I wrote:
> However ... I don't like this implementation, not even a little
> bit.
I forgot to mention a third problem, which is that reassigning the
alias during subquery pullup means it doesn't happen if subquery
pullup doesn't happen. As an example, with your patch:
regression=# explain verbose select * from (values (1), (2)) v(x);
QUERY PLAN
----------------------------------------------------
Values Scan on v (cost=0.00..0.03 rows=2 width=4)
Output: v.x
(2 rows)
regression=# explain verbose select * from (values (1), (random())) v(x);
QUERY PLAN
-------------------------------------------------------------
Values Scan on "*VALUES*" (cost=0.00..0.03 rows=2 width=8)
Output: "*VALUES*".column1
(2 rows)
That's because the volatile function prevents subquery flattening.
regards, tom lane
