Re: Re: slow server

My result speeds are from running a simple loop on my web server in a php script
via a pg_pconnect connection. I run the loop 1000 times and get the time taken
to perform the whole loop and then divy the time by 1000 to get the average time
per query. (The Celeron can finish with 1000 in 1/3 the time the PIII takes to
perform 10)

On the PIII I didn't try over 100, lest it take forever...

I also double checked in psql for each system and there is a definite ~1 second
pause on the PIII that does not exist on the Celeron.

The startup parameters are the same for both systems: -i -B 256 -N 128

Also, I checked 'top' when the query loop is running and postgres is using 99.x
% of CPU.

Marc Wrubleski

Mitch Vincent wrote:

> In addition to my previous questions and all other questions, I have another
> :-)
>
> Where are you getting your .002 and .75 numbers? Perhaps it's the way in
> which you're measuring the queries that has the problem? Oh and what OS are
> you using?
>
> -Mitch
> Software development :
> You can have it cheap, fast or working. Choose two.
>
> ----- Original Message -----
> From: "Richard Huxton" <dev@archonet.com>
> To: "Marc Wrubleski" <mlwruble@sorexsoftware.com>;
> <pgsql-general@postgresql.org>
> Sent: Tuesday, April 03, 2001 4:41 PM
> Subject: Re: slow server
>
> > From: "Marc Wrubleski" <mlwruble@sorexsoftware.com>
> >
> > > Hi, I have two systems one is a 500Mhz Celeron with 128 MB ram and IDE
> > > Disks, the other is 800Mhz PIII, 512MB RAM, SCSI Disks.
> > >
> > > Obviously the PIII should stomp on the performance of the Celeron, but
> > > my postgres installation on the faster system is MUCH slower.
> > >
> > > I simple query on two tables joined on the celeron takes about .002
> > > seconds. On the PIII it takes .75 seconds. Same Query, same tables, same
> > > indexes. The results from explain are the same. the results from the
> > > query are the same.
> >
> > 0.002 seconds? Doubtful, but even if it was 0.2 seconds the results are
> > puzzling. There's someone else with a suspiciously similar question
> recently
> > too (Daniel Akerud - but with a circle over the A)
> >
> > > Any Ideas?
> > >
> > > One thing to think about is the PIII was installed via RPM and the
> > > Celeron wass compiled on that machine. Could this be the limiting
> > > factor?
> >
> > Well - RPMs tend to be i386 optimised rather than for Pentiums (ie they're
> > not), but that'd be all. I take it you're not seeing any disk activity
> > during this query, which would mean it *must* be CPU related.
> >
> > Could you post the version of Postgres you have on each machine, along
> with
> > the explain for the query? It might mean something to one of the
> developers.
> > Oh - OS with versions would be useful too (Linux presumably, but versions
> > might be useful).
> >
> > FWIW there are only two things I can think of:
> >
> > 1. Cache issues - maybe the RPM is breaking the caching on the PIII
> > 2. Broken socket code - although I can't think what would do this
> > 3. The RPM and compiled versions are different and something odd has
> > changed.
> >
> > If nothing else on the machine seems slow, I can only suggest compiling
> from
> > source and seeing what that does for you.
> >
> > - Richard Huxton
> >
> >
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