7 @@ int32_t tsdbDataFReaderOpen(SDataFReader **ppReader, STsdb *pTsdb, SDFileSet *pS
   }
 
   // last
-  tsdbDataFileName(pTsdb, pSet, TSDB_LAST_FILE, fname);
+  tsdbLastFileName(pTsdb, pSet->diskId, pSet->fid, pSet->pLastF, fname);
   pReader->pLastFD = taosOpenFile(fname, TD_FILE_READ);
   if (pReader->pLastFD == NULL) {
     code = TAOS_SYSTEM_ERROR(errno);
@@ -483,7 +483,7 @@ int32_t tsdbDataFReaderOpen(SDataFReader **ppReader, STsdb *pTsdb, SDFileSet *pS
   }
 
   // sma
-  tsdbDataFileName(pTsdb, pSet, TSDB_SMA_FILE, fname);
+  tsdbSmaFileName(pTsdb, pSet->diskId, pSet->fid, pSet->pSmaF, fname);
   pReader->pSmaFD = taosOpenFile(fname, TD_FILE_READ);
   if (pReader->pSmaFD == NULL) {
     code = TAOS_SYSTEM_ERROR(errno);
@@ -536,8 +536,8 @@ _err:
 
 int32_t tsdbReadBlockIdx(SDataFReader *pReader, SArray *aBlockIdx, uint8_t **ppBuf) {
   int32_t   code = 0;
-  int64_t   offset = pReader->pSet->fHead.offset;
-  int64_t   size = pReader->pSet->fHead.size - offset;
+  int64_t   offset = pReader->pSet->pHeadF->offset;
+  int64_t   size = pReader->pSet->pHeadF->size - offset;
   uint8_t  *pBuf = NULL;
   int64_t   n;
   uint32_t  delimiter;
@@ -1211,17 +1211,6 @@ _err:
 }
 
 // SDataFWriter ====================================================
-struct SDataFWriter {
-  STsdb    *pTsdb;
-  SDFileSet wSet;
-  TdFilePtr pHeadFD;
-  TdFilePtr pDataFD;
-  TdFilePtr pLastFD;
-  TdFilePtr pSmaFD;
-};
-
-SDFileSet *tsdbDataFWriterGetWSet(SDataFWriter *pWriter) { return &pWriter->wSet; }
-
 int32_t tsdbDataFWriterOpen(SDataFWriter **ppWriter, STsdb *pTsdb, SDFileSet *pSet) {
   int32_t       code = 0;
   int32_t       flag;
@@ -1237,12 +1226,20 @@ int32_t tsdbDataFWriterOpen(SDataFWriter **ppWriter, STsdb *pTsdb, SDFileSet *pS
     goto _err;
   }
   pWriter->pTsdb = pTsdb;
-  pWriter->wSet = *pSet;
-  pSet = &pWriter->wSet;
+  pWriter->wSet = (SDFileSet){.diskId = pSet->diskId,
+                              .fid = pSet->fid,
+                              .pHeadF = &pWriter->fHead,
+                              .pDataF = &pWriter->fData,
+                              .pLastF = &pWriter->fLast,
+                              .pSmaF = &pWriter->fSma};
+  pWriter->fHead = *pSet->pHeadF;
+  pWriter->fData = *pSet->pDataF;
+  pWriter->fLast = *pSet->pLastF;
+  pWriter->fSma = *pSet->pSmaF;
 
   // head
   flag = TD_FILE_WRITE | TD_FILE_CREATE | TD_FILE_TRUNC;
-  tsdbDataFileName(pTsdb, pSet, TSDB_HEAD_FILE, fname);
+  tsdbHeadFileName(pTsdb, pWriter->wSet.diskId, pWriter->wSet.fid, &pWriter->fHead, fname);
   pWriter->pHeadFD = taosOpenFile(fname, flag);
   if (pWriter->pHeadFD == NULL) {
     code = TAOS_SYSTEM_ERROR(errno);
@@ -1257,28 +1254,28 @@ int32_t tsdbDataFWriterOpen(SDataFWriter **ppWriter, STsdb *pTsdb, SDFileSet *pS
 
   ASSERT(n == TSDB_FHDR_SIZE);
 
-  pSet->fHead.size += TSDB_FHDR_SIZE;
+  pWriter->fHead.size += TSDB_FHDR_SIZE;
 
