Andy Fan <zhihui(dot)fan1213(at)gmail(dot)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