"John Lister" <john.lister...@kickstone.com> writes:
> Hi, I'm running 8.3.9 on ubuntu with autovacuum enabled and seemingly
> working properly., however I've started getting messages saying that I'm near
> the transaction limit and I need to do a database wide vacuum, which I've
> started.
> From reading the docs, though I thought that autovacuum would do this on my
> behalf, is this true?
It's supposed to. Did you look around to see if AV was trying to do
anything?
It's possible you got bit by this recently-fixed bug, which caused any
large-scale autovacuum operation to take unreasonably long to complete:
Author: Tom Lane <t...@sss.pgh.pa.us>
Branch: master [b58c25055] 2010-11-19 22:28:20 -0500
Branch: REL9_0_STABLE Release: REL9_0_2 [b5efc0940] 2010-11-19 22:28:25 -0500
Branch: REL8_4_STABLE Release: REL8_4_6 [fab2af30d] 2010-11-19 22:28:30 -0500
Branch: REL8_3_STABLE Release: REL8_3_13 [6cb9d5113] 2010-11-19 22:28:35 -0500
Fix leakage of cost_limit when multiple autovacuum workers are active.
When using default autovacuum_vac_cost_limit, autovac_balance_cost relied
on VacuumCostLimit to contain the correct global value ... but after the
first time through in a particular worker process, it didn't, because we'd
trashed it in previous iterations. Depending on the state of other autovac
workers, this could result in a steady reduction of the effective
cost_limit setting as a particular worker processed more and more tables,
causing it to go slower and slower. Spotted by Simon Poole (bug #5759).
Fix by saving and restoring the GUC variables in the loop in do_autovacuum.
In passing, improve a few comments.
Back-patch to 8.3 ... the cost rebalancing code has been buggy since it was
put in.
regards, tom lane
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