On Wed, Jan 07, 2004 at 02:31:22 -0500,
Tom Lane <tgl@sss.pgh.pa.us> wrote:
>
> I just a couple days ago added some logic to CVS tip to notice that the
> sub-select has a DISTINCT clause, and not add unnecessary unique-ifying
> processing on top of it. So in 7.5, writing a DISTINCT clause will
> amount to forcing a particular query plan, which might or might not be
> the best thing but hopefully won't be too terrible. But in 7.4 it has
> nothing to recommend it ...
Can't the DISTINCT be dropped if there isn't a LIMIT clause?
Similarly UNION, INTERSECTION and EXCEPT could also also be changed
to the ALL forms if there isn't a LIMIT.