   // data
-  if (pSet->fData.size == 0) {
+  if (pWriter->fData.size == 0) {
     flag = TD_FILE_WRITE | TD_FILE_CREATE | TD_FILE_TRUNC;
   } else {
     flag = TD_FILE_WRITE;
   }
-  tsdbDataFileName(pTsdb, pSet, TSDB_DATA_FILE, fname);
+  tsdbDataFileName(pTsdb, pWriter->wSet.diskId, pWriter->wSet.fid, &pWriter->fData, fname);
   pWriter->pDataFD = taosOpenFile(fname, flag);
   if (pWriter->pDataFD == NULL) {
     code = TAOS_SYSTEM_ERROR(errno);
     goto _err;
   }
-  if (pSet->fData.size == 0) {
+  if (pWriter->fData.size == 0) {
     n = taosWriteFile(pWriter->pDataFD, hdr, TSDB_FHDR_SIZE);
     if (n < 0) {
       code = TAOS_SYSTEM_ERROR(errno);
       goto _err;
     }
 
-    pSet->fData.size += TSDB_FHDR_SIZE;
+    pWriter->fData.size += TSDB_FHDR_SIZE;
   } else {
     n = taosLSeekFile(pWriter->pDataFD, 0, SEEK_END);
     if (n < 0) {
@@ -1286,29 +1283,29 @@ int32_t tsdbDataFWriterOpen(SDataFWriter **ppWriter, STsdb *pTsdb, SDFileSet *pS
       goto _err;
     }
 
-    ASSERT(n == pSet->fData.size);
+    ASSERT(n == pWriter->fData.size);
   }
 
   // last
-  if (pSet->fLast.size == 0) {
+  if (pWriter->fLast.size == 0) {
     flag = TD_FILE_WRITE | TD_FILE_CREATE | TD_FILE_TRUNC;
   } else {
     flag = TD_FILE_WRITE;
   }
-  tsdbDataFileName(pTsdb, pSet, TSDB_LAST_FILE, fname);
+  tsdbLastFileName(pTsdb, pWriter->wSet.diskId, pWriter->wSet.fid, &pWriter->fLast, fname);
   pWriter->pLastFD = taosOpenFile(fname, flag);
   if (pWriter->pLastFD == NULL) {
     code = TAOS_SYSTEM_ERROR(errno);
     goto _err;
   }
-  if (pSet->fLast.size == 0) {
+  if (pWriter->fLast.size == 0) {
     n = taosWriteFile(pWriter->pLastFD, hdr, TSDB_FHDR_SIZE);
     if (n < 0) {
       code = TAOS_SYSTEM_ERROR(errno);
       goto _err;
     }
 
-    pSet->fLast.size += TSDB_FHDR_SIZE;
+    pWriter->fLast.size += TSDB_FHDR_SIZE;
   } else {
     n = taosLSeekFile(pWriter->pLastFD, 0, SEEK_END);
     if (n < 0) {
@@ -1316,29 +1313,29 @@ int32_t tsdbDataFWriterOpen(SDataFWriter **ppWriter, STsdb *pTsdb, SDFileSet *pS
       goto _err;
     }
 
-    ASSERT(n == pSet->fLast.size);
+    ASSERT(n == pWriter->fLast.size);
   }
 
   // sma
-  if (pSet->fSma.size == 0) {
+  if (pWriter->fSma.size == 0) {
     flag = TD_FILE_WRITE | TD_FILE_CREATE | TD_FILE_TRUNC;
   } else {
     flag = TD_FILE_WRITE;
   }
-  tsdbDataFileName(pTsdb, pSet, TSDB_SMA_FILE, fname);
+  tsdbSmaFileName(pTsdb, pWriter->wSet.diskId, pWriter->wSet.fid, &pWriter->fSma, fname);
   pWriter->pSmaFD = taosOpenFile(fname, flag);
   if (pWriter->pSmaFD == NULL) {
     code = TAOS_SYSTEM_ERROR(errno);
     goto _err;
   }
-  if (pSet->fSma.size == 0) {
+  if (pWriter->fSma.size == 0) {
     n = taosWriteFile(pWriter->pSmaFD, hdr, TSDB_FHDR_SIZE);
     if (n < 0) {
       code = TAOS_SYSTEM_ERROR(errno);
       goto _err;
     }
 
