| Lists: | pgsql-hackers |
|---|
| From: | Andrew Gierth <andrew(at)tao11(dot)riddles(dot)org(dot)uk> |
|---|---|
| To: | pgsql-hackers(at)postgresql(dot)org |
| Subject: | taking a stab at agg(foo ORDER BY bar) |
| Date: | 2009-10-04 08:51:05 |
| Message-ID: | 87hbuftudi.fsf@news-spur.riddles.org.uk |
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| Lists: | pgsql-hackers |
The spec defines array_agg(foo ORDER BY ...) which we don't implement
yet; obviously, we have no reason not to define this for any
aggregate, rather than just array_agg.
This doesn't seem to present any problems as far as the syntax goes,
and the actual execution is just a small matter of coding, but I'm not
seeing the best way to handle it in parse-analysis. All the existing
infrastructure for ORDER BY seems to be dependent on targetlists, which
obviously we don't have in the context of an aggregate call.
Ideas?
--
Andrew (irc:RhodiumToad)
| 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: | pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: taking a stab at agg(foo ORDER BY bar) |
| Date: | 2009-10-04 15:10:10 |
| Message-ID: | 8950.1254669010@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Andrew Gierth <andrew(at)tao11(dot)riddles(dot)org(dot)uk> writes:
> This doesn't seem to present any problems as far as the syntax goes,
> and the actual execution is just a small matter of coding, but I'm not
> seeing the best way to handle it in parse-analysis. All the existing
> infrastructure for ORDER BY seems to be dependent on targetlists, which
> obviously we don't have in the context of an aggregate call.
Well, if you don't want to refactor that code, it wouldn't be difficult
to make a one-entry tlist containing the aggregate argument, and then
throw it away again after you'd extracted what you need.
regards, tom lane