Clarification Needed: When does autovacuum daemon run?

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Hello,
=20
Postgresql-8.2 manual has mentioned following points.
* The autovacuum daemon, when enabled, runs every autovacuum_naptime
seconds.
* autovacuum_naptime (integer): Specifies the delay between "activity
rounds" for the autovacuum daemon....The delay is measured in seconds,
and the default is one minute (1m)....
=20
My Query: I want to run autovacuum daemon everyday at 5 am. By setting
autovacuum_naptime to 24*60*60 (# of seconds in a day), I can run the
daemon everyday. But, how do I ensure the daemon runs at 5am? What is
the "activity rounds" mentioned in the manual? Pl clarify. Appreciate an
early reply.
=20
[postgresql-8.2-US.pdf]
http://www.postgresql.org/files/documentation/pdf/8.2/postgr esql-8.2-US.
pdf
..pdf>=20
=20
Regards, Narasimha Murthy
Cell +91 95814 98895, +91-94940 62794 | 040-2347 2025 (O) | x2025 (O)
=20

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Re: Clarification Needed: When does autovacuum daemon run?

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On Tue, 2010-05-18 at 17:56 +0800, Narasimha Murthy-VRFX87 wrote:
> My Query: I want to run autovacuum daemon everyday at 5 am.=20

That is not "auto"vacuum. What you want is manual vacuum.
--=20
Devrim GÜNDÜZ
PostgreSQL Danışmanı/Consultant, Red Hat Certified Engineer
PostgreSQL RPM Repository: http://yum.pgrpms.org
Community: devrim~PostgreSQL.org, devrim.gunduz~linux.org.tr
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Re: Clarification Needed: When does autovacuum daemon run?

=20
Thanks Devrim and Ian, for a quick response.

I need some more clarification. autovacuum_naptime takes one minute by defa=
ult. In this case, which second of each minute the autovacuum daemon runs (=
provided it is enabled)? What is the "activity rounds" mentioned in the man=
ual?

Regards, Narasimha Murthy
Cell +91 95814 98895, +91-94940 62794 | 040-2347 2025 (O) | x2025 (O)

-----Original Message-----
From: Ian Lea [mailto:ian.lea@gmail.com]=20
Sent: Tuesday, May 18, 2010 3:43 PM
To: Narasimha Murthy-VRFX87
Subject: Re: [ADMIN] Clarification Needed: When does autovacuum daemon run?

As far as I understand it, the idea of autovacuum is that it chugs away tra=
nsparently in the background, keeping things healthy on a little but often =
basis. It is not designed to run once a day at a specific time. If that i=
s really what you want, I suggest you disable autovacuum and run vacuum man=
ually at 05:00.


--
Ian.


On Tue, May 18, 2010 at 10:56 AM, Narasimha Murthy-VRFX87 com> wrote:
> Hello,
>
> Postgresql-8.2 manual=A0has mentioned following points.
> * The autovacuum daemon, when enabled, runs every autovacuum_naptime=20
> seconds.
> * autovacuum_naptime (integer): Specifies the delay between "activity=20
> rounds" for the autovacuum daemon....The delay is measured in seconds,=20
> and the default is one minute (1m)....
>
> My Query: I want to run autovacuum daemon everyday at 5 am. By=A0setting=
=20
> autovacuum_naptime to 24*60*60 (# of seconds in a day), I can run the=20
> daemon everyday. But, how do I ensure the daemon runs at 5am? What is=20
> the "activity rounds" mentioned in the manual? Pl clarify. Appreciate an =
early reply.
>
> [postgresql-8.2-US.pdf]
> http://www.postgresql.org/files/documentation/pdf/8.2/postgr esql-8.2-U
> S.pdf
>
> Regards, Narasimha Murthy
> Cell +91 95814 98895, +91-94940 62794=A0| 040-2347=A02025 (O) | x2025 (O)
>

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Re: Clarification Needed: When does autovacuum daemon run?

