"Colin 't Hart" <[email protected]> writes:
> On 11 November 2013 14:34, Tom Lane <[email protected]> wrote:
>> No, and it probably won't ever be, since the semantics aren't the same.
>> EXCEPT/INTERSECT imply duplicate elimination.
> Can't we just use DISTINCT for that?
If you have to do a DISTINCT it's not clear to me that you're going to get
much win.
(The bigger picture here is that pretty much zero optimization effort has
been spent on EXCEPT/INTERSECT, because they're just not used that much
compared to other places where we could put that effort.)
regards, tom lane
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