Re: Strange behaviour under heavy load

New information.

When I run CHECKPOINT manually in psql console, effect is fully reproduced.
So - it is a checkpoint slowdown.

The quesion is - how to make CHECKPOINT work faster?

On 3/27/07, Dmitry Koterov <dmitry(at)koterov(dot)ru> wrote:
>
> How to tune them?
>
> Now I have:
>
> checkpoint_segments = 5 # in logfile segments, min 1, 16MB each
> checkpoint_timeout = 900 # range 30-3600, in seconds
> checkpoint_warning = 30 # in seconds, 0 is off
>
> No checkpoint warnings in pgsql logs.
>
>
> On 3/27/07, Oleg Bartunov <oleg(at)sai(dot)msu(dot)su> wrote:
> >
> > hmm,
> >
> > looks like checkpoint ?
> > Check checkpoint settings in postgresql.conf.
> >
> >
> > Oleg
> > On Tue, 27 Mar 2007, Dmitry Koterov wrote:
> >
> > > Hello.
> > >
> > > I have found that sometimes heavy loaded PostgreSQL begins to run all
> > the
> > > queries slower than usual, sometimes - 5 and more times slower. I
> > cannot
> > > reprocude that, but symptoms are the following: queries work very fast
> > for
> > > 5-10 minutes, and after that - significant slowdown (every query, even
> > a
> > > simple one, works 5-10 and ever more times slower), disk write
> > activity
> > > grows too (but not everytime - I don't know exactli if there is a
> > direct
> > > correlation). 2-3 seconds, then - performance restores back to normal.
> >
> > >
> > > Autovacuum is turned off.
> > >
> > > Machine has 2 processors, huge memory, fast SCSI disks.
> > >
> > > I understand that there is too less information. Please advice what to
> > > monitor for better problem discovering.
> > >
> >
> > Regards,
> > Oleg
> > _____________________________________________________________
> > Oleg Bartunov, Research Scientist, Head of AstroNet (www.astronet.ru ),
> > Sternberg Astronomical Institute, Moscow University, Russia
> > Internet: oleg(at)sai(dot)msu(dot)su, http://www.sai.msu.su/~megera/<http://www.sai.msu.su/%7Emegera/>
> > phone: +007(495)939-16-83, +007(495)939-23-83
> >
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>