diff --git a/src/query/src/qExecutor.c b/src/query/src/qExecutor.c
index 8e0537016a..8156967d5d 100644
--- a/src/query/src/qExecutor.c
+++ b/src/query/src/qExecutor.c
@@ -4339,7 +4339,9 @@ static void sequentialTableProcess(SQInfo *pQInfo) {
       taosArrayDestroy(s);
 
       // here we simply set the first table as current table
-      pQuery->current = (STableQueryInfo*) GET_TABLEGROUP(pQInfo, 0);
+      SArray* first = GET_TABLEGROUP(pQInfo, pQInfo->groupIndex);
+      pQuery->current = taosArrayGetP(first, 0);
+
       scanOneTableDataBlocks(pRuntimeEnv, pQuery->current->lastKey);
       
       int64_t numOfRes = getNumOfResult(pRuntimeEnv);
@@ -5799,7 +5801,7 @@ static void freeQInfo(SQInfo *pQInfo) {
   // todo refactor, extract method to destroytableDataInfo
   int32_t numOfGroups = GET_NUM_OF_TABLEGROUP(pQInfo);
   for (int32_t i = 0; i < numOfGroups; ++i) {
-    SArray *p = GET_TABLEGROUP(pQInfo, i);;
+    SArray *p = GET_TABLEGROUP(pQInfo, i);
 
     size_t num = taosArrayGetSize(p);
     for(int32_t j = 0; j < num; ++j) {
diff --git a/src/tsdb/src/tsdbRead.c b/src/tsdb/src/tsdbRead.c
index cc2b6757fc..056c71e8b8 100644
--- a/src/tsdb/src/tsdbRead.c
+++ b/src/tsdb/src/tsdbRead.c
@@ -1515,7 +1515,8 @@ bool tsdbNextDataBlock(TsdbQueryHandleT* pHandle) {
       pSecQueryHandle->outputCapacity = ((STsdbRepo*)pSecQueryHandle->pTsdb)->config.maxRowsPerFileBlock;
   
       tsdbInitReadHelper(&pSecQueryHandle->rhelper, (STsdbRepo*) pSecQueryHandle->pTsdb);
-  
+      tsdbTakeMemSnapshot(pSecQueryHandle->pTsdb, &pSecQueryHandle->mem, &pSecQueryHandle->imem);
+
       // allocate buffer in order to load data blocks from file
       int32_t numOfCols = QH_GET_NUM_OF_COLS(pQueryHandle);