| From: | Simon Riggs <simon(at)2ndQuadrant(dot)com> |
|---|---|
| To: | Matthew Wakeling <matthew(at)flymine(dot)org> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Dimitri <dimitrik(dot)fr(at)gmail(dot)com>, Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>, Dimitri Fontaine <dfontaine(at)hi-media(dot)com>, Alvaro Herrera <alvherre(at)commandprompt(dot)com>, Aidan Van Dyk <aidan(at)highrise(dot)ca>, Merlin Moncure <mmoncure(at)gmail(dot)com>, PostgreSQL Performance <pgsql-performance(at)postgresql(dot)org> |
| Subject: | Re: Any better plan for this query?.. |
| Date: | 2009-05-19 11:36:25 |
| Message-ID: | 1242732985.14551.188.camel@ebony.2ndQuadrant |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-performance |
On Tue, 2009-05-19 at 12:17 +0100, Matthew Wakeling wrote:
> Yes, Postgres has been missing the boat on this one for a while. +1 on
> requesting this feature.
That's an optimizer feature.
> Speaking of avoiding large sorts, I'd like to push again for partial
> sorts. This is the situation where an index provides data sorted by
> column "a", and the query requests data sorted by "a, b". Currently,
> Postgres sorts the entire data set, whereas it need only group each
> set of identical "a" and sort each by "b".
This is an executor feature.
Partially sorted data takes much less effort to sort (OK, not zero, I
grant) so this seems like a high complexity, lower value feature. I
agree it should be on the TODO, just IMHO at a lower priority than some
other features.
--
Simon Riggs www.2ndQuadrant.com
PostgreSQL Training, Services and Support
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Simon Riggs | 2009-05-19 11:41:00 | Re: Any better plan for this query?.. |
| Previous Message | Matthew Wakeling | 2009-05-19 11:17:47 | Re: Any better plan for this query?.. |