Hernan Saltiel wrote:
> 
> How can I meassure how much is too much use of my hardware when Slony is 
> in place?
> I can meassure the CPU, memory, disk IO, and network use, but how much 
> is needed in order to let Slony work well?
> Is there any way to calculate this on a transaction number and size basis?
> Thanks!

The other thing you should look into is if your having performance 
issues on your database from improper/insufficient vacuuming.  Back in 
the 8.0 days vacuuming issues where pretty common (I think 8.0 was 
before auto-vacuum or at least before auto-vacuum got good).

Are your application tables bloated?
Are your slony tables bloated?
Are your vacuum processes taking a long time?
If your've had vacuum issues in the past have you exceeded the size 
you've allocated to the free-space map.

Vacuuming the entire database through a single "VACUUM" command launched 
from cron is somtimes not the best approach, sometimes you need to issue 
individual vacuum commands on a per table basis where some tables get 
hit frequently (maybe a few times an hour) while others might only get 
vacuumed once a week.   It all depends on the acccess patterns to the 
tables and with older versions of postgresql the DBA is often left to 
figure this out on their own.

Also slony should be issuing vacuum commands against the slony tables so 
you probably don't want 'other' vacuum commands that regularly get run 
to duplicate the work.





>  
> 
> 
>      > Can someone point me where should i look into and how to improve
>     replication
>      > performance.
> 
>     More / faster drives and controllers.
> 
>      > As of now there is no chance for upgradation of version.
> 
>     That would be the first thing I'd recommend.  Since you can't do it,
>     you're gonna have to have faster hardware, specifically the IO
>     subsystem.
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> 
> 
> 
> -- 
> HeCSa
> 
> 
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-- 
Steve Singer
Afilias Canada
Data Services Developer
416-673-1142