Subject: Re: Postgres becoming slow, only full vacuum fixes it
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From: Kiriakos Tsourapas <ktsour@gmail.com>
In-Reply-To: <5060E7F2.3010903@catalyst.net.nz>
Date: Tue, 25 Sep 2012 14:07:55 +0300
Cc: pgsql-performance@postgresql.org
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References: <D15ECA12-8D6E-4E53-A294-5E175564CA61@gmail.com>
	<5060E7F2.3010903@catalyst.net.nz>
To: Mark Kirkwood <mark.kirkwood@catalyst.net.nz>

Hi Mark,

When the problem appears, vacuuming is not helping. I ran vacuum =
manually and the problem was still there. Only full vacuum worked.

As far as I have understood, autovacuuming is NOT doing FULL vacuum. So, =
messing around with its values should not help me in any way.


Thanks


>=20
> Given that vacuum full fixes the issue I suspect you need to have =
autovacuum set wake up much sooner, not later. So autovacuum_naptime =3D =
28800 or even =3D 60 (i.e the default) is possibly too long. We have =
several database here where I change this setting to 10 i.e:
>=20
> autovacuum_naptime =3D 10s
>=20
>=20
> in order to avoid massive database bloat and queries that get slower =
and slower...
>=20
> You might want to be a bit *less* aggressive with =
autovacuum_vacuum_scale_factor - I usually have this at 0.1, i.e:
>=20
> autovacuum_vacuum_scale_factor =3D 0.1
>=20
>=20
> otherwise you will be vacuuming all the time - which is usually not =
what you want (not for all your tables anyway).
>=20
> regards
>=20
> Mark
>=20
>=20
> --=20
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