Actually, it's inconsistent with the exact same command. I've now replicated the problem by doing the following command:
select count (*) from table;
The table in question has 88899 rows.
The response time is anywhere from 1 second to 12 seconds. Different response times can occur in the same minute of testing!
Regards,
Joseph
At 02:34 PM 9/15/2003 -0700, you wrote:
On Mon, 15 Sep 2003, Joseph Bove wrote:
> I am working with a decent sized database on an extremely powerful machine. > The specs follow: > > OS: RedHat Linux 9.0 > PG Version 7.3 > Memory 1 gig > CPU Quad Processor - Unsure of exact CPUs > Hard Drive 80 gigs > Database Size 2 gigs > > > As you can see the server is built for overkill. > > The problem that I see is as follows. > > I do a rather simple query: select count (*) from large-table where column > = some value; > > About 80% of the time, the response time is sub-second. However, at 10% of > the time, the response time is 5 - 10 seconds.
Is it consistant for various values of "some value"? If so, it's possible that it's switching plans based on the apparent selectivity of the column for that value.
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