On Fri, 2006-03-24 at 16:20 -0500, Tom Lane wrote:
> Rod Taylor <pg(at)rbt(dot)ca> writes:
> > The reason for the subselect is to prevent multiple calculations of
> > individual column aggregates. I believe it *may* be calculated multiple
> > times otherwise this would work just as well:
>
> > select case when max(a) > max(b) then max(a) else max(b) end as max from
> > tab;
>
> Just for the record, we've gotten that right since 7.4. greatest()
> would be a notationally cleaner solution than CASE, but multiple
> occurrences of identical aggregates don't cost much of anything.
Thanks. I could not remember one way or the other.
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