Re: [HACKERS] Oops, I seem to have changed UNION's behavior - Mailing list pgsql-hackers

Thomas Lockhart <lockhart@alumni.caltech.edu> writes:
>>>> Am I right in thinking that UNION (without ALL) is defined to do a
>>>> DISTINCT on its result, so that duplicates are removed even if the
>>>> duplicates both came from the same source table?  That's what 6.4.2
>>>> does, but I do not know if it's strictly kosher according to the SQL
>>>> spec.

> (Just in case this is still active)

> Yes, this is the right behavior according to SQL92...

OK, then 6.5 is still broken :-(.  I know a lot more about the planner
than I did then, so I will see if I can fix it "right" --- that is,
without taking out equal()'s ability to detect equality of Query nodes.

If that seems too hard/risky, I will just lobotomize equal() instead.

Thanks for the reminder, Bruce --- I had forgotten about this issue.
        regards, tom lane