From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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 18:13:14 |
Message-ID: | 603c8f071002211013o6ff4651bq1602ab3996f1a218@mail.gmail.com |
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Lists: | pgsql-hackers |
On Sun, Feb 21, 2010 at 1:05 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> 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.
Right. Without prejudice to my earlier statements that I think this
might possibly be a good thing to do anyway, the case for it would be
a lot stronger if it provided some genuine additional functionality.
...Robert
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