diff --git a/source/dnode/vnode/src/inc/tsdb.h b/source/dnode/vnode/src/inc/tsdb.h
index 48d02d275ea342cbd7ac2f782acc0f22a4e640fa..f802575c4ada92db2af51a2c6c3b226dd23d1ad8 100644
--- a/source/dnode/vnode/src/inc/tsdb.h
+++ b/source/dnode/vnode/src/inc/tsdb.h
@@ -206,8 +206,8 @@ int32_t tsdbDecmprColData(uint8_t *pIn, SBlockCol *pBlockCol, int8_t cmprAlg, in
 int32_t  tsdbMemTableCreate(STsdb *pTsdb, SMemTable **ppMemTable);
 void     tsdbMemTableDestroy(SMemTable *pMemTable);
 STbData *tsdbGetTbDataFromMemTable(SMemTable *pMemTable, tb_uid_t suid, tb_uid_t uid);
-void     tsdbRefMemTable(SMemTable *pMemTable);
-void     tsdbUnrefMemTable(SMemTable *pMemTable);
+int32_t  tsdbRefMemTable(SMemTable *pMemTable, STsdbReader *pReader);
+int32_t  tsdbUnrefMemTable(SMemTable *pMemTable, STsdbReader *pReader);
 SArray  *tsdbMemTableGetTbDataArray(SMemTable *pMemTable);
 // STbDataIter
 int32_t  tsdbTbDataIterCreate(STbData *pTbData, TSDBKEY *pFrom, int8_t backward, STbDataIter **ppIter);
@@ -285,8 +285,8 @@ int32_t tsdbDelFReaderClose(SDelFReader **ppReader);
 int32_t tsdbReadDelData(SDelFReader *pReader, SDelIdx *pDelIdx, SArray *aDelData);
 int32_t tsdbReadDelIdx(SDelFReader *pReader, SArray *aDelIdx);
 // tsdbRead.c ==============================================================================================
-int32_t tsdbTakeReadSnap(STsdb *pTsdb, STsdbReadSnap **ppSnap);
-void    tsdbUntakeReadSnap(STsdb *pTsdb, STsdbReadSnap *pSnap);
+int32_t tsdbTakeReadSnap(STsdbReader *pReader, STsdbReadSnap **ppSnap);
+void    tsdbUntakeReadSnap(STsdbReader *pReader, STsdbReadSnap *pSnap);
 // tsdbMerge.c ==============================================================================================
 int32_t tsdbMerge(STsdb *pTsdb);
 
diff --git a/source/dnode/vnode/src/tsdb/tsdbCache.c b/source/dnode/vnode/src/tsdb/tsdbCache.c
index 8da783a5bd82ccd23fe051e76396489cc6516058..ab4d81568922c01f482196760a26861b71bf7db4 100644
--- a/source/dnode/vnode/src/tsdb/tsdbCache.c
+++ b/source/dnode/vnode/src/tsdb/tsdbCache.c
@@ -847,7 +847,7 @@ static int32_t nextRowIterOpen(CacheNextRowIter *pIter, tb_uid_t uid, STsdb *pTs
 
   tb_uid_t suid = getTableSuidByUid(uid, pTsdb);
 
-  tsdbTakeReadSnap(pTsdb, &pIter->pReadSnap);
+  tsdbTakeReadSnap(NULL /*pTsdb (todo)*/, &pIter->pReadSnap);
 
   STbData *pMem = NULL;
   if (pIter->pReadSnap->pMem) {
@@ -941,7 +941,7 @@ static int32_t nextRowIterClose(CacheNextRowIter *pIter) {
     taosArrayDestroy(pIter->pSkyline);
   }
 
-  tsdbUntakeReadSnap(pIter->pTsdb, pIter->pReadSnap);
+  tsdbUntakeReadSnap(NULL /*pIter->pTsdb (todo)*/, pIter->pReadSnap);
 
 _err:
   return code;
diff --git a/source/dnode/vnode/src/tsdb/tsdbCommit.c b/source/dnode/vnode/src/tsdb/tsdbCommit.c
index a619b9f2e4f827d72f2aad5fd752ae002ac2fc74..05c103deec99794fe11539c902c17e9c47152011 100644
--- a/source/dnode/vnode/src/tsdb/tsdbCommit.c
+++ b/source/dnode/vnode/src/tsdb/tsdbCommit.c
@@ -158,7 +158,7 @@ int32_t tsdbCommit(STsdb *pTsdb) {
     pTsdb->mem = NULL;
     taosThreadRwlockUnlock(&pTsdb->rwLock);
 
-    tsdbUnrefMemTable(pMemTable);
+    tsdbUnrefMemTable(pMemTable, NULL);
     goto _exit;
   }
 
@@ -983,7 +983,7 @@ static int32_t tsdbEndCommit(SCommitter *pCommitter, int32_t eno) {
   // unlock
   taosThreadRwlockUnlock(&pTsdb->rwLock);
 
-  tsdbUnrefMemTable(pMemTable);
+  tsdbUnrefMemTable(pMemTable, NULL);
   tsdbFSDestroy(&pCommitter->fs);
   taosArrayDestroy(pCommitter->aTbDataP);
 
diff --git a/source/dnode/vnode/src/tsdb/tsdbMemTable.c b/source/dnode/vnode/src/tsdb/tsdbMemTable.c
index 0ed143aab92580170ed19bb25c9b048d99459721..7348b284ab75c01183a0c3d51933d601874f921d 100644
--- a/source/dnode/vnode/src/tsdb/tsdbMemTable.c
+++ b/source/dnode/vnode/src/tsdb/tsdbMemTable.c
@@ -629,16 +629,32 @@ _err:
 
 int32_t tsdbGetNRowsInTbData(STbData *pTbData) { return pTbData->sl.size; }
 
-void tsdbRefMemTable(SMemTable *pMemTable) {
+int32_t tsdbRefMemTable(SMemTable *pMemTable, STsdbReader *pReader) {
+  int32_t code = 0;
+
   int32_t nRef = atomic_fetch_add_32(&pMemTable->nRef, 1);
   ASSERT(nRef > 0);
+
+  // register handle (todo)
+  if (pReader) {
+  }
+
+  return code;
 }
 