Excerpts from Narasimha Murthy-VRFX87's message of mar may 18 05:56:26 -0=
400 2010:
> Hello,
> =20
> Postgresql-8.2 manual has mentioned following points.
> * The autovacuum daemon, when enabled, runs every autovacuum_naptime
> seconds.
> * autovacuum_naptime (integer): Specifies the delay between "activity
> rounds" for the autovacuum daemon....The delay is measured in seconds,
> and the default is one minute (1m)....
> =20
> My Query: I want to run autovacuum daemon everyday at 5 am.

You cannot do that with autovacuum currently. Use cron.
--=20

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Re: Clarification Needed: When does autovacuum daemon run?

Excerpts from Narasimha Murthy-VRFX87's message of mar may 18 07:04:34 -0=
400 2010:

> I need some more clarification. autovacuum_naptime takes one minute by
> default. In this case, which second of each minute the autovacuum
> daemon runs (provided it is enabled)?

Why does it matter which second it runs?

> What is the "activity rounds" mentioned in the manual??

Each worker start is a new round.
--=20

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Re: Clarification Needed: When does autovacuum daemon run?

Hi Alvaro Herrera,

Since, my original plan was to run the auto-vacuum daily EXACTLY at 5 am, I=
wanted to know which seconds of a minute. My query in other word was, if I=
set autovacuum_naptime to 1 hr, which minute of an hour the auto-vacuum ru=
ns (oth min, 15th min or something else).

From the clarification given by the you and other community members, I now =
understood that autovacuum is designed to run frequently in the background,=
not designed to run once a day at a specific time. Due to this design inte=
nt, autovacuum_naptime is set to 1 min by default and autovacuum runs lazy/=
plain/standard vacuum commands (so that Vacuum can run concurrently with ot=
her normal DB operations).

Regards, Narasimha Murthy
Cell +91 95814 98895, +91-94940 62794 | 040-2347 2025 (O) | x2025 (O)

-----Original Message-----
From: pgsql-admin-owner@postgresql.org [mailto:pgsql-admin-owner@postgresql=
..org] On Behalf Of Alvaro Herrera
Sent: Thursday, May 20, 2010 2:21 AM
To: Narasimha Murthy-VRFX87
Cc: Ian Lea; Devrim GÜNDÜZ; pgsql-admin
Subject: Re: [ADMIN] Clarification Needed: When does autovacuum daemon run?

Excerpts from Narasimha Murthy-VRFX87's message of mar may 18 07:04:34 -040=
0 2010:

> I need some more clarification. autovacuum_naptime takes one minute by=20
> default. In this case, which second of each minute the autovacuum=20
> daemon runs (provided it is enabled)?

Why does it matter which second it runs?

> What is the "activity rounds" mentioned in the manual??

Each worker start is a new round.
--=20

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Re: Clarification Needed: When does autovacuum daemon run?

Excerpts from Narasimha Murthy-VRFX87's message of jue may 20 02:47:21 -0=
400 2010:
> Hi Alvaro Herrera,
>=20
> Since, my original plan was to run the auto-vacuum daily EXACTLY at 5 a=
m, I wanted to know which seconds of a minute. My query in other word was=
, if I set autovacuum_naptime to 1 hr, which minute of an hour the auto-v=
acuum runs (oth min, 15th min or something else).

Yeah, you have no way to be know. I guess you could turn autovacuum off
in postgresql.conf all day, and exactly at 5am you have a cron job that
edits postgresql.conf and reloads Postgres. This would start up
autovacuum, which would then continue with the regular schedule.
This is hardly ideal; there were plans to improve on this by having an
autovacuum schedule, but I think the demand for this feature has
decreased considerable, so I haven't given it any minute's thought.

> From the clarification given by the you and other community members, I =
now understood that autovacuum is designed to run frequently in the backg=
round, not designed to run once a day at a specific time. Due to this des=
ign intent, autovacuum_naptime is set to 1 min by default and autovacuum =
runs lazy/plain/standard vacuum commands (so that Vacuum can run concurre=
ntly with other normal DB operations).

Correct.
--=20

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