Re: Aggregate ORDER BY patch
Tom Lane <tgl@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>
To: Andrew Gierth <andrew@tao11.riddles.org.uk>
Cc: peter_e@gmx.net (Peter Eisentraut), Greg Stark <gsstark@mit.edu>, Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>, pgsql-hackers@postgresql.org
Date: 2009-11-13T17:09:16Z
Lists: pgsql-hackers
Andrew Gierth <andrew@tao11.riddles.org.uk> writes: > "Peter" == Peter Eisentraut <peter_e@gmx.net> writes: > Peter> This is exactly the syntax that is in the spec AFAICT. > Right. The spec defines this syntax for array_agg and xmlagg (only). Cool, I had forgotten that they added that in the latest revisions. I withdraw the complaint that this patch goes too far beyond the spec. > But it would be entirely unreasonable, the way postgres works, to > implement ORDER BY for only specific aggregates. Quite. This is another instance of the thing I complained of before, that the SQL committee likes to define the behavior of specific aggregates instead of inducing a generic aggregate-behavior definition. So we're on our own to extract one, and this proposal seems pretty reasonable to me: it's useful and it's consistent with the query-level behavior of DISTINCT and ORDER BY. regards, tom lane