Re: way to speed up a SELECT DISTINCT? - Mailing list pgsql-performance

From Peter Childs
Subject Re: way to speed up a SELECT DISTINCT?
Date
Msg-id Pine.LNX.4.44.0310101211270.5720-100000@RedDragon.Childs
Whole thread Raw
In response to Re: way to speed up a SELECT DISTINCT?  (Seth Ladd <seth@picklematrix.net>)
List pgsql-performance
On Fri, 10 Oct 2003, Seth Ladd wrote:

> >> Is there any way to speed this up, or is that DISTINCT going to keep
> >> hounding me?
> >>
> >> I checked the mailing list, and didn't see anything like this.
> >>
> >> Any tips or hints would be greatly appreciated.  Thanks for your help!
> >> Seth
> >>
> >>
> >     Try group by instead. I think this is an old bug its fixed in
> > 7.3.2 which I'm using.
> >
> > Peter Childs
> > `
> >
> >
> > peter@bernardo:express=# explain select distinct region from region;
> >                                           QUERY PLAN
> > -----------------------------------------------------------------------
> > -----------------------
> >  Unique  (cost=0.00..4326.95 rows=9518 width=14)
> >    ->  Index Scan using regionview_region on region
> > (cost=0.00..4089.00
> > rows=95183 width=14)
> > (2 rows)
>
> Thanks for the tip, I'll give this a shot soon.  I am curious, your
> example above does not use GROUP BY yet you have an INDEX SCAN.  I am
> using a similar query, yet I get a full table scan.  I wonder how they
> are different?
>
> I'll try the group by anyway.
>
    Its a guess but ANALYSE might help. `

Peter Childs


pgsql-performance by date:

Previous
From: Christopher Kings-Lynne
Date:
Subject: Re: way to speed up a SELECT DISTINCT?
Next
From: Jeff
Date:
Subject: Re: backup/restore - another area.