Re: Improving count(*)

From: "Zeugswetter Andreas DCP SD" <ZeugswetterA(at)spardat(dot)at>
To: "Tino Wildenhain" <tino(at)wildenhain(dot)de>
Cc: "Martijn van Oosterhout" <kleptog(at)svana(dot)org>, "Rod Taylor" <pg(at)rbt(dot)ca>, "Simon Riggs" <simon(at)2ndquadrant(dot)com>, <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Improving count(*)
Date: 2005-11-18 10:45:33
Message-ID: E1539E0ED7043848906A8FF995BDA5799A53CF@m0143.s-mxs.net
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> > Since that costs, I guess I would make it optional and combine it
with
> > materialized views that are automatically used at runtime, and can
at
> > the same time answer other aggregates or aggregates for groups.
> > create materialized view xx_agg enable query rewrite as select
> > count(*), sum (col1) from xx [group by col2];
> >
>
> I wonder how many times you really need a count(*) w/o where clause.
> If I understand you correctly you are trying to optimize just this one
case?

I guess you have not read to the end. A materialized view with a group
by
as indicated in the example is able to answer all sorts of queries
with or without where clauses ( e.g. ... where col2 = 'x').

Andreas

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