diff --git a/source/dnode/vnode/src/inc/tsdb.h b/source/dnode/vnode/src/inc/tsdb.h
index f802575c4ada92db2af51a2c6c3b226dd23d1ad8..3d4cad4bd1353cd73191d1e8f8d4d2c8ccac05c7 100644
--- a/source/dnode/vnode/src/inc/tsdb.h
+++ b/source/dnode/vnode/src/inc/tsdb.h
@@ -65,6 +65,7 @@ typedef struct SSmaInfo      SSmaInfo;
 typedef struct SBlockCol     SBlockCol;
 typedef struct SVersionRange SVersionRange;
 typedef struct SLDataIter    SLDataIter;
+typedef struct SQueryNode    SQueryNode;
 
 #define TSDB_FILE_DLMT     ((uint32_t)0xF00AFA0F)
 #define TSDB_MAX_SUBBLOCKS 8
@@ -206,8 +207,8 @@ 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);
-int32_t  tsdbRefMemTable(SMemTable *pMemTable, STsdbReader *pReader);
-int32_t  tsdbUnrefMemTable(SMemTable *pMemTable, STsdbReader *pReader);
+int32_t  tsdbRefMemTable(SMemTable *pMemTable, void *pQueryHandle, SQueryNode **ppNode);
+int32_t  tsdbUnrefMemTable(SMemTable *pMemTable, SQueryNode *pNode);
 SArray  *tsdbMemTableGetTbDataArray(SMemTable *pMemTable);
 // STbDataIter
 int32_t  tsdbTbDataIterCreate(STbData *pTbData, TSDBKEY *pFrom, int8_t backward, STbDataIter **ppIter);
@@ -365,6 +366,12 @@ struct STbData {
   STbData     *next;
 };
 
+struct SQueryNode {
+  SQueryNode  *pNext;
+  SQueryNode **ppNext;
+  void        *pQueryHandle;
+};
+
 struct SMemTable {
   SRWLatch         latch;
   STsdb           *pTsdb;
@@ -381,7 +388,7 @@ struct SMemTable {
     int32_t   nBucket;
     STbData **aBucket;
   };
-  STsdbReader *pReaderList;
+  SQueryNode *qList;
 };
 
 struct TSDBROW {
@@ -592,9 +599,11 @@ struct SDelFWriter {
 };
 
 struct STsdbReadSnap {
-  SMemTable *pMem;
-  SMemTable *pIMem;
-  STsdbFS    fs;
+  SMemTable  *pMem;
+  SQueryNode *pNode;
+  SMemTable  *pIMem;
+  SQueryNode *pINode;
+  STsdbFS     fs;
 };
 
 struct SDataFWriter {
diff --git a/source/dnode/vnode/src/tsdb/tsdbMemTable.c b/source/dnode/vnode/src/tsdb/tsdbMemTable.c
index 7348b284ab75c01183a0c3d51933d601874f921d..a78021d69737d98073f3e8c2f24265bfa00d693b 100644
--- a/source/dnode/vnode/src/tsdb/tsdbMemTable.c
+++ b/source/dnode/vnode/src/tsdb/tsdbMemTable.c
@@ -629,24 +629,35 @@ _err:
 
 int32_t tsdbGetNRowsInTbData(STbData *pTbData) { return pTbData->sl.size; }
 
-int32_t tsdbRefMemTable(SMemTable *pMemTable, STsdbReader *pReader) {
+int32_t tsdbRefMemTable(SMemTable *pMemTable, void *pQueryHandle, SQueryNode **ppNode) {
   int32_t code = 0;
 
   int32_t nRef = atomic_fetch_add_32(&pMemTable->nRef, 1);
   ASSERT(nRef > 0);
 
-  // register handle (todo)
-  if (pReader) {
+  // register handle
+  *ppNode = taosMemoryMalloc(sizeof(SQueryNode));
+  if (*ppNode == NULL) {
+    code = TSDB_CODE_OUT_OF_MEMORY;
+    goto _exit;
   }
+  (*ppNode)->pQueryHandle = pQueryHandle;
+  (*ppNode)->pNext = pMemTable->qList;
+  (*ppNode)->ppNext = &pMemTable->qList;
+  pMemTable->qList = *ppNode;
 
+_exit:
   return code;
 }
 
-int32_t tsdbUnrefMemTable(SMemTable *pMemTable, STsdbReader *pReader) {
+int32_t tsdbUnrefMemTable(SMemTable *pMemTable, SQueryNode *pNode) {
   int32_t code = 0;
 
-  // unregister handle (todo)
-  if (pReader) {
+  // unregister handle
+  if (pNode) {
+    pNode->pNext->ppNext = pNode->ppNext;
+    *pNode->ppNext = pNode->pNext;
+    taosMemoryFree(pNode);
   }
 
   int32_t nRef = atomic_sub_fetch_32(&pMemTable->nRef, 1);
diff --git a/source/dnode/vnode/src/tsdb/tsdbRead.c b/source/dnode/vnode/src/tsdb/tsdbRead.c
index bd8d665e94faac8f5baa530925e7bb3f02da9c41..c0e4b4cd5016a8976e0b1de9f2b07aeb26ed9327 100644
--- a/source/dnode/vnode/src/tsdb/tsdbRead.c
+++ b/source/dnode/vnode/src/tsdb/tsdbRead.c
@@ -3879,12 +3879,12 @@ int32_t tsdbTakeReadSnap(STsdbReader* pReader, STsdbReadSnap** ppSnap) {
 
   // take snapshot
   if (pTsdb->mem && (pRange->minVer <= pTsdb->mem->maxVer && pRange->maxVer >= pTsdb->mem->minVer)) {
-    tsdbRefMemTable(pTsdb->mem, pReader);
+    tsdbRefMemTable(pTsdb->mem, pReader, &(*ppSnap)->pNode);
     (*ppSnap)->pMem = pTsdb->mem;
   }
 
   if (pTsdb->imem && (pRange->minVer <= pTsdb->imem->maxVer && pRange->maxVer >= pTsdb->imem->minVer)) {
-    tsdbRefMemTable(pTsdb->imem, pReader);
+    tsdbRefMemTable(pTsdb->imem, pReader, &(*ppSnap)->pINode);
     (*ppSnap)->pIMem = pTsdb->imem;
   }
 
@@ -3912,11 +3912,11 @@ void tsdbUntakeReadSnap(STsdbReader* pReader, STsdbReadSnap* pSnap) {
 
   if (pSnap) {
     if (pSnap->pMem) {
-      tsdbUnrefMemTable(pSnap->pMem, pReader);
+      tsdbUnrefMemTable(pSnap->pMem, pSnap->pNode);
     }
 
     if (pSnap->pIMem) {
-      tsdbUnrefMemTable(pSnap->pIMem, pReader);
+      tsdbUnrefMemTable(pSnap->pIMem, pSnap->pINode);
     }
 
     tsdbFSUnref(pTsdb, &pSnap->fs);