diff --git a/src/tsdb/inc/tsdbMain.h b/src/tsdb/inc/tsdbMain.h
index cb3f7eb22ce29810f2c3440ee0d13245e2593280..50cf80857ea201502c7d18c91f820a218607b087 100644
--- a/src/tsdb/inc/tsdbMain.h
+++ b/src/tsdb/inc/tsdbMain.h
@@ -332,9 +332,11 @@ typedef struct {
   TSKEY       maxKey;
   SBlockIdx*  pBlockIdx;
   int         nBlockIdx;
+  int         cBlockIdx;
   SBlockIdx*  pCurBlockIdx;
   STable*     pTable;
   SBlockInfo* pBlockInfo;
+  SBlockData* pBlockData;
   SDataCols*  pDataCols[2];
   void*       pBuf;
   void*       pCBuf;
@@ -592,6 +594,9 @@ typedef struct {
   void*      pBuffer;
   SList*     pModLog;
 } SCommitHandle;
+
+void tsdbResetFGroupFd(SFileGroup* pFGroup);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/src/tsdb/src/tsdbReadUtil.c b/src/tsdb/src/tsdbReadUtil.c
index 2c6529ab4c7b4d10ac434625a4e9e9d16a45f024..5e58ad48acf1f4149696507165239180f07c9f5c 100644
--- a/src/tsdb/src/tsdbReadUtil.c
+++ b/src/tsdb/src/tsdbReadUtil.c
@@ -21,27 +21,57 @@
 #include "tscompression.h"
 #include "tsdbMain.h"
 
-int tsdbInitReadHandle(SReadHandle *pReadH, STsdbRepo *pRepo) {
+#define TSDB_KEY_COL_OFFSET 0
+
+SReadHandle *tsdbNewReadHandle(STsdbRepo *pRepo) {
+  SReadHandle *pReadH = (SReadHandle *)calloc(1, sizeof(*pReadH));
+  if (pReadH == NULL) {
+    terrno = TSDB_CODE_TDB_OUT_OF_MEMORY;
+    return NULL;
+  }
+
   pReadH->pRepo = pRepo;
-  return 0;
+
+  STsdbMeta *pMeta = pRepo->tsdbMeta;
+  STsdbCfg * pCfg = &(pRepo->config);
+
+  if ((pReadH->pDataCols[0] = tdNewDataCols(pMeta->maxRowBytes, pMeta->maxCols, pCfg->maxRowsPerFileBlock)) == NULL ||
+      (pReadH->pDataCols[1] = tdNewDataCols(pMeta->maxRowBytes, pMeta->maxCols, pCfg->maxRowsPerFileBlock)) == NULL) {
+    terrno = TSDB_CODE_TDB_OUT_OF_MEMORY;
+    tsdbFreeReadHandle(pReadH);
+    return NULL;
+  }
+
+  tsdbResetFGroupFd(&(pReadH->fGroup));
+
+  return pReadH;
 }
 
-void tsdbDestroyReadHandle(SReadHandle *pReadH) {
-  // TODO
+void tsdbFreeReadHandle(SReadHandle *pReadH) {
+  if (pReadH) {
+    taosTZfree(pReadH->pBlockIdx);
+    taosTZfree(pReadH->pBlockInfo);
+    taosTZfree(pReadH->pBlockData);
+    tdFreeDataCols(pReadH->pDataCols[0]);
+    tdFreeDataCols(pReadH->pDataCols[1]);
+    taosTZfree(pReadH->pBuf);
+    taosTZfree(pReadH->pCBuf);
+    free(pReadH);
+  }
 }
 
 int tsdbSetAndOpenFGroup(SReadHandle *pReadH, SFileGroup *pFGroup) {
   STsdbRepo *pRepo = pReadH->pRepo;
+  STsdbCfg * pCfg = &(pRepo->config);
+
   pReadH->fGroup = *pFGroup;
 
