diff --git a/source/libs/executor/src/scanoperator.c b/source/libs/executor/src/scanoperator.c
index b52f942438..34a70f28e4 100644
--- a/source/libs/executor/src/scanoperator.c
+++ b/source/libs/executor/src/scanoperator.c
@@ -3318,6 +3318,7 @@ _error:
 // TODO: get block from tsdReader function, with task killed, func_data all filter out, skip, finish
 // TODO: error processing, memory freeing
 // TODO: add log for error and perf
+// TODO: tsdb reader open/close dynamically
 
 static int32_t subTblRowCompareFn(const void* pLeft, const void* pRight, void* param) {
   int32_t left = *(int32_t*)pLeft;
@@ -3350,11 +3351,14 @@ static int32_t fetchNextSubTableBlockFromReader(SOperatorInfo* pOperator, STmsSu
 
   blockDataCleanup(pInput->pBlock);
 
+  pInfo->base.dataReader = pInput->pReader;
+
   while (true) {
     bool hasNext = false;
     int32_t code = pAPI->tsdReader.tsdNextDataBlock(pInput->pReader, &hasNext);
     if (code != 0) {
       pAPI->tsdReader.tsdReaderReleaseDataBlock(pInput->pReader);
+      pInfo->base.dataReader = NULL;
       T_LONG_JMP(pTaskInfo->env, code);
     }
     if (!hasNext || isTaskKilled(pTaskInfo)) {
@@ -3367,6 +3371,7 @@ static int32_t fetchNextSubTableBlockFromReader(SOperatorInfo* pOperator, STmsSu
     uint32_t status = 0;
     code = loadDataBlock(pOperator, &pInfo->base, pInput->pBlock, &status);
     if (code != 0) {
+      pInfo->base.dataReader = NULL;
       T_LONG_JMP(pTaskInfo->env, code);
     }
     if (status == FUNC_DATA_REQUIRED_ALL_FILTEROUT) {
@@ -3379,8 +3384,10 @@ static int32_t fetchNextSubTableBlockFromReader(SOperatorInfo* pOperator, STmsSu
     *pSubTableHasBlock = true;
     pInput->pBlock->info.id.groupId = tableListGetTableGroupId(pInfo->base.pTableListInfo, pInput->pBlock->info.id.uid);
     pOperator->resultInfo.totalRows += pInput->pBlock->info.rows;
+    pInfo->base.dataReader = NULL;
     return TSDB_CODE_SUCCESS;
   }
+  pInfo->base.dataReader = NULL;
   *pSubTableHasBlock = false;
   return TSDB_CODE_SUCCESS;
 }
@@ -3488,7 +3495,7 @@ static int32_t initSubTableInputs(SOperatorInfo* pOperator, STableMergeScanInfo*
     pInput->type = SUB_TABLE_MEM_BLOCK;
     pInput->pBlock = createOneDataBlock(pInfo->pResBlock, false);
     STableKeyInfo* keyInfo = tableListGetInfo(pInfo->base.pTableListInfo, i + pInfo->tableStartIndex);
-    pAPI->tsdReader.tsdReaderOpen(pHandle->vnode, &pInfo->base.cond, keyInfo, 1, pInfo->pReaderBlock,
+    pAPI->tsdReader.tsdReaderOpen(pHandle->vnode, &pInfo->base.cond, keyInfo, 1, pInput->pBlock,
                                   (void**)&pInput->pReader, GET_TASKID(pTaskInfo), NULL);
     bool hasNext = true;
     fetchNextSubTableBlockFromReader(pOperator, pInput, &hasNext);
@@ -3638,7 +3645,7 @@ static int32_t stopSubTablesTableMergeScan(STableMergeScanInfo* pInfo) {
   if (pSubTblsInfo != NULL) {
     tMergeTreeDestroy(&pSubTblsInfo->pTree);
 
-    for (int32_t i = 0; i <= pSubTblsInfo->numSubTables; ++i) {
+    for (int32_t i = 0; i < pSubTblsInfo->numSubTables; ++i) {
       STmsSubTableInput* pInput =  pSubTblsInfo->aInputs + i;
 
       blockDataDestroy(pInput->pBlock);
@@ -4272,7 +4279,7 @@ SOperatorInfo* createTableMergeScanOperatorInfo(STableScanPhysiNode* pTableScanN
                   pInfo, pTaskInfo);
   pOperator->exprSupp.numOfExprs = numOfCols;
 
-  pOperator->fpSet = createOperatorFpSet(optrDummyOpenFn, doTableMergeScan, NULL, destroyTableMergeScanOperatorInfo,
+  pOperator->fpSet = createOperatorFpSet(optrDummyOpenFn, doTableMergeScanSubTables, NULL, destroyTableMergeScanOperatorInfo,
                                          optrDefaultBufFn, getTableMergeScanExplainExecInfo, optrDefaultGetNextExtFn, NULL);
   pOperator->cost.openCost = 0;
   return pOperator;