Actually, that solution didn't work so well. Even very small delays
in the loop caused the entire loop to perform too slowly to be useful
in the production environment. I ended up producing a small patch out
of it :P, but we ended up using pgpool to reduce connections from
another part of the app, which made the pg_autovacuum spikes less
troublesome overall.
-tfo
--
Thomas F. O'Connell
Co-Founder, Information Architect
Sitening, LLC
Strategic Open Source: Open Your i™
http://www.sitening.com/
110 30th Avenue North, Suite 6
Nashville, TN 37203-6320
615-260-0005
On May 15, 2005, at 9:26 PM, Matthew T. O'Connor wrote:
> Mindaugas Riauba wrote:
>
>
>>> The "vacuum cost" parameters can be adjusted to make vacuums fired
>>> by pg_autovacuum less of a burden. I haven't got any specific
>>> numbers
>>> to suggest, but perhaps someone else does.
>>>
>>>
>>
>> It looks like that not only vacuum causes our problems. vacuum_cost
>> seems to lower vacuum impact but we are still noticing slow
>> queries "storm".
>> We are logging queries that takes >2000ms to process.
>> And there is quiet periods and then suddenly 30+ slow queries
>> appears in
>> log within the same second. What else could cause such behaviour?
>> WAL log
>> switch? One WAL file seems to last <1 minute.
>>
>>
>
> How long are these quite periods? Do the "strom" periods
> correspond to pg_autovacuum loops? I have heard from one person
> who had LOTS of databases and tables that caused the pg_autovacuum
> to create a noticable load just updateing all its stats. The
> solution in that case was to add a small delay insidet the inner
> pg_autovacuum loop.