-  for (int type = 0; type < TSDB_FILE_TYPE_MAX; type++) {
-    pReadH->fGroup.files[type].fd = -1;
-  }
+  tsdbResetFGroupFd(&(pReadH->fGroup));
 
   for (int type = 0; type < TSDB_FILE_TYPE_MAX; type++) {
-    SFile *pFile = &(pReadH->fGroup.files[type]);
+    SFile *pFile = TSDB_READ_FILE(pReadH, type);
 
-    if (pFile->fname[0] != '\0') {
+    if (pFile->fname[0] != '\0') {  // pFile->fname[0] == '\0' is for commit usage
       pFile->fd = open(pFile->fname, O_RDONLY);
       if (pFile->fd < 0) {
         tsdbError("vgId:%d failed to open file %s since %s", REPO_ID(pRepo), pFile->fname, strerror(errno));
@@ -52,14 +82,16 @@ int tsdbSetAndOpenFGroup(SReadHandle *pReadH, SFileGroup *pFGroup) {
     }
   }
 
+  tsdbGetFidKeyRange(pCfg->daysPerFile, pCfg->precision, pFGroup->fileId, &(pReadH->minKey), &(pReadH->maxKey));
+
   return 0;
 }
 
 void tsdbCloseAndUnsetFile(SReadHandle *pReadH) {
   for (int type = 0; type < TSDB_FILE_TYPE_MAX; type++) {
-    SFile *pFile = &(pReadH->fGroup.files[type]);
+    SFile *pFile = TSDB_READ_FILE(pReadH, type);
 
-    if (pFile->fd > 0) {
+    if (pFile->fd >= 0) {
       (void)close(pFile->fd);
       pFile->fd = -1;
     }
@@ -68,20 +100,22 @@ void tsdbCloseAndUnsetFile(SReadHandle *pReadH) {
 
 int tsdbLoadBlockIdx(SReadHandle *pReadH) {
   STsdbRepo *pRepo = pReadH->pRepo;
-  SFile *    pFile = &(pReadH->fGroup.files[TSDB_FILE_TYPE_HEAD]);
+  SFile *    pFile = TSDB_READ_FILE(pReadH, TSDB_FILE_TYPE_HEAD);
 
   if (pFile->fd < 0 || pFile->info.len == 0) {
     pReadH->nBlockIdx = 0;
+    pReadH->pCurBlockIdx = NULL;
     return 0;
   }
 
   if (tsdbAllocBuf(&(pReadH->pBuf), pFile->info.len) < 0) {
-    terrno = TAOS_SYSTEM_ERROR(errno);
+    terrno = TSDB_CODE_TDB_OUT_OF_MEMORY;
     return -1;
   }
 
   if (lseek(pFile->fd, pFile->info.offset, SEEK_SET) < 0) {
-    tsdbError("vgId:%d failed to lseek file %s since %s", REPO_ID(pRepo), pFile->fname, strerror(errno));
+    tsdbError("vgId:%d failed to lseek file %s to offset %u since %s", REPO_ID(pRepo), pFile->fname, pFile->info.offset,
+              strerror(errno));
     terrno = TAOS_SYSTEM_ERROR(errno);
     return -1;
   }
@@ -94,7 +128,7 @@ int tsdbLoadBlockIdx(SReadHandle *pReadH) {
     return -1;
   }
 
-  if (ret < pFile->info.len || !taosCheckChecksumWhole((uint8_t *)pReadH->pBuf, pFile->info.len)) {
+  if (ret < pFile->info.len || !taosCheckChecksumWhole((uint8_t *)(pReadH->pBuf), pFile->info.len)) {
     tsdbError("vgId:%d block idx part is corrupted in file %s, offset %u len %u", REPO_ID(pRepo), pFile->fname,
               pFile->info.offset, pFile->info.len);
     terrno = TSDB_CODE_TDB_FILE_CORRUPTED;
@@ -107,13 +141,53 @@ int tsdbLoadBlockIdx(SReadHandle *pReadH) {
     return -1;
   }
 
