On 8/17/07, Dan Falconer <lists_slony1-general at avsupport.com> wrote:
> On Wednesday 15 August 2007 16:33, David Rees wrote:
> > Why are you running such an old version of Pg? You should be running
> > 8.0.13 at least...
>
> Good point... I'm not a DBA, but I play one at my job.  ;)

:-) Get that beast upgraded to the latest maintenance release if
possible. Many have reported that going to the latest major release is
a good idea as well.

> The master server has a very worrisome load, running between 5-20.  I took a
> snapshot of it:
>         load average: 13.18, 7.23, 4.33

The load average is fairly high for a dual-processor machine, but your
vmstat output looks very benign with the system sitting at 50% idle
and low IO wait times.

> There's also a fetch that's been running for a very long time (there was a
> poorly timed vacuum of the whole database that took 2 days while this was
> running; this has been formatted for your screen)::::

What is that process doing according to postgres? What locks are being
held and are any processes being blocked by that long running query?

> The slons aren't run with any special settings.  They're started using
> the "slon_start" bash script included with Slony (some items removed to
> protect the innocent):::
>
> /usr/local/pgsql/bin/slon -s 5000 -d2 replication host=******* dbname=pl
> user=postgres port=5432

You might want to try bumping up the maximum sync group size from the
default of 6 to something like 50-100 to see if that helps.

What about postgresql tuning itself? What do the performance related
postgresql.conf settings look like?

-Dave