Re: why does count take so long?

On Sun, Sep 07, 2003 at 21:06:26 -0400,
Joseph Shraibman <jks(at)selectacast(dot)net> wrote:
> On a 7.3.4 database:
>
> explain analyse select count(*) from elog;
>
>
> Aggregate (cost=223764.05..223764.05 rows=1 width=0) (actual
> time=81372.11..81372.11 rows=1 loops=1)
> -> Seq Scan on elog (cost=0.00..203012.24 rows=8300724 width=0)
> (actual time=3.91..71542.53 rows=8313762 loops=1)
> Total runtime: 81378.42 msec
> (3 rows)
>
>
> It looks like the aggregate took 10 secs all by itself. What's taking
> so long?

It looks like there are 8 million log records that need to be counted.

There have been some discussions over the last few days about tricks to
get better performance if you need to use count on large tables.