-    pSet->fSma.size += TSDB_FHDR_SIZE;
+    pWriter->fSma.size += TSDB_FHDR_SIZE;
   } else {
     n = taosLSeekFile(pWriter->pSmaFD, 0, SEEK_END);
     if (n < 0) {
@@ -1346,7 +1343,7 @@ int32_t tsdbDataFWriterOpen(SDataFWriter **ppWriter, STsdb *pTsdb, SDFileSet *pS
       goto _err;
     }
 
-    ASSERT(n == pSet->fSma.size);
+    ASSERT(n == pWriter->fSma.size);
   }
 
   *ppWriter = pWriter;
@@ -1418,22 +1415,76 @@ _err:
 
 int32_t tsdbUpdateDFileSetHeader(SDataFWriter *pWriter) {
   int32_t code = 0;
+  int64_t n;
+  char    hdr[TSDB_FHDR_SIZE];
 
   // head ==============
-  code = tsdbUpdateDFileHdr(pWriter->pHeadFD, &pWriter->wSet, TSDB_HEAD_FILE);
-  if (code) goto _err;
+  memset(hdr, 0, TSDB_FHDR_SIZE);
+  tPutHeadFile(hdr, &pWriter->fHead);
+  taosCalcChecksumAppend(0, hdr, TSDB_FHDR_SIZE);
+
+  n = taosLSeekFile(pWriter->pHeadFD, 0, SEEK_SET);
+  if (n < 0) {
+    code = TAOS_SYSTEM_ERROR(errno);
+    goto _err;
+  }
+
+  n = taosWriteFile(pWriter->pHeadFD, hdr, TSDB_FHDR_SIZE);
+  if (n < 0) {
+    code = TAOS_SYSTEM_ERROR(errno);
+    goto _err;
+  }
 
   // data ==============
-  code = tsdbUpdateDFileHdr(pWriter->pHeadFD, &pWriter->wSet, TSDB_DATA_FILE);
-  if (code) goto _err;
+  memset(hdr, 0, TSDB_FHDR_SIZE);
+  tPutDataFile(hdr, &pWriter->fData);
+  taosCalcChecksumAppend(0, hdr, TSDB_FHDR_SIZE);
+
+  n = taosLSeekFile(pWriter->pDataFD, 0, SEEK_SET);
+  if (n < 0) {
+    code = TAOS_SYSTEM_ERROR(errno);
+    goto _err;
+  }
+
+  n = taosWriteFile(pWriter->pDataFD, hdr, TSDB_FHDR_SIZE);
+  if (n < 0) {
+    code = TAOS_SYSTEM_ERROR(errno);
+    goto _err;
+  }
 
   // last ==============
-  code = tsdbUpdateDFileHdr(pWriter->pHeadFD, &pWriter->wSet, TSDB_LAST_FILE);
-  if (code) goto _err;
+  memset(hdr, 0, TSDB_FHDR_SIZE);
+  tPutLastFile(hdr, &pWriter->fLast);
+  taosCalcChecksumAppend(0, hdr, TSDB_FHDR_SIZE);
+
+  n = taosLSeekFile(pWriter->pLastFD, 0, SEEK_SET);
+  if (n < 0) {
+    code = TAOS_SYSTEM_ERROR(errno);
+    goto _err;
+  }
+
+  n = taosWriteFile(pWriter->pLastFD, hdr, TSDB_FHDR_SIZE);
+  if (n < 0) {
+    code = TAOS_SYSTEM_ERROR(errno);
+    goto _err;
+  }
 
   // sma ==============
-  code = tsdbUpdateDFileHdr(pWriter->pHeadFD, &pWriter->wSet, TSDB_SMA_FILE);
-  if (code) goto _err;
+  memset(hdr, 0, TSDB_FHDR_SIZE);
+  tPutSmaFile(hdr, &pWriter->fSma);
+  taosCalcChecksumAppend(0, hdr, TSDB_FHDR_SIZE);
+
+  n = taosLSeekFile(pWriter->pSmaFD, 0, SEEK_SET);
+  if (n < 0) {
+    code = TAOS_SYSTEM_ERROR(errno);
+    goto _err;
+  }
+
+  n = taosWriteFile(pWriter->pSmaFD, hdr, TSDB_FHDR_SIZE);
+  if (n < 0) {
+    code = TAOS_SYSTEM_ERROR(errno);
+    goto _err;
+  }
 
   return code;
 
