| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Andrew Gierth <andrew(at)tao11(dot)riddles(dot)org(dot)uk> |
| Cc: | peter_e(at)gmx(dot)net (Peter Eisentraut), Greg Stark <gsstark(at)mit(dot)edu>, Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: Aggregate ORDER BY patch |
| Date: | 2009-11-13 17:09:16 |
| Message-ID: | 4505.1258132156@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Andrew Gierth <andrew(at)tao11(dot)riddles(dot)org(dot)uk> writes:
> "Peter" == Peter Eisentraut <peter_e(at)gmx(dot)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
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