+  pReadH->cBlockIdx = 0;
+
   return 0;
 }
 
 int tsdbSetReadTable(SReadHandle *pReadH, STable *pTable) {
+  ASSERT(pTable != NULL);
+
   pReadH->pTable = pTable;
-  // TODO
-  // pReadH->pCurBlockIdx = NULL;
+
+  STSchema *pSchema = tsdbGetTableSchemaImpl(pTable, false, false, -1);
+  ASSERT(pSchema != NULL);
+
+  if (tdInitDataCols(pReadH->pDataCols[0], pSchema) < 0 || tdInitDataCols(pReadH->pDataCols[1], pSchema) < 0) {
+    terrno = TSDB_CODE_TDB_OUT_OF_MEMORY;
+    return -1;
+  }
+
+  if (pReadH->nBlockIdx > 0) {
+    ASSERT(pReadH->cBlockIdx <= pReadH->nBlockIdx);
+
+    while (true) {
+      if (pReadH->cBlockIdx >= pReadH->nBlockIdx) {
+        pReadH->pCurBlockIdx = NULL;
+        break;
+      }
+
+      SBlockIdx *pBlockIdx = pReadH->pBlockIdx + pReadH->cBlockIdx;
+      if (pBlockIdx->tid == TABLE_TID(pTable)) {
+        if (pBlockIdx->uid == TABLE_UID(pTable)) {
+          pReadH->pCurBlockIdx = pBlockIdx;
+        } else {
+          pReadH->pCurBlockIdx = NULL;
+        }
+        pReadH->cBlockIdx++;
+        break;
+      } else if (pBlockIdx->tid < TABLE_TID(pTable)) {
+        pReadH->cBlockIdx++;
+      } else {
+        pReadH->pCurBlockIdx = NULL;
+        break;
+      }
+    }
+  } else {
+    pReadH->pCurBlockIdx = NULL;
+  }
+
   return 0;
 }
 
@@ -132,12 +206,13 @@ int tsdbLoadBlockInfo(SReadHandle *pReadH) {
   }
 
   if (lseek(pFile->fd, pBlockIdx->offset, SEEK_SET) < 0) {
-    tsdbError("vgId:%d failed to lseek file %s since %s", REPO_ID(pRepo), pFile->fname, strerror(errno));
+    tsdbError("vgId:%d failed to lseek file %s to offset %u since %s", REPO_ID(pRepo), pFile->fname, pBlockIdx->offset,
+              strerror(errno));
     terrno = TAOS_SYSTEM_ERROR(errno);
     return -1;
   }
 
-  ssize_t ret = taosTRead(pFile->fd, (void *)pReadH->pBlockInfo, pBlockIdx->len);
+  ssize_t ret = taosTRead(pFile->fd, (void *)(pReadH->pBlockInfo), pBlockIdx->len);
   if (ret < 0) {
     tsdbError("vgId:%d failed to read block info part of table %s from file %s since %s", REPO_ID(pRepo),
               TABLE_CHAR_NAME(pReadH->pTable), pFile->fname, strerror(errno));
@@ -146,8 +221,8 @@ int tsdbLoadBlockInfo(SReadHandle *pReadH) {
   }
 
   if (ret < pBlockIdx->len || tsdbVerifyBlockInfo(pReadH->pBlockInfo, pBlockIdx) < 0) {
-    tsdbError("vgId:%d table %s block info part is corrupted from file %s since %s", REPO_ID(pRepo),
-              TABLE_CHAR_NAME(pReadH->pTable), pFile->fname, strerror(errno));
+    tsdbError("vgId:%d table %s block info part is corrupted from file %s", REPO_ID(pRepo),
+              TABLE_CHAR_NAME(pReadH->pTable), pFile->fname);
     terrno = TSDB_CODE_TDB_FILE_CORRUPTED;
     return -1;
   }
@@ -198,6 +273,49 @@ int tsdbLoadBlockDataCols(SReadHandle *pReadH, SBlock *pBlock, SBlockInfo *pBloc
     if (tdMergeDataCols(pReadH->pDataCols[0], pReadH->pDataCols[1], pReadH->pDataCols[1]->numOfRows) < 0) goto _err;
   }
 
