Re: ...WHERE TRUE" condition in union results in bad query pla

Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> On Sat, Mar 3, 2012 at 10:03 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> Sooner or later I'd like to relax the restriction that appendrel members
>> can't have extra WHERE clauses, but don't hold your breath waiting...

> Does this comment need updating?

> * Note: the data structure assumes that append-rel members are single
> * baserels. This is OK for inheritance, but it prevents us from pulling
> * up a UNION ALL member subquery if it contains a join. While that could
> * be fixed with a more complex data structure, at present there's not much
> * point because no improvement in the plan could result.

No, that's a different restriction.

regards, tom lane