diff --git a/source/dnode/vnode/src/inc/tsdb.h b/source/dnode/vnode/src/inc/tsdb.h
index 6af1a1a79b96d2f1c6a74ff4009f07a7fc2fa6b7..e1bbc3278dabd783ed708485aeacfff9b67db291 100644
--- a/source/dnode/vnode/src/inc/tsdb.h
+++ b/source/dnode/vnode/src/inc/tsdb.h
@@ -188,6 +188,7 @@ 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 tsdbReadAndCheckFile(TdFilePtr pFD, int64_t offset, uint8_t **ppOut, int32_t size);
 // tsdbMemTable ==============================================================================================
 // SMemTable
 int32_t tsdbMemTableCreate(STsdb *pTsdb, SMemTable **ppMemTable);
diff --git a/source/dnode/vnode/src/tsdb/tsdbReaderWriter.c b/source/dnode/vnode/src/tsdb/tsdbReaderWriter.c
index 4f02299c7e3ba194fe6cee747932633b57c9b6d4..94d957eac770eed9fe7f1cb842becef8898d1863 100644
--- a/source/dnode/vnode/src/tsdb/tsdbReaderWriter.c
+++ b/source/dnode/vnode/src/tsdb/tsdbReaderWriter.c
@@ -401,6 +401,7 @@ struct SDataFReader {
 
   uint8_t *pBuf1;
   uint8_t *pBuf2;
+  uint8_t *pBuf3;
 };
 
 int32_t tsdbDataFReaderOpen(SDataFReader **ppReader, STsdb *pTsdb, SDFileSet *pSet) {
@@ -485,6 +486,7 @@ int32_t tsdbDataFReaderClose(SDataFReader **ppReader) {
 
   tFree((*ppReader)->pBuf1);
   tFree((*ppReader)->pBuf2);
+  tFree((*ppReader)->pBuf3);
   taosMemoryFree(*ppReader);
 
 _exit:
@@ -729,94 +731,75 @@ static int32_t tsdbReadBlockDataImpl(SDataFReader *pReader, SBlockInfo *pBlkInfo
                                      int32_t nColId, SBlockData *pBlockData) {
   int32_t code = 0;
 
+  // TODO
   tBlockDataReset(pBlockData);
 
   TdFilePtr pFD = fromLast ? pReader->pLastFD : pReader->pDataFD;
 
-  // seek
-  int64_t n = taosLSeekFile(pFD, pBlkInfo->offset, SEEK_SET);
-  if (n < 0) {
-    code = TAOS_SYSTEM_ERROR(errno);
-    goto _err;
-  }
-
-  // read
-  code = tRealloc(&pReader->pBuf1, pBlkInfo->szBlock);
+  // uid + version + tskey
+  code = tsdbReadAndCheckFile(pFD, pBlkInfo->offset, &pReader->pBuf1, pBlkInfo->szKey);
   if (code) goto _err;
-
-  n = taosReadFile(pFD, pReader->pBuf1, pBlkInfo->szBlock);
-  if (n < 0) {
-    code = TAOS_SYSTEM_ERROR(errno);
-    goto _err;
-  } else if (n < pBlkInfo->szBlock) {
-    code = TSDB_CODE_FILE_CORRUPTED;
-    goto _err;
-  }
-
-  uint8_t *p = pReader->pBuf1;
-  // check & decode
   SDiskDataHdr hdr;
-  if (!taosCheckChecksumWhole(p, pBlkInfo->szKey)) {
-    code = TSDB_CODE_FILE_CORRUPTED;
-    goto _err;
-  }
-  p += tGetDiskDataHdr(p, &hdr);
+  uint8_t     *p = pReader->pBuf1 + tGetDiskDataHdr(pReader->pBuf1, &hdr);
+
+  ASSERT(hdr.delimiter == TSDB_FILE_DLMT);
+  ASSERT(hdr.suid || hdr.uid);
 
-  tBlockDataSetSchema(pBlockData, NULL, hdr.suid, hdr.uid);
+  pBlockData->suid = hdr.suid;
+  pBlockData->uid = hdr.uid;
   pBlockData->nRow = hdr.nRow;
 
+  // uid
   if (hdr.uid == 0) {
     ASSERT(hdr.szUid);
     code = tsdbDecmprData(p, hdr.szUid, TSDB_DATA_TYPE_BIGINT, hdr.cmprAlg, (uint8_t **)&pBlockData->aUid,
                           sizeof(int64_t) * hdr.nRow, &pReader->pBuf2);
     if (code) goto _err;
   } else {
-    ASSERT(hdr.szUid == 0);
+    ASSERT(!hdr.szUid);
   }
   p += hdr.szUid;
 
+  // version
   code = tsdbDecmprData(p, hdr.szVer, TSDB_DATA_TYPE_BIGINT, hdr.cmprAlg, (uint8_t **)&pBlockData->aVersion,
                         sizeof(int64_t) * hdr.nRow, &pReader->pBuf2);
   if (code) goto _err;
   p += hdr.szVer;
 
