Re: Maintain the pathkesy for subquery from outer side information

Andy Fan <zhihui.fan1213@gmail.com> writes:
> When I am working on the UnqiueKey stuff, I find the following cases.
> SELECT * FROM (SELECT * FROM t offset 0) v ORDER BY a;
> // root->query_keys = A.  root->order_pathkeys = A
> // Current: subroot->query_pathkeys = NIL.
> // Expected:  subroot->xxxx_pathkeys = [A].

Why do you "expect" that?  I think pushing the outer ORDER BY past a
LIMIT is an unacceptable semantics change.

            regards, tom lane