+  ASSERT(pReadH->pDataCols[0]->numOfRows == pBlock->numOfRows);
+  ASSERT(dataColsKeyFirst(pReadH->pDataCols[0]) == pBlock->keyFirst);
+  ASSERT(dataColsKeyLast(pReadH->pDataCols[0]) == pBlock->keyLast);
+
+  return 0;
+}
+
+int tsdbLoadBlockDataInfo(SReadHandle *pReadH, SBlock *pBlock) {
+  ASSERT(pBlock->numOfSubBlocks <= 1);
+
+  STsdbRepo *pRepo = pReadH->pRepo;
+  SFile *    pFile =
+      (pBlock->last) ? TSDB_READ_FILE(pReadH, TSDB_FILE_TYPE_LAST) : TSDB_READ_FILE(pReadH, TSDB_FILE_TYPE_DATA);
+
+  if (lseek(pFile->fd, pBlock->offset, SEEK_SET) < 0)  {
+    tsdbError("vgId:%d failed to lseek file %s to offset %" PRId64 " since %s", REPO_ID(pRepo), pFile->fname,
+              pBlock->offset, strerror(errno));
+    terrno = TAOS_SYSTEM_ERROR(errno);
+    return -1;
+  }
+
+  int tsize = TSDB_BLOCK_DATA_LEN(pBlock->numOfCols);
+  if (tsdbAllocBuf(&(pReadH->pBlockData), tsize) < 0) {
+    terrno = TSDB_CODE_TDB_OUT_OF_MEMORY;
+    return -1;
+  }
+
+  int ret = taosTRead(pFile->fd, tsize);
+  if (ret < 0) {
+    tsdbError("vgId:%d failed to read block data info part from file %s offset %" PRId64 " len %d since %s",
+              REPO_ID(pRepo), pFile->fname, pBlock->offset, tsize, strerror(errno));
+    terrno = TAOS_SYSTEM_ERROR(errno);
+    return -1;
+  }
+
+  if (ret < tsize || !taosCheckChecksumWhole((uint8_t *)(pReadH->pBlockData), tsize)) {
+    tsdbError("vgId:%d block data info part is corrupted in file %s offset %" PRId64 " len %d", REPO_ID(pRepo),
+              pFile->fname, pBlock->offset, tsize);
+    terrno = TSDB_CODE_TDB_FILE_CORRUPTED;
+    return -1;
+  }
+
+  ASSERT(pReadH->pBlockData->numOfCols == pBlock->numOfCols);
   return 0;
 }
 
@@ -214,15 +332,16 @@ static int tsdbLoadBlockDataImpl(SReadHandle *pReadH, SBlock *pBlock, SDataCols
   }
 
   if (lseek(pFile->fd, pBlock->offset, SEEK_SET) < 0) {
-    tsdbError("vgId:%d failed to lseek file %s since %s", REPO_ID(pRepo), pFile->fname, strerror(errno));
+    tsdbError("vgId:%d failed to lseek file %s to offset %" PRId64 " since %s", REPO_ID(pRepo), pFile->fname,
+              pBlock->offset, strerror(errno));
     terrno = TAOS_SYSTEM_ERROR(errno);
     return -1;
   }
 
-  int ret = taosTRead(pFile->fd, (void *)pReadH->pBuf, pBlock->len);
+  int ret = taosTRead(pFile->fd, (void *)(pReadH->pBuf), pBlock->len);
   if (ret < 0) {
-    tsdbError("vgId:%d failed to read block data part from file %s since %s", REPO_ID(pRepo), pFile->fname,
-              strerror(errno));
+    tsdbError("vgId:%d failed to read block data part from file %s at offset %" PRId64 " len %d since %s",
+              REPO_ID(pRepo), pFile->fname, pBlock->offset, pBlock->len, strerror(errno));
     terrno = TAOS_SYSTEM_ERROR(errno);
     return -1;
   }
@@ -240,6 +359,7 @@ static int tsdbLoadBlockDataImpl(SReadHandle *pReadH, SBlock *pBlock, SDataCols
   ASSERT(pBlockData->numOfCols = pBlock->numOfCols);
 
