Subject: Re: autovacuum
From: Scott Marlowe <smarlowe@g2switchworks.com>
To: Sriram Dandapani <sdandapani@counterpane.com>
Cc: pgsql-admin@postgresql.org
In-Reply-To: <6992E470F12A444BB787B5C937B9D4DF04C4C928@ca-mail1.cis.local>
References: <6992E470F12A444BB787B5C937B9D4DF04C4C928@ca-mail1.cis.local>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: quoted-printable
Message-Id: <1150315595.26538.28.camel@state.g2switchworks.com>
Mime-Version: 1.0
Date: Wed, 14 Jun 2006 15:06:35 -0500

On Wed, 2006-06-14 at 11:52, Sriram Dandapani wrote:
> Hi
>=20
> =20
>=20
> I have a table into which data flows at a high rate say 2 million rows
> per hour. Every 15 minutes, these rows are processed and deleted.=20
>=20
> At any point in time, the row count for the table hovers around 500K
> (due to the deletes).
>=20
> =20
>=20
> I have set max_fsm_pages to about 2000000. I still see the
> pg_total_relation_size constantly reporting an increasing size.=20
>=20
> =20
>=20
> How do I know if autovacuum is reclaiming space or is my max_fsm
> setting plain wrong. (I understand that autovacuum marks tuples for
> reuse, but shouldn=E2=80=99t pg_total_relation_size take that into accoun=
t)

I wouldn't really rely on just autovacuum to do this.
But, if you must, adjust the threshholds to have it trigger more easily.

Me personally, if I'm running a script that deletes 500,000 rows, I put
a vacuum at the end of it.  That way you KNOW the vacuum got run.