The child.open() function is not called before this commit.
If the assert num rows node has child which process data in open function, the assert num rows node will fetch no data from child. So the result will be empty(incorrect).
This error only appear in inner subquery which has a aggregation function.
For example:
`select * from table where k1=(select k1 from (select avg(k1) from table) a);`
The first level of subquery returns a non-scalar value, so the assert num rows node is needed.
The second level of subquery has a aggregation function, so the child of assert node is aggregate node.
However, if the open stage of the aggregate node is not called, the get next state of aggregate node will return empty set.
So the result is wrong.
Fixed#3435.
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
