This commit add a new plan node named AssertNumRowsNode
which is used to determine whether the number of rows exceeds the limit.
The subquery in Binary predicate and Between-and predicate should be added a AssertNumRowsNode
which is used to determine whether the number of rows in subquery is more than 1.
If the number of rows in subquery is more than 1, the query will be cancelled.
For example:
There are 4 rows in table t1.
Query: select c1 from t1 where c1=(select c2 from t1);
Result: ERROR 1064 (HY000): Expected no more than 1 to be returned by expression select c2 from t1
ISSUE-2270
TPC-DS 6,54,58
The new msg of limit exceed: "Memory exceed limit. %msg, Backend:%ip, fragment:%id Used:% , Limit:%. xxx".
This commit unifies the msg of 'Memory exceed limit' such as check_query_state, RETURN_IF_LIMIT_EXCEEDED and LIMIT_EXCEEDED.
Help to locate big query when system overload, by checking consumptions of running parts of current all queries or specified one query. Its basic mode of work is as follows: firstly trigger BE to report RuntimeProfiles, and wait a moment. secondly caculate consumptions with RuntimeProfiles reported by BE. The consumptions supported by it are the cost of running ExecNode in query when call it.