@@ -1444,7 +1495,7 @@ _err:
 
 int32_t tsdbWriteBlockIdx(SDataFWriter *pWriter, SArray *aBlockIdx, uint8_t **ppBuf) {
   int32_t    code = 0;
-  SHeadFile *pHeadFile = &pWriter->wSet.fHead;
+  SHeadFile *pHeadFile = &pWriter->fHead;
   uint8_t   *pBuf = NULL;
   int64_t    size;
   int64_t    n;
@@ -1494,7 +1545,7 @@ _err:
 
 int32_t tsdbWriteBlock(SDataFWriter *pWriter, SMapData *mBlock, uint8_t **ppBuf, SBlockIdx *pBlockIdx) {
   int32_t       code = 0;
-  SHeadFile    *pHeadFile = &pWriter->wSet.fHead;
+  SHeadFile    *pHeadFile = &pWriter->fHead;
   SBlockDataHdr hdr = {.delimiter = TSDB_FILE_DLMT, .suid = pBlockIdx->suid, .uid = pBlockIdx->uid};
   uint8_t      *pBuf = NULL;
   int64_t       size;
@@ -1831,9 +1882,9 @@ int32_t tsdbWriteBlockData(SDataFWriter *pWriter, SBlockData *pBlockData, uint8_
   pSubBlock->nRow = pBlockData->nRow;
   pSubBlock->cmprAlg = cmprAlg;
   if (pBlock->last) {
-    pSubBlock->offset = pWriter->wSet.fLast.size;
+    pSubBlock->offset = pWriter->fLast.size;
   } else {
-    pSubBlock->offset = pWriter->wSet.fData.size;
+    pSubBlock->offset = pWriter->fData.size;
   }
 
   // ======================= BLOCK DATA =======================
@@ -1881,9 +1932,9 @@ int32_t tsdbWriteBlockData(SDataFWriter *pWriter, SBlockData *pBlockData, uint8_
 
   pSubBlock->szBlock = pSubBlock->szBlockCol + sizeof(TSCKSUM) + nData;
   if (pBlock->last) {
-    pWriter->wSet.fLast.size += pSubBlock->szBlock;
+    pWriter->fLast.size += pSubBlock->szBlock;
   } else {
-    pWriter->wSet.fData.size += pSubBlock->szBlock;
+    pWriter->fData.size += pSubBlock->szBlock;
   }
 
   // ======================= BLOCK SMA =======================
@@ -1896,8 +1947,8 @@ int32_t tsdbWriteBlockData(SDataFWriter *pWriter, SBlockData *pBlockData, uint8_
   if (code) goto _err;
 
   if (pSubBlock->nSma > 0) {
-    pSubBlock->sOffset = pWriter->wSet.fSma.size;
-    pWriter->wSet.fSma.size += (sizeof(SColumnDataAgg) * pSubBlock->nSma + sizeof(TSCKSUM));
+    pSubBlock->sOffset = pWriter->fSma.size;
+    pWriter->fSma.size += (sizeof(SColumnDataAgg) * pSubBlock->nSma + sizeof(TSCKSUM));
   }
 
 _exit:
@@ -1924,8 +1975,8 @@ int32_t tsdbDFileSetCopy(STsdb *pTsdb, SDFileSet *pSetFrom, SDFileSet *pSetTo) {
   char      fNameTo[TSDB_FILENAME_LEN];
 
   // head
-  tsdbDataFileName(pTsdb, pSetFrom, TSDB_HEAD_FILE, fNameFrom);
-  tsdbDataFileName(pTsdb, pSetTo, TSDB_HEAD_FILE, fNameTo);
+  tsdbHeadFileName(pTsdb, pSetFrom->diskId, pSetFrom->fid, pSetFrom->pHeadF, fNameFrom);
+  tsdbHeadFileName(pTsdb, pSetTo->diskId, pSetTo->fid, pSetTo->pHeadF, fNameTo);
 
   pOutFD = taosOpenFile(fNameTo, TD_FILE_WRITE | TD_FILE_CREATE | TD_FILE_TRUNC);
   if (pOutFD == NULL) {
@@ -1939,7 +1990,7 @@ int32_t tsdbDFileSetCopy(STsdb *pTsdb, SDFileSet *pSetFrom, SDFileSet *pSetTo) {
     goto _err;
   }
 
