D'Arcy J.M. Cain wrote:
> I have an idea for a change to the contributed module pg_autovacuum that
> I would like to run by people. What I want to do is make sure that when
> vacuum (or analyze) runs that it takes no time from actual transactions.
> To this end I want to add an option (-n?) which runs nice(2) on the
> process ID of the backend.
> I realize that there will be a limitation that this can only work when
> pg_autovacuum is running on the same host as the server. I plan to
> handle that by ignoring the new option if the -h option (or equivalent
> environment variable) is also set.
> The big question I have is this. Is this strategy likely to improve my
> transaction processing?
There is a much better way available in PostgreSQL 8.0 to reduce the impact
of VACUUM: cost-based vacuum delay.
There are five GUC-variables that control vacuum delay. The most important
is vacuum_cost_delay(int), because it actually enables (value >0) or
disables (value =0) the feature.
This can be set during runtime via SET. The default value for
vacuum_cost_delay is currently 0.
So what you could do, is make a new option in pg_autovacuum that will set
vacuum_cost_delay before executing vacuum. So one can leave
vacuum_cost_delay at zero in postgresql.conf, but enable it for background
vacuum in pg_autovacuum.
In response to
pgsql-hackers by date
|Next:||From: Greg Stark||Date: 2004-10-22 16:54:58|
|Subject: Re: code question: storing INTO relation|
|Previous:||From: Tom Lane||Date: 2004-10-22 16:06:20|
|Subject: Re: Nice vacuums |