-void tsdbUnrefMemTable(SMemTable *pMemTable) {
+int32_t tsdbUnrefMemTable(SMemTable *pMemTable, STsdbReader *pReader) {
+  int32_t code = 0;
+
+  // unregister handle (todo)
+  if (pReader) {
+  }
+
   int32_t nRef = atomic_sub_fetch_32(&pMemTable->nRef, 1);
   if (nRef == 0) {
     tsdbMemTableDestroy(pMemTable);
   }
+
+  return code;
 }
 
 static FORCE_INLINE int32_t tbDataPCmprFn(const void *p1, const void *p2) {
diff --git a/source/dnode/vnode/src/tsdb/tsdbRead.c b/source/dnode/vnode/src/tsdb/tsdbRead.c
index 495d2b3070c58824b2231091f0892acc2818a3a0..bd8d665e94faac8f5baa530925e7bb3f02da9c41 100644
--- a/source/dnode/vnode/src/tsdb/tsdbRead.c
+++ b/source/dnode/vnode/src/tsdb/tsdbRead.c
@@ -3354,7 +3354,7 @@ int32_t tsdbReaderOpen(SVnode* pVnode, SQueryTableDataCond* pCond, SArray* pTabl
     goto _err;
   }
 
-  code = tsdbTakeReadSnap(pReader->pTsdb, &pReader->pReadSnap);
+  code = tsdbTakeReadSnap(pReader, &pReader->pReadSnap);
   if (code != TSDB_CODE_SUCCESS) {
     goto _err;
   }
@@ -3378,7 +3378,7 @@ int32_t tsdbReaderOpen(SVnode* pVnode, SQueryTableDataCond* pCond, SArray* pTabl
     STsdbReader*    pPrevReader = pReader->innerReader[0];
     SDataBlockIter* pBlockIter = &pPrevReader->status.blockIter;
 
-    code = tsdbTakeReadSnap(pPrevReader->pTsdb, &pPrevReader->pReadSnap);
+    code = tsdbTakeReadSnap(pPrevReader, &pPrevReader->pReadSnap);
     if (code != TSDB_CODE_SUCCESS) {
       goto _err;
     }
@@ -3435,7 +3435,7 @@ void tsdbReaderClose(STsdbReader* pReader) {
     tsdbDataFReaderClose(&pReader->pFileReader);
   }
 
-  tsdbUntakeReadSnap(pReader->pTsdb, pReader->pReadSnap);
+  tsdbUntakeReadSnap(pReader, pReader->pReadSnap);
 
   taosMemoryFree(pReader->status.uidCheckInfo.tableUidList);
   SIOCostSummary* pCost = &pReader->cost;
@@ -3858,8 +3858,10 @@ 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;
+int32_t tsdbTakeReadSnap(STsdbReader* pReader, STsdbReadSnap** ppSnap) {
+  int32_t        code = 0;
+  STsdb*         pTsdb = pReader->pTsdb;
+  SVersionRange* pRange = &pReader->verRange;
 
   // alloc
   *ppSnap = (STsdbReadSnap*)taosMemoryCalloc(1, sizeof(STsdbReadSnap));
@@ -3876,15 +3878,14 @@ int32_t tsdbTakeReadSnap(STsdb* pTsdb, STsdbReadSnap** ppSnap) {
   }
 
   // take snapshot
-  (*ppSnap)->pMem = pTsdb->mem;
-  (*ppSnap)->pIMem = pTsdb->imem;
-
-  if ((*ppSnap)->pMem) {
-    tsdbRefMemTable((*ppSnap)->pMem);
+  if (pTsdb->mem && (pRange->minVer <= pTsdb->mem->maxVer && pRange->maxVer >= pTsdb->mem->minVer)) {
+    tsdbRefMemTable(pTsdb->mem, pReader);
+    (*ppSnap)->pMem = pTsdb->mem;
   }
 
-  if ((*ppSnap)->pIMem) {
-    tsdbRefMemTable((*ppSnap)->pIMem);
+  if (pTsdb->imem && (pRange->minVer <= pTsdb->imem->maxVer && pRange->maxVer >= pTsdb->imem->minVer)) {
+    tsdbRefMemTable(pTsdb->imem, pReader);
+    (*ppSnap)->pIMem = pTsdb->imem;
   }
 
   // fs
@@ -3906,14 +3907,16 @@ _exit:
   return code;
 }
 
-void tsdbUntakeReadSnap(STsdb* pTsdb, STsdbReadSnap* pSnap) {
+void tsdbUntakeReadSnap(STsdbReader* pReader, STsdbReadSnap* pSnap) {
+  STsdb* pTsdb = pReader->pTsdb;
+
   if (pSnap) {
     if (pSnap->pMem) {
-      tsdbUnrefMemTable(pSnap->pMem);
+      tsdbUnrefMemTable(pSnap->pMem, pReader);
     }
 
     if (pSnap->pIMem) {
-      tsdbUnrefMemTable(pSnap->pIMem);
+      tsdbUnrefMemTable(pSnap->pIMem, pReader);
     }
 
     tsdbFSUnref(pTsdb, &pSnap->fs);