   tdResetDataCols(pDataCols);
+  ASSERT(pBlock->numOfRows <= pDataCols->maxPoints);
   pDataCols->numOfRows = pBlock->numOfRows;
 
   int ccol = 0;
@@ -269,7 +389,7 @@ static int tsdbLoadBlockDataImpl(SReadHandle *pReadH, SBlock *pBlock, SDataCols
       if (pBlock->algorithm == TWO_STAGE_COMP) {  // extend compression buffer
         int zsize = pDataCol->bytes * pBlock->numOfRows + COMP_OVERFLOW_BYTES;
         if (pDataCol->type == TSDB_DATA_TYPE_BINARY || pDataCol->type == TSDB_DATA_TYPE_NCHAR) {
-          zsize += (sizeof(VarDataLenT) * pCompBlock->numOfRows);
+          zsize += (sizeof(VarDataLenT) * pBlock->numOfRows);
         }
 
         if (tsdbAllocBuf(&(pReadH->pCBuf), zsize) < 0) {
@@ -280,7 +400,7 @@ static int tsdbLoadBlockDataImpl(SReadHandle *pReadH, SBlock *pBlock, SDataCols
       if (tsdbCheckAndDecodeColumnData(pDataCol, POINTER_SHIFT(pBlockData, tsize + toffset), tlen, pBlock->algorithm,
                                        pBlock->numOfRows, pDataCols->maxPoints, pReadH->pCBuf,
                                        (int32_t)taosTSizeof(pReadH->pCBuf)) < 0) {
-        tsdbError("vgId:%d file %s is broken at column %d block offset %" PRId64 " column offset %d", REPO_ID(pRepo),
+        tsdbError("vgId:%d file %s is corrupted at column %d block offset %" PRId64 " column offset %d", REPO_ID(pRepo),
                   pFile->fname, tcolId, (int64_t)pBlock->offset, toffset);
         return -1;
       }
@@ -305,26 +425,27 @@ static int tsdbLoadBlockDataColsImpl(SReadHandle *pReadH, SBlock *pBlock, SDataC
 
   SFile *pFile =
       pBlock->last ? TSDB_READ_FILE(pReadH, TSDB_FILE_TYPE_LAST) : TSDB_READ_FILE(pReadH, TSDB_FILE_TYPE_DATA);
-  SBlockCol compCol = {0};
+  SBlockCol blockCol = {0};
 
   // If only load timestamp column, no need to load SBlockData part
-  if (numOfColIds > 1 && tsdbLoadCompData(pHelper, pCompBlock, NULL) < 0) goto _err;
+  if (numOfColIds > 1 && tsdbLoadBlockDataInfo(pReadH, pBlock) < 0) return -1;
 
-  pDataCols->numOfRows = pCompBlock->numOfRows;
+  tdResetDataCols(pDataCols);
+  pDataCols->numOfRows = pBlock->numOfRows;
 
   int dcol = 0;
   int ccol = 0;
   for (int i = 0; i < numOfColIds; i++) {
-    int16_t   colId = colIds[i];
-    SDataCol *pDataCol = NULL;
-    SBlockCol *pCompCol = NULL;
+    int16_t    colId = colIds[i];
+    SDataCol * pDataCol = NULL;
+    SBlockCol *pBlockCol = NULL;
 
     while (true) {
       if (dcol >= pDataCols->numOfCols) {
         pDataCol = NULL;
         break;
       }
-      pDataCol = &pDataCols->cols[dcol];
+      pDataCol = &(pDataCols->cols[dcol]);
       if (pDataCol->colId > colId) {
         pDataCol = NULL;
         break;
@@ -338,52 +459,49 @@ static int tsdbLoadBlockDataColsImpl(SReadHandle *pReadH, SBlock *pBlock, SDataC
     ASSERT(pDataCol->colId == colId);
 
     if (colId == 0) {  // load the key row
-      compCol.colId = colId;
-      compCol.len = pCompBlock->keyLen;
-      compCol.type = pDataCol->type;
-      compCol.offset = TSDB_KEY_COL_OFFSET;
-      pCompCol = &compCol;
+      blockCol.colId = colId;
+      blockCol.len = pBlock->keyLen;
+      blockCol.type = pDataCol->type;
+      blockCol.offset = TSDB_KEY_COL_OFFSET;
+      pBlockCol = &blockCol;
     } else {  // load non-key rows
       while (true) {
-        if (ccol >= pCompBlock->numOfCols) {
-          pCompCol = NULL;
+        if (ccol >= pBlock->numOfCols) {
+          pBlockCol = NULL;
           break;
         }
 
