Re: Speeding up aggregates

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@agliodbs.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@postgresql.org)
>

--
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073