Problem:
When create view with projection group_concat(xxx, xxx order by orderkey). It will failed during second parse of inline view
For example:
it works when doing
"SELECT id, group_concat(`name`, "," ORDER BY id) AS test_group_column FROM test GROUP BY id"
but when create view it does not work
"create view test_view as SELECT id, group_concat(`name`, "," ORDER BY id) AS test_group_column FROM test GROUP BY id"
Reason:
when creating view, we will doing parse again of view.toSql() to check whether it has some syntax error. And when doing toSql() to group_concat with order by, it add seperate ', ' between second parameter and order by. So when parsing again, it
would failed because it is different semantic with original statement.
group_concat(`name`, "," ORDER BY id) ==> group_concat(`name`, "," , ORDER BY id)
Solved:
Change toSql of group_concat and add order by statement analyze() of group_concat in Planner cause it would work if we get order by from view statement and do not analyze and binding slot reference to it
Problem:
when use select group_concat(distinct a, 'seg1'), group_concat(distinct b, 'seg2') ... Error would rised
Reason:
Group_concat function regard 'seg' as arguments also, so multi distinct column error would rised
Solved:
let Multi Distinct group_concat function only get first argument as real argument
1. signatures without order element are wrong
2. signature with one arg is miss
3. group_concat should be NullableAggregateFunction
4. fold constant on fe should not fold NullableAggregateFunction with null arg
TODO
1. reorder rewrite rules, and then only forbid fold constant on NullableAggregateFunction with alwaysNullable == true