-        pCompCol = &(pHelper->pCompData->cols[ccol]);
-        if (pCompCol->colId > colId) {
-          pCompCol = NULL;
+        pBlockCol = &(pReadH->pBlockData->cols[ccol]);
+        if (pBlockCol->colId > colId) {
+          pBlockCol = NULL;
           break;
         } else {
           ccol++;
-          if (pCompCol->colId == colId) break;
+          if (pBlockCol->colId == colId) break;
         }
       }
 
-      if (pCompCol == NULL) {
-        dataColSetNEleNull(pDataCol, pCompBlock->numOfRows, pDataCols->maxPoints);
+      if (pBlockCol == NULL) {
+        dataColSetNEleNull(pDataCol, pBlock->numOfRows, pDataCols->maxPoints);
         continue;
       }
 
-      ASSERT(pCompCol->colId == pDataCol->colId);
+      ASSERT(pBlockCol->colId == pDataCol->colId);
     }
 
-    if (tsdbLoadColData(pHelper, pFile, pCompBlock, pCompCol, pDataCol) < 0) goto _err;
+    if (tsdbLoadColData(pReadH, pFile, pBlock, pBlockCol, pDataCol) < 0) return -1;
   }
 
   return 0;
-
-_err:
-  return -1;
 }
 
 static int tsdbDecodeBlockIdxArray(SReadHandle *pReadH) {
-  void *pBuf = pReadH->pBuf;
-  SFile *pFile = &(pReadH->fGroup.files[TSDB_FILE_TYPE_HEAD]);
+  void * pBuf = pReadH->pBuf;
+  SFile *pFile = TSDB_READ_FILE(pReadH, TSDB_FILE_TYPE_HEAD);
 
   pReadH->nBlockIdx = 0;
   while (POINTER_DISTANCE(pBuf, pReadH->pBuf) < (int)(pFile->info.len - sizeof(TSCKSUM))) {
-    if (tsdbAllocBuf(&((void *)(pReadH->pBlockIdx), sizeof(SBlockIdx) * (pReadH->nBlockIdx + 1))) < 0) {
+    if (tsdbAllocBuf(&((void *)(pReadH->pBlockIdx)), sizeof(SBlockIdx) * (pReadH->nBlockIdx + 1)) < 0) {
       terrno = TSDB_CODE_TDB_OUT_OF_MEMORY;
       return -1;
     }
@@ -391,7 +509,7 @@ static int tsdbDecodeBlockIdxArray(SReadHandle *pReadH) {
     pBuf = tsdbDecodeBlockIdx(pBuf, &(pReadH->pBlockIdx[pReadH->nBlockIdx]));
     if (pBuf == NULL) {
       tsdbError("vgId:%d failed to decode block idx part from file %s", REPO_ID(pRepo), pFile->fname);
-      terrno = TSDB_CODE_TDB_OUT_OF_MEMORY;
+      terrno = TSDB_CODE_TDB_FILE_CORRUPTED;
       return -1;
     }
 
@@ -418,14 +536,14 @@ static int tsdbAllocBuf(void **ppBuf, int size) {
 static int tsdbVerifyBlockInfo(SBlockInfo *pBlockInfo, SBlockIdx *pBlockIdx) {
   if (!taosCheckChecksumWhole((uint8_t *)pBlockInfo, pBlockIdx->len)) return -1;
   if (pBlockInfo->delimiter != TSDB_FILE_DELIMITER || pBlockInfo->uid != pBlockIdx->uid ||
-      pBlockInfo->tid != pBlockIdx->tid)
+      pBlockInfo->tid != pBlockIdx->tid) {
     return -1;
+  }
   return 0;
 }
 
