Thread: extremely slow when execute select/delete for certain tables only...

I'm facing a very weird problem.
Recently our database run very slow when execute Delete/Select statement
for a few tables only..
The largest table only have 50K rows of data.

When I run the statement from pgAdmin although it is slow but not as slow
as run from webapp.
When I run the statement from webapp, it become extremely slow.
Even a simple delete statement will takes 20-40 minutes to complete.

I already vacuum those tables with full option but it still the same.

What could be the possible causes of this problem?
How can I solve it?

CPU - Intel Xeon 2.40 GHz
Memory - 1.5G
Postgresql version: 7.2.2

Thanks.

Hi, Kah,

kah_hang_ang@toray.com.my wrote:

> I already vacuum those tables with full option but it still the same.
>
> What could be the possible causes of this problem?
> How can I solve it?
>
> CPU - Intel Xeon 2.40 GHz
> Memory - 1.5G
> Postgresql version: 7.2.2

First, you should consider to upgrade your PostgreSQL server to a newer
version, at least to 7.2.8 which fixes some critical bugs.

But it will be much better to upgrade to current 8.1 version, as I think
that your problem is caused by index bloat, and indices are handled much
better in 8.1.

Try recreating your indices using REINDEX command.

HTH,
Markus



--
Markus Schaber | Logical Tracking&Tracing International AG
Dipl. Inf.     | Software Development GIS

Fight against software patents in EU! www.ffii.org www.nosoftwarepatents.org

On Mon, May 08, 2006 at 11:21:16AM +0200, Markus Schaber wrote:
> Hi, Kah,
>
> kah_hang_ang@toray.com.my wrote:
>
> > I already vacuum those tables with full option but it still the same.
> >
> > What could be the possible causes of this problem?
> > How can I solve it?
> >
> > CPU - Intel Xeon 2.40 GHz
> > Memory - 1.5G
> > Postgresql version: 7.2.2
>
> First, you should consider to upgrade your PostgreSQL server to a newer
> version, at least to 7.2.8 which fixes some critical bugs.

Note that 7.2.x isn't supported anymore, and there's data loss bugs that
could affect it. You should at least move up to 7.4.x.

> But it will be much better to upgrade to current 8.1 version, as I think
> that your problem is caused by index bloat, and indices are handled much
> better in 8.1.
>
> Try recreating your indices using REINDEX command.

And if that doesn't work we need at least the output of EXPLAIN, if not
EXPLAIN ANALYZE.
--
Jim C. Nasby, Sr. Engineering Consultant      jnasby@pervasive.com
Pervasive Software      http://pervasive.com    work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf       cell: 512-569-9461