From: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> |
---|---|
To: | Hannu Krosing <hannu(at)tm(dot)ee> |
Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Josh Berkus <josh(at)agliodbs(dot)com>, pgsql-performance(at)postgresql(dot)org |
Subject: | Re: Speeding up aggregates |
Date: | 2002-12-09 18:09:31 |
Message-ID: | 200212091809.gB9I9VK05778@candle.pha.pa.us |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-performance |
Added.
---------------------------------------------------------------------------
Hannu Krosing wrote:
> Hannu Krosing kirjutas L, 07.12.2002 kell 02:32:
> > Tom Lane kirjutas L, 07.12.2002 kell 01:46:
> > > "Josh Berkus" <josh(at)agliodbs(dot)com> writes:
> > > > What have other Postgres users done to speed up aggregates on large
> > > > tables?
> > >
> > > FWIW, I've implemented hashed aggregation in CVS tip.
> >
> > Great!
> >
> > This should also make it easier to implement all kinds of GROUP BY
> > ROLLUP|CUBE|GROUPING SETS|() queries.
>
> Of these only ROLLUP can be done in one scan after sort, all others
> would generally require several scans without hashing.
>
>
> I just noticed that we don't even have a TODO for this. I think this
> would be a good TODO item.
>
> Bruce, could you add:
>
> * Add ROLLUP, CUBE, GROUPING SETS options to GROUP BY
>
>
> They are all defined in SQL99 p.79 <group by clause>
>
>
> Some more background info (from a quick Google search)
>
> a very short overview:
> http://www.neddo.com/dm3e/sql3&olap.html
>
>
> more thorough guide for DB2:
> http://www.student.math.uwaterloo.ca/~cs448/db2_doc/html/db2s0/frame3.htm#db2s0279
>
>
> -----------------
> Hannu
>
>
> ---------------------------(end of broadcast)---------------------------
> TIP 2: you can get off all lists at once with the unregister command
> (send "unregister YourEmailAddressHere" to majordomo(at)postgresql(dot)org)
>
--
Bruce Momjian | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 359-1001
+ If your life is a hard drive, | 13 Roberts Road
+ Christ can be your backup. | Newtown Square, Pennsylvania 19073
From | Date | Subject | |
---|---|---|---|
Next Message | Josh Berkus | 2002-12-09 19:53:03 | Re: questions about disk configurations |
Previous Message | Hubert depesz Lubaczewski | 2002-12-09 13:05:21 | Re: questions about disk configurations |