-static int tsdbCheckAndDecodeColumnData(SDataCol *pDataCol, char *content, int32_t len, int8_t comp, int numOfRows,
-                                        int maxPoints, char *buffer, int bufferSize) {
-  // Verify by checksum
+static int tsdbCheckAndDecodeColumnData(SDataCol *pDataCol, void *content, int32_t len, int8_t comp, int numOfRows,
+                                        int maxPoints, char *buffer, int bsize) {
   if (!taosCheckChecksumWhole((uint8_t *)content, len)) {
     terrno = TSDB_CODE_TDB_FILE_CORRUPTED;
     return -1;
@@ -435,16 +553,18 @@ static int tsdbCheckAndDecodeColumnData(SDataCol *pDataCol, char *content, int32
   if (comp) {
     // // Need to decompress
     int tlen = (*(tDataTypeDesc[pDataCol->type].decompFunc))(content, len - sizeof(TSCKSUM), numOfRows, pDataCol->pData,
-                                                             pDataCol->spaceSize, comp, buffer, bufferSize);
+                                                             pDataCol->spaceSize, comp, buffer, bsize);
     if (tlen <= 0) {
-      tsdbError("Failed to decompress column, file corrupted, len:%d comp:%d numOfRows:%d maxPoints:%d bufferSize:%d",
-                len, comp, numOfRows, maxPoints, bufferSize);
+      tsdbError("failed to decompress column, file corrupted, len:%d comp:%d numOfRows:%d maxPoints:%d bsize:%d", len,
+                comp, numOfRows, maxPoints, bsize);
       terrno = TSDB_CODE_TDB_FILE_CORRUPTED;
       return -1;
     }
     pDataCol->len = tlen;
     if (pDataCol->type == TSDB_DATA_TYPE_BINARY || pDataCol->type == TSDB_DATA_TYPE_NCHAR) {
       dataColSetOffset(pDataCol, numOfRows);
+    } else {
+      ASSERT(pDataCol->len == pDataCol->bytes * numOfRows);
     }
   } else {
     // No need to decompress, just memcpy it
@@ -452,46 +572,55 @@ static int tsdbCheckAndDecodeColumnData(SDataCol *pDataCol, char *content, int32
     memcpy(pDataCol->pData, content, pDataCol->len);
     if (pDataCol->type == TSDB_DATA_TYPE_BINARY || pDataCol->type == TSDB_DATA_TYPE_NCHAR) {
       dataColSetOffset(pDataCol, numOfRows);
+    } else {
+      ASSERT(pDataCol->len == pDataCol->bytes * numOfRows);
     }
   }
   return 0;
 }
 
-static int tsdbLoadColData(SRWHelper *pHelper, SFile *pFile, SBlock *pCompBlock, SBlockCol *pCompCol,
+static int tsdbLoadColData(SReadHandle *pReadH, SFile *pFile, SBlock *pBlock, SBlockCol *pBlockCol,
                            SDataCol *pDataCol) {
-  ASSERT(pDataCol->colId == pCompCol->colId);
-  int tsize = pDataCol->bytes * pCompBlock->numOfRows + COMP_OVERFLOW_BYTES;
-  pHelper->pBuffer = taosTRealloc(pHelper->pBuffer, pCompCol->len);
-  if (pHelper->pBuffer == NULL) {
-    terrno = TSDB_CODE_TDB_OUT_OF_MEMORY;
-    return -1;
-  }
+  ASSERT(pDataCol->colId == pBlockCol->colId);
 
-  pHelper->compBuffer = taosTRealloc(pHelper->compBuffer, tsize);
-  if (pHelper->compBuffer == NULL) {
+  STsdbRepo *pRepo = pReadH->pRepo;
+  STsdbCfg * pCfg = &(pRepo->config);
+
+  if (tsdbAllocBuf(&(pReadH->pBuf), pBlockCol->len) < 0) {
     terrno = TSDB_CODE_TDB_OUT_OF_MEMORY;
     return -1;
   }
 
