Hi,
this is a stock PGDG 9.6:
postgres=# with i(x) as (values (1::int)), j(y) as (values (2::int)) select x from (select x from i union all select y from j) b;
x
---
1
2
(2 rows)
postgres=# with i(x) as (values (1::int)), j(y) as (values (2::int)) select max(x) from (select x from i union all select y from j) b;
ERROR: could not find plan for CTE "i"
The same on 9.5:
postgres=# with i(x) as (values (1::int)), j(y) as (values (2::int)) select x from (select x from i union all select y from j) b;
x
---
1
2
(2 rows)
postgres=# with i(x) as (values (1::int)), j(y) as (values (2::int)) select max(x) from (select x from i union all select y from j) b;
max
-----
2
(1 row)
Is this a bug or is my assumption that this should work wrong?
Both the aggregate and the UNION are required to trigger the bug:
postgres=# with i(x) as (values (1::int)) select x from (select x from i union all select 3::int) b;
x
---
1
3
(2 rows)
postgres=# with i(x) as (values (1::int)) select max(x) from (select x from i) b;
max
-----
1
(1 row)
postgres=# with i(x) as (values (1::int)) select max(x) from (select x from i union all select 3::int) b;
ERROR: could not find plan for CTE "i"
Thanks,
Torsten