-  n = taosFSendFile(pOutFD, PInFD, 0, pSetFrom->fHead.size);
+  n = taosFSendFile(pOutFD, PInFD, 0, pSetFrom->pHeadF->size);
   if (n < 0) {
     code = TAOS_SYSTEM_ERROR(errno);
     goto _err;
@@ -1948,8 +1999,8 @@ int32_t tsdbDFileSetCopy(STsdb *pTsdb, SDFileSet *pSetFrom, SDFileSet *pSetTo) {
   taosCloseFile(&PInFD);
 
   // data
-  tsdbDataFileName(pTsdb, pSetFrom, TSDB_DATA_FILE, fNameFrom);
-  tsdbDataFileName(pTsdb, pSetTo, TSDB_DATA_FILE, fNameTo);
+  tsdbDataFileName(pTsdb, pSetFrom->diskId, pSetFrom->fid, pSetFrom->pDataF, fNameFrom);
+  tsdbDataFileName(pTsdb, pSetTo->diskId, pSetTo->fid, pSetTo->pDataF, fNameTo);
 
   pOutFD = taosOpenFile(fNameTo, TD_FILE_WRITE | TD_FILE_CREATE | TD_FILE_TRUNC);
   if (pOutFD == NULL) {
@@ -1963,7 +2014,7 @@ int32_t tsdbDFileSetCopy(STsdb *pTsdb, SDFileSet *pSetFrom, SDFileSet *pSetTo) {
     goto _err;
   }
 
-  n = taosFSendFile(pOutFD, PInFD, 0, pSetFrom->fData.size);
+  n = taosFSendFile(pOutFD, PInFD, 0, pSetFrom->pDataF->size);
   if (n < 0) {
     code = TAOS_SYSTEM_ERROR(errno);
     goto _err;
@@ -1972,8 +2023,9 @@ int32_t tsdbDFileSetCopy(STsdb *pTsdb, SDFileSet *pSetFrom, SDFileSet *pSetTo) {
   taosCloseFile(&PInFD);
 
   // last
-  tsdbDataFileName(pTsdb, pSetFrom, TSDB_LAST_FILE, fNameFrom);
-  tsdbDataFileName(pTsdb, pSetTo, TSDB_LAST_FILE, fNameTo);
+  tsdbLastFileName(pTsdb, pSetFrom->diskId, pSetFrom->fid, pSetFrom->pLastF, fNameFrom);
+  tsdbLastFileName(pTsdb, pSetTo->diskId, pSetTo->fid, pSetTo->pLastF, fNameTo);
+
   pOutFD = taosOpenFile(fNameTo, TD_FILE_WRITE | TD_FILE_CREATE | TD_FILE_TRUNC);
   if (pOutFD == NULL) {
     code = TAOS_SYSTEM_ERROR(errno);
@@ -1986,7 +2038,7 @@ int32_t tsdbDFileSetCopy(STsdb *pTsdb, SDFileSet *pSetFrom, SDFileSet *pSetTo) {
     goto _err;
   }
 
-  n = taosFSendFile(pOutFD, PInFD, 0, pSetFrom->fLast.size);
+  n = taosFSendFile(pOutFD, PInFD, 0, pSetFrom->pLastF->size);
   if (n < 0) {
     code = TAOS_SYSTEM_ERROR(errno);
     goto _err;
@@ -1995,8 +2047,8 @@ int32_t tsdbDFileSetCopy(STsdb *pTsdb, SDFileSet *pSetFrom, SDFileSet *pSetTo) {
   taosCloseFile(&PInFD);
 
