[td-1373]

src/query/src/qExecutor.c

@@ -1410,6 +1410,8 @@ static void rowwiseApplyFunctions(SQueryRuntimeEnv *pRuntimeEnv, SDataStatis *pS
     item->lastKey = (QUERY_IS_ASC_QUERY(pQuery)? pDataBlockInfo->window.ekey:pDataBlockInfo->window.skey) + step;
   }
 
+  item->cur = tsBufGetCursor(pRuntimeEnv->pTSBuf);
+
   // todo refactor: extract method
   for(int32_t i = 0; i < pQuery->numOfOutput; ++i) {
     if (pQuery->pSelectExpr[i].base.functionId != TSDB_FUNC_ARITHM) {