Re: Performance problem. Could it be related to 8.3-beta4?

2008/1/5, Greg Smith <gsmith(at)gregsmith(dot)com>:
> On Fri, 4 Jan 2008, Clodoaldo wrote:
>
> > I built a new system and installed 8.3-beta4.
>
> How did you get 8.3-beta4?

I built from the source rpm, which i installed in my machine. There is
something I forgot to mention. I created a patch to change
XLOG_SEG_SIZE and built with it:
-#define XLOG_SEG_SIZE (16*1024*1024)
+#define XLOG_SEG_SIZE (1024*1024*1024)

I can expect it to make no difference but could it change the
performance to worse? And with that big gap?

> If you used the RPMs available from the
> PostgreSQL FTP site, those are optimized for finding bugs at the expense
> of speed. If that's where you got them from, try putting this line in
> your postgresql.conf and testing 8.3 again:
>
> debug_assertions = false

I tried with it restarting the server and it makes no significant difference.

> > Production system:
> > #autovacuum = off # enable autovacuum subprocess?
> >
> > New system's postgresql.conf:
>
> I didn't see anything about autovacum on the new system. If it's off on
> 8.2 and on in 8.3 (the default) that might be contributing to your
> difference.

Missed that. New system:
autovacuum = off # 'on' requires track_counts

> Also, I hope you don't normally run your production system with fsync=off
> as that's kind of scary.

I do. That is a hobby site and I have a good UPS. In four years I
hadn't a problem with crashes. If it happens I will just reload from
the daily backup.

Regards, Clodoaldo Pinto Neto