Re: Clarification required: autovacuum and VACUUM command mode

Hi Kevin,

Thanks for the clarification.

I have planned to schedule Lazy Vacuum (, not FULL Vacuum) using auto-vacuum daemon.

Another query: I do not want to run Analyze. However, auto-vacuum runs both both VACUUM and ANALYZE. I do not see any option to disable running ANALYZE during auto-vacuum. Is there any way to achive this?

Pl clarify.

Regards, Narasimha Murthy
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-----Original Message-----
From: Kevin Grittner [mailto:Kevin(dot)Grittner(at)wicourts(dot)gov]
Sent: Friday, May 14, 2010 7:10 PM
To: Narasimha Murthy-VRFX87
Cc: pgsql-admin(at)postgresql(dot)org
Subject: Re: [ADMIN] Clarification required: autovacuum and VACUUM command mode

"Narasimha Murthy-VRFX87" <VRFX87(at)motorola(dot)com> wrote:
> Guillaume Lelarge <guillaume(at)lelarge(dot)info> wrote:
>> Le 14/05/2010 14:52, Narasimha Murthy-VRFX87 a écrit :

>>> VACUUM command works either in plain mode (if we do not specify
>>> FULL) or in FULL mode. When autovacuum is enabled, what mode does it
>>> run the VACUUM command (in plain mode or in FULL mode)?
>>
>> In plain mode.

> How do I check this? Please clarify.

http://www.postgresql.org/docs/8.2/interactive/routine-vacuuming.html#VACUUM-FOR-SPACE-RECOVERY

Since VACUUM FULL is not recommended for routine use, it would hardly make sense to use it for autovacuum. If you want to confirm, try selecting from a table while autovacuum is vacuuming it -- since VACUUM FULL locks the table against all other uses, the ability to select proves it's not VACUUM FULL.

By the way, I hope you're not considering scheduling regular VACUUM FULL runs against your database. You would wind up regretting that.
If you don't believe that, I recommend that you reread the above-cited section until you're convinced.

-Kevin