| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Robert Haas <robertmhaas(at)gmail(dot)com> |
| Cc: | Lucas <lucas75(at)gmail(dot)com>, Andrew Dunstan <andrew(at)dunslane(dot)net>, Dimitri Fontaine <dfontaine(at)hi-media(dot)com>, Dave Page <dpage(at)pgadmin(dot)org>, Jaime Casanova <jcasanov(at)systemguards(dot)com(dot)ec>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: scheduler in core |
| Date: | 2010-02-21 18:05:16 |
| Message-ID: | 25985.1266775516@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> On Sun, Feb 21, 2010 at 10:17 AM, Lucas <lucas75(at)gmail(dot)com> wrote:
>> I wonder if the scheduler already existed before the
>> implementation of the autovacuum, its implementation would
>> not be a function executed by the in-core scheduler?
> The real genius of autovacuum is that it works out when there has been
> enough activity in particular tables that they need to be vacuumed.
> We might be able to use an in-core scheduler to wake it up every
> minute to look at the stats, or whatever it is that we do, but that's
> not all that exciting.
The wake-up-every-N-seconds part of it is actually the weakest part
(search the archives for questions about autovacuum_naptime). To my
mind, the killer reason why autovac needed to be integrated is so that
the system itself could trigger autovac runs in response to threatened
XID wraparound conditions. A facility for scheduling user jobs, almost
by definition, won't have any system-internal trigger conditions.
regards, tom lane
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