Re: 8.1beta3 performance

On Mon, 31 Oct 2005 17:16:46 -0600
"PostgreSQL" <martin(at)portant(dot)com> wrote:

> We're running 8.1beta3 on one server and are having ridiculous
> performance issues. This is a 2 cpu Opteron box and both processors
> are staying at 98 or 99% utilization processing not-that-complex
> queries. Prior to the upgrade, our I/O wait time was about 60% and
> cpu utilization rarely got very high, now I/O wait time is at or near
> zero.
>
> I'm planning to go back to 8.0 tonight or tomorrow night but thought
> I'd check the pqsql-performance prophets before I gave it up.

I have a stock FreeBSD 5.4 box that I put 8.1 on last night. I ran
pgbench against it and my tps dropped from ~300tps in 8.0.3 to 20tps
in 8.1. That's right. 20. No changes in any system configuration. No
data in the new 8.1 database, only the pgbench init'ed stuff. 25
clients, 100 and 1000 transactions with a scaling factor of 10, which
gives me 1,000,000 tuples to shoot through.

I wiped out the 8.1 installation, put 8.0.4 in it's place, and
pgbenched it again. ~300tps again.

It's not a problem with system configuration if 8.0 works fine, but 8.1
has problems, unless there is something that 8.1 needs tweaked that 8.0
doesn't. In that case, I just need to know what that is and I can tweak
it.

Dual Xeon 2.6GB HTT PowerEdge, 4GB RAM, RAID 5
FreeBSD 5.4 RELEASE, custom-compiled kernel
CFLAGS=-O3 -funroll-loops -pipe (also tried -O2, same difference)

Jon Brisbin
Webmeister
NPC International, Inc.