diff --git a/src/tsdb/src/tsdbReadUtil.c b/src/tsdb/src/tsdbReadUtil.c
index 1eb65016b001f39ee5432fc5969f10859d282ef3..54966daf4db458e9c3e5979b1b117a4eb02469b1 100644
--- a/src/tsdb/src/tsdbReadUtil.c
+++ b/src/tsdb/src/tsdbReadUtil.c
@@ -12,10 +12,153 @@
  * You should have received a copy of the GNU Affero General Public License
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  */
+#include <fcntl.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+
 #include "tsdbMain.h"
+#include "tchecksum.h"
 
 typedef struct {
-  SFileGroup fGroup;
-  TSKEY      minKey;
-  TSKEY      maxKey;
+  STsdbRepo * pRepo;
+  SFileGroup  fGroup;
+  TSKEY       minKey;
+  TSKEY       maxKey;
+  SBlockIdx * pBlockIdx;
+  int         nBlockIdx;
+  uint64_t    uid;
+  int32_t     tid;
+  SBlockInfo *pBlockInfo;
+  SDataCols * pDataCols[2];
+  void *      pBuf;
+  void *      pCBuf;
 } SReadHandle;
+
+#define TSDB_READ_FILE(pReadH, type) (&((pReadH)->fGroup.files[(type)]))
+
+int tsdbInitReadHandle(SReadHandle *pReadH, STsdbRepo *pRepo) {
+  pReadH->pRepo = pRepo;
+  return 0;
+}
+
+void tsdbDestroyReadHandle(SReadHandle *pReadH) {
+  // TODO
+}
+
+int tsdbSetAndOpenFGroup(SReadHandle *pReadH, SFileGroup *pFGroup) {
+  STsdbRepo *pRepo = pReadH->pRepo;
+  pReadH->fGroup = *pFGroup;
+
+  for (int type = 0; type < TSDB_FILE_TYPE_MAX; type++) {
+    pReadH->fGroup.files[type].fd = -1;
+  }
+
+  for (int type = 0; type < TSDB_FILE_TYPE_MAX; type++) {
+    SFile *pFile = &(pReadH->fGroup.files[type]);
+
+    if (pFile->fname[0] != '\0') {
+      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));
+        terrno = TAOS_SYSTEM_ERROR(errno);
+        tsdbCloseAndUnsetFile(pReadH);
+        return -1;
+      }
+    }
+  }
+
+  return 0;
+}
+
+void tsdbCloseAndUnsetFile(SReadHandle *pReadH) {
+  for (int type = 0; type < TSDB_FILE_TYPE_MAX; type++) {
+    SFile *pFile = &(pReadH->fGroup.files[type]);
+
+    if (pFile->fd > 0) {
+      (void)close(pFile->fd);
+      pFile->fd = -1;
+    }
+  }
+}
+
+int tsdbLoadBlockIdx(SReadHandle *pReadH) {
+  STsdbRepo *pRepo = pReadH->pRepo;
+  SFile *    pFile = &(pReadH->fGroup.files[TSDB_FILE_TYPE_HEAD]);
+
+  if (pFile->fd < 0 || pFile->info.len == 0) {
+    pReadH->nBlockIdx = 0;
+    return 0;
+  }
+
+  if (tsdbAllocBuf(&(pReadH->pBuf), pFile->info.len) < 0) {
+    terrno = TAOS_SYSTEM_ERROR(errno);
+    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));
+    terrno = TAOS_SYSTEM_ERROR(errno);
+    return -1;
+  }
+
+  ssize_t ret = taosTRead(pFile->fd, pReadH->pBuf, pFile->info.len);
+  if (ret < 0) {
+    tsdbError("vgId:%d failed to read block idx part from file %s since %s", REPO_ID(pRepo), pFile->fname,
+              strerror(errno));
+    terrno = TAOS_SYSTEM_ERROR(errno);
+    return -1;
+  }
+
+  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;