   // sma
-  tsdbDataFileName(pTsdb, pSetFrom, TSDB_SMA_FILE, fNameFrom);
-  tsdbDataFileName(pTsdb, pSetTo, TSDB_SMA_FILE, fNameTo);
+  tsdbSmaFileName(pTsdb, pSetFrom->diskId, pSetFrom->fid, pSetFrom->pSmaF, fNameFrom);
+  tsdbSmaFileName(pTsdb, pSetTo->diskId, pSetTo->fid, pSetTo->pSmaF, fNameTo);
 
   pOutFD = taosOpenFile(fNameTo, TD_FILE_WRITE | TD_FILE_CREATE | TD_FILE_TRUNC);
   if (pOutFD == NULL) {
@@ -2010,7 +2062,7 @@ int32_t tsdbDFileSetCopy(STsdb *pTsdb, SDFileSet *pSetFrom, SDFileSet *pSetTo) {
     goto _err;
   }
 
-  n = taosFSendFile(pOutFD, PInFD, 0, pSetFrom->fSma.size);
+  n = taosFSendFile(pOutFD, PInFD, 0, pSetFrom->pSmaF->size);
   if (n < 0) {
     code = TAOS_SYSTEM_ERROR(errno);
     goto _err;
diff --git a/source/dnode/vnode/src/tsdb/tsdbSnapshot.c b/source/dnode/vnode/src/tsdb/tsdbSnapshot.c
index fea0254045..dfb01f2ded 100644
--- a/source/dnode/vnode/src/tsdb/tsdbSnapshot.c
+++ b/source/dnode/vnode/src/tsdb/tsdbSnapshot.c
@@ -798,7 +798,7 @@ static int32_t tsdbSnapWriteDataEnd(STsdbSnapWriter* pWriter) {
   code = tsdbWriteBlockIdx(pWriter->pDataFWriter, pWriter->aBlockIdxW, NULL);
   if (code) goto _err;
 
-  code = tsdbFSStateUpsertDFileSet(pTsdb->pFS->nState, tsdbDataFWriterGetWSet(pWriter->pDataFWriter));
+  code = tsdbFSStateUpsertDFileSet(pTsdb->pFS->nState, &pWriter->pDataFWriter->wSet);
   if (code) goto _err;
 
   code = tsdbDataFWriterClose(&pWriter->pDataFWriter, 1);
@@ -863,22 +863,26 @@ static int32_t tsdbSnapWriteData(STsdbSnapWriter* pWriter, uint8_t* pData, uint3
     tBlockDataReset(&pWriter->bDataR);
 
     // write
-    SDFileSet wSet;
+    SHeadFile fHead;
+    SDataFile fData;
+    SLastFile fLast;
+    SSmaFile  fSma;
+    SDFileSet wSet = {.pHeadF = &fHead, .pDataF = &fData, .pLastF = &fLast, .pSmaF = &fSma};
 
     if (pSet) {
-      wSet = (SDFileSet){.diskId = pSet->diskId,
-                         .fid = fid,
-                         .fHead = {.commitID = pWriter->commitID, .offset = 0, .size = 0},
-                         .fData = pSet->fData,
-                         .fLast = {.commitID = pWriter->commitID, .size = 0},
-                         .fSma = pSet->fSma};
+      wSet.diskId = pSet->diskId;
+      wSet.fid = fid;
+      fHead = (SHeadFile){.commitID = pWriter->commitID, .offset = 0, .size = 0};
+      fData = *pSet->pDataF;
+      fLast = (SLastFile){.commitID = pWriter->commitID, .size = 0};
+      fSma = *pSet->pSmaF;
     } else {
-      wSet = (SDFileSet){.diskId = (SDiskID){.level = 0, .id = 0},
-                         .fid = fid,
-                         .fHead = {.commitID = pWriter->commitID, .offset = 0, .size = 0},
-                         .fData = {.commitID = pWriter->commitID, .size = 0},
-                         .fLast = {.commitID = pWriter->commitID, .size = 0},
-                         .fSma = {.commitID = pWriter->commitID, .size = 0}};
+      wSet.diskId = (SDiskID){.level = 0, .id = 0};
+      wSet.fid = fid;
+      fHead = (SHeadFile){.commitID = pWriter->commitID, .offset = 0, .size = 0};
+      fData = (SDataFile){.commitID = pWriter->commitID, .size = 0};
+      fLast = (SLastFile){.commitID = pWriter->commitID, .size = 0};
+      fSma = (SSmaFile){.commitID = pWriter->commitID, .size = 0};
     }
 
     code = tsdbDataFWriterOpen(&pWriter->pDataFWriter, pTsdb, &wSet);