From: Rod Taylor <pg@rbt.ca>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Amos Hayes <ahayes@polkaroo.net>
Cc: pgsql-sql@postgresql.org
Subject: Re: Find min and max values across two columns?
Date: Fri, 24 Mar 2006 16:20:06 -0500
Message-ID: <1143235206.90799.108.camel@home> (raw)
In-Reply-To: <10495.1143235231@sss.pgh.pa.us>
References: <DAD4674C-1896-4F24-B43B-B884491DB931@polkaroo.net>
<1143233215.90799.91.camel@home>
<10495.1143235231@sss.pgh.pa.us>
On Fri, 2006-03-24 at 16:20 -0500, Tom Lane wrote:
> Rod Taylor <pg@rbt.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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To: pgsql-sql@postgresql.org
Cc: pg@rbt.ca, tgl@sss.pgh.pa.us, ahayes@polkaroo.net
Subject: Re: Find min and max values across two columns?
In-Reply-To: <1143235206.90799.108.camel@home>
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