| From: | Greg Stark <gsstark(at)mit(dot)edu> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Mark Kirkwood <markir(at)paradise(dot)net(dot)nz>, Tobias Brox <tobias(at)nordicbet(dot)com>, pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: Limit + group + join |
| Date: | 2005-08-27 03:03:30 |
| Message-ID: | 87mzn484jh.fsf@stark.xeocode.com |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-performance |
Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> writes:
> As far as the "desc" point goes, the problem is that mergejoins aren't
> capable of dealing with backward sort order, so a merge plan isn't
> considered for that case (or at least, it would have to have a sort
> after it, which pretty much defeats the point for a fast-start plan).
> I have some ideas about fixing this but it won't happen before 8.2.
Of course in this case assuming "id" is an integer column you can just sort by
-id instead.
--
greg
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Bruno Wolff III | 2005-08-27 06:19:49 | Re: Need indexes on empty tables for good performance ? |
| Previous Message | Mark Kirkwood | 2005-08-27 02:55:22 | Re: Limit + group + join |