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Re: Minimally avoiding Transaction Wraparound in VLDