Re: Speeding up aggregates

Added.

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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
>
>
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