-  code = tsdbDecmprData(p, hdr.szKey, TSDB_DATA_TYPE_BIGINT, hdr.cmprAlg, (uint8_t **)&pBlockData->aTSKEY,
+  // TSKEY
+  code = tsdbDecmprData(p, hdr.szKey, TSDB_DATA_TYPE_TIMESTAMP, hdr.cmprAlg, (uint8_t **)&pBlockData->aTSKEY,
                         sizeof(TSKEY) * hdr.nRow, &pReader->pBuf2);
   if (code) goto _err;
   p += hdr.szKey;
-  p += sizeof(TSCKSUM);
 
-  // SBlockCol
+  ASSERT(p - pReader->pBuf1 == sizeof(TSCKSUM));
+
+  // read and decode columns
   if (hdr.szBlkCol > 0) {
-    if (!taosCheckChecksumWhole(p, hdr.szBlkCol + sizeof(TSCKSUM))) {
-      code = TSDB_CODE_FILE_CORRUPTED;
-      goto _err;
-    }
+    code =
+        tsdbReadAndCheckFile(pFD, pBlkInfo->offset + pBlkInfo->szKey, &pReader->pBuf1, hdr.szBlkCol + sizeof(TSCKSUM));
+    if (code) goto _err;
 
-    int32_t  iColData = 0;
-    uint8_t *pt = p + hdr.szBlkCol + sizeof(TSCKSUM);
-    n = 0;
+    int32_t n = 0;
     while (n < hdr.szBlkCol) {
       SBlockCol blockCol;
 
-      n += tGetBlockCol(p + n, &blockCol);
+      n += tGetBlockCol(pReader->pBuf1 + n, &blockCol);
 
       ASSERT(blockCol.flag && blockCol.flag != HAS_NONE);
 
-      SColData *pColData;
-      code = tBlockDataAddColData(pBlockData, iColData, &pColData);
-      if (code) goto _err;
-      iColData++;
+      // TODO: merge with the column IDs
 
-      tColDataInit(pColData, blockCol.cid, blockCol.type, blockCol.smaOn);
+      SColData *pColData = NULL;  // (todo)
 
       if (blockCol.flag == HAS_NULL) {
-        for (int32_t iRow = 0; iRow < pBlockData->nRow; iRow++) {
-          code = tColDataAppendValue(pColData, &COL_VAL_NULL(blockCol.cid, blockCol.type));
-          if (code) goto _err;
-        }
+        // TODO: make a hdr.nRow COL_VAL_NULL();
       } else {
-        code = tsdbDecmprColData(pt + blockCol.offset, &blockCol, hdr.cmprAlg, hdr.nRow, pColData, &pReader->pBuf2);
+        code = tsdbReadAndCheckFile(
+            pFD, pBlkInfo->offset + pBlkInfo->szKey + hdr.szBlkCol + sizeof(TSCKSUM) + blockCol.offset, &pReader->pBuf2,
+            blockCol.szBitmap + blockCol.szOffset + blockCol.szValue + sizeof(TSCKSUM));
+
+        code = tsdbDecmprColData(pReader->pBuf2, &blockCol, hdr.cmprAlg, hdr.nRow, pColData, &pReader->pBuf3);
         if (code) goto _err;
       }
     }
diff --git a/source/dnode/vnode/src/tsdb/tsdbUtil.c b/source/dnode/vnode/src/tsdb/tsdbUtil.c
index dbb35532e823166ff1bb6727b2924907a30f651f..6a27b10cf1a7f268de07c2501c9830a9814c742c 100644
--- a/source/dnode/vnode/src/tsdb/tsdbUtil.c
+++ b/source/dnode/vnode/src/tsdb/tsdbUtil.c
@@ -1865,6 +1865,40 @@ int32_t tsdbDecmprColData(uint8_t *pIn, SBlockCol *pBlockCol, int8_t cmprAlg, in
   }
   p += pBlockCol->szValue;
 
+_exit:
+  return code;
+}
+
+int32_t tsdbReadAndCheckFile(TdFilePtr pFD, int64_t offset, uint8_t **ppOut, int32_t size) {
+  int32_t code = 0;
+
+  // alloc
+  code = tRealloc(ppOut, size);
+  if (code) goto _exit;
+
+  // seek
+  int64_t n = taosLSeekFile(pFD, offset, SEEK_SET);
+  if (n < 0) {
+    code = TAOS_SYSTEM_ERROR(errno);
+    goto _exit;
+  }
+
+  // read
+  n = taosReadFile(pFD, *ppOut, size);
+  if (n < 0) {
+    code = TAOS_SYSTEM_ERROR(errno);
+    goto _exit;
+  } else if (n < size) {
+    code = TSDB_CODE_FILE_CORRUPTED;
+    goto _exit;
+  }
+
+  // check
+  if (!taosCheckChecksumWhole(*ppOut, size)) {
+    code = TSDB_CODE_FILE_CORRUPTED;
+    goto _exit;
+  }
+
 _exit:
   return code;
 }
\ No newline at end of file