-  int64_t offset = pCompBlock->offset + TSDB_GET_COMPCOL_LEN(pCompBlock->numOfCols) + pCompCol->offset;
+  int64_t offset = pBlock->offset + TSDB_GET_COMPCOL_LEN(pBlock->numOfCols) + pBlockCol->offset;
   if (lseek(pFile->fd, (off_t)offset, SEEK_SET) < 0) {
-    tsdbError("vgId:%d failed to lseek file %s since %s", REPO_ID(pHelper->pRepo), pFile->fname, strerror(errno));
+    tsdbError("vgId:%d failed to lseek file %s since %s", REPO_ID(pRepo), pFile->fname, strerror(errno));
     terrno = TAOS_SYSTEM_ERROR(errno);
     return -1;
   }
 
-  if (taosTRead(pFile->fd, pHelper->pBuffer, pCompCol->len) < pCompCol->len) {
-    tsdbError("vgId:%d failed to read %d bytes from file %s since %s", REPO_ID(pHelper->pRepo), pCompCol->len, pFile->fname,
-              strerror(errno));
+  int ret = taosTRead(pFile->fd, pReadH->pBuf, pBlockCol->len);
+  if (ret < 0) {
+    tsdbError("vgId:%d failed to read %d bytes from file %s since %s", REPO_ID(pRepo), pBlockCol->len,
+              pFile->fname, strerror(errno));
     terrno = TAOS_SYSTEM_ERROR(errno);
     return -1;
   }
 
-  if (tsdbCheckAndDecodeColumnData(pDataCol, pHelper->pBuffer, pCompCol->len, pCompBlock->algorithm,
-                                   pCompBlock->numOfRows, pHelper->pRepo->config.maxRowsPerFileBlock,
-                                   pHelper->compBuffer, (int32_t)taosTSizeof(pHelper->compBuffer)) < 0) {
-    tsdbError("vgId:%d file %s is broken at column %d offset %" PRId64, REPO_ID(pHelper->pRepo), pFile->fname,
-              pCompCol->colId, offset);
+  if (pBlock->algorithm == TWO_STAGE_COMP) {  // extend compression buffer
+    int zsize = pDataCol->bytes * pBlock->numOfRows + COMP_OVERFLOW_BYTES;
+    if (pDataCol->type == TSDB_DATA_TYPE_BINARY || pDataCol->type == TSDB_DATA_TYPE_NCHAR) {
+      zsize += (sizeof(VarDataLenT) * pBlock->numOfRows);
+    }
+
+    if (tsdbAllocBuf(&(pReadH->pCBuf), zsize) < 0) {
+      terrno = TSDB_CODE_TDB_OUT_OF_MEMORY;
+      return -1;
+    }
+  }
+  if (tsdbCheckAndDecodeColumnData(pDataCol, pReadH->pBuf, pBlockCol->len, pBlock->algorithm, pBlock->numOfRows,
+                                   pCfg->maxRowsPerFileBlock, pReadH->pCBuf, (int32_t)taosTSizeof(pReadH->pCBuf)) < 0) {
+    tsdbError("vgId:%d file %s is broken at column %d offset %" PRId64, REPO_ID(pRepo), pFile->fname,
+              pBlockCol->colId, offset);
     return -1;
   }
 
diff --git a/src/tsdb/src/tsdbUtil.c b/src/tsdb/src/tsdbUtil.c
index 6ea28e580e2db677686272534669971221a709e1..18a23284df2e23d01026f6af21d80226290c535f 100644
--- a/src/tsdb/src/tsdbUtil.c
+++ b/src/tsdb/src/tsdbUtil.c
@@ -104,4 +104,10 @@ void *tsdbDecodeBlockIdx(void *buf, SBlockIdx *pBlockIdx) {
   pBlockIdx->maxKey = (TSKEY)maxKey;
 
   return buf;
+}
+
+void tsdbResetFGroupFd(SFileGroup *pFGroup) {
+  for (int type = 0; type < TSDB_FILE_TYPE_MAX; type++) {
+    pFGroup->files[type].fd = -1;
+  }
 }
\ No newline at end of file