Re: slow server

From: "Marc Wrubleski" <mlwruble(at)sorexsoftware(dot)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