+    return -1;
+  }
+
+  if (tsdbDecodeBlockIdxArray(pReadH) < 0) {
+    tsdbError("vgId:%d error occurs while decoding block idx part from file %s", REPO_ID(pRepo), pFile->fname);
+    terrno = TSDB_CODE_TDB_FILE_CORRUPTED;
+    return -1;
+  }
+
+  return 0;
+}
+
+static int tsdbDecodeBlockIdxArray(SReadHandle *pReadH) {
+  void *pBuf = pReadH->pBuf;
+  SFile *pFile = &(pReadH->fGroup.files[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) {
+      terrno = TSDB_CODE_TDB_OUT_OF_MEMORY;
+      return -1;
+    }
+
+    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;
+      return -1;
+    }
+
+    pReadH->nBlockIdx++;
+    ASSERT(pReadH->nBlockIdx == 1 || (pReadH->pBlockIdx[pReadH->nBlockIdx-1].tid < (pReadH->pBlockIdx[pReadH->nBlockIdx-2].tid));
+  }
+  return 0;
+}
+
+static int tsdbAllocBuf(void **ppBuf, int size) {
+  void *pBuf = *pBuf;
+
+  int tsize = taosTSizeof(pBuf);
+  if (tsize == 0) tsize = 1024;
+
+  while (tsize < size) {
+    tsize *= 2;
+  }
+
+  *ppBuf = taosTRealloc(pBuf, tsize);
+  if (*ppBuf == NULL) return -1;
+}
\ No newline at end of file
diff --git a/src/tsdb/src/tsdbUtil.c b/src/tsdb/src/tsdbUtil.c
index 68ce673331ce8a5db0784b5a496d944365816253..6ea28e580e2db677686272534669971221a709e1 100644
--- a/src/tsdb/src/tsdbUtil.c
+++ b/src/tsdb/src/tsdbUtil.c
@@ -68,4 +68,40 @@ int tsdbGetNextSeqNum(int currentNum) {
   } else {
     return 0;
   }
+}
+
+int tsdbEncodeBlockIdx(void **buf, SBlockIdx *pBlockIdx) {
+  int tlen = 0;
+
+  tlen += taosEncodeVariantI32(buf, pBlockIdx->tid);
+  tlen += taosEncodeVariantU32(buf, pBlockIdx->len);
+  tlen += taosEncodeVariantU32(buf, pBlockIdx->offset);
+  tlen += taosEncodeFixedU8(buf, pBlockIdx->hasLast);
+  tlen += taosEncodeVariantU32(buf, pBlockIdx->numOfBlocks);
+  tlen += taosEncodeFixedU64(buf, pBlockIdx->uid);
+  tlen += taosEncodeFixedU64(buf, pBlockIdx->maxKey);
+
+  return tlen;
+}
+
+void *tsdbDecodeBlockIdx(void *buf, SBlockIdx *pBlockIdx) {
+  uint8_t  hasLast = 0;
+  uint32_t numOfBlocks = 0;
+  uint64_t uid = 0;
+  uint64_t maxKey = 0;
+
+  if ((buf = taosDecodeVariantI32(buf, &(pBlockIdx->tid))) == NULL) return NULL;
+  if ((buf = taosDecodeVariantU32(buf, &(pBlockIdx->len))) == NULL) return NULL;
+  if ((buf = taosDecodeVariantU32(buf, &(pBlockIdx->offset))) == NULL) return NULL;
+  if ((buf = taosDecodeFixedU8(buf, &(hasLast))) == NULL) return NULL;
+  if ((buf = taosDecodeVariantU32(buf, &(numOfBlocks))) == NULL) return NULL;
+  if ((buf = taosDecodeFixedU64(buf, &uid)) == NULL) return NULL;
+  if ((buf = taosDecodeFixedU64(buf, &maxKey)) == NULL) return NULL;
+
+  pBlockIdx->hasLast = hasLast;
+  pBlockIdx->numOfBlocks = numOfBlocks;
+  pBlockIdx->uid = value;
+  pBlockIdx->maxKey = (TSKEY)maxKey;
+
+  return buf;
 }
\ No newline at end of file