Re: Sort

----- Original Message -----
From: "Nathan Barnett" <nbarnett(at)cellularphones(dot)com>
To: "'Mitch Vincent'" <mitch(at)venux(dot)net>
Sent: Friday, July 21, 2000 3:03 PM
Subject: RE: [GENERAL] Sort

> Here is the query:
>
> SELECT Impression.AdNumber_AdNum,
> Impression.Webmaster_WebmasterNum,
> Impression.Banner_BannerNum, COUNT(Click.ClickNum)
> AS ClickCount
> FROM Impression INNER JOIN
> Click ON
> Impression.ImpressionNum = Click.Impression_ImpressionNum
> GROUP BY Impression.AdNumber_AdNum,
> Impression.Webmaster_WebmasterNum,
> Impression.Banner_BannerNum
>
> -----------------
> Nathan Barnett
>
> -----Original Message-----
> From: pgsql-general-owner(at)hub(dot)org [mailto:pgsql-general-owner(at)hub(dot)org]On
> Behalf Of Mitch Vincent
> Sent: Friday, July 21, 2000 2:48 PM
> To: Nathan Barnett; pgsql-general(at)postgresql(dot)org
> Subject: Re: [GENERAL] Sort
>
>
> Show the query and maybe someone could help :-)
>
> ----- Original Message -----
> From: "Nathan Barnett" <nbarnett(at)cellularphones(dot)com>
> To: <pgsql-general(at)postgresql(dot)org>
> Sent: Friday, July 21, 2000 2:33 PM
> Subject: [GENERAL] Sort
>
>
> > I'm currently using v7.0.2 of PostgreSQL.
> >
> > I have a query that performs a group by on three columns. The EXPLAIN
of
> > the query is as follows:
> >
> > Aggregate (cost=4116.05..4125.47 rows=94 width=24)
> > -> Group (cost=4116.05..4123.12 rows=942 width=24)
> > -> Sort (cost=4116.05..4116.05 rows=942 width=24)
> > -> Nested Loop (cost=0.00..4069.52 rows=942 width=24)
> > -> Seq Scan on click (cost=0.00..15.42 rows=942
> > width=8)
> > -> Index Scan using impression_pkey on impression
> > (cost=0.00..4.29 rows=1 width=16)
> >
> > I need to speed up this query. I have already created an index on the
> three
> > columns query_idx(columna, columnb,columnc). Is there some other index
> that
> > I could add which would speed up the query. There is a high frequency
in
> > the table of each group. Each group probably makes up 10% of the table.
> > Does this force a sequence scan when sorting and grouping? Basically
just
> > looking for suggestions.
> >
> >
> > ----------------
> > Nathan Barnett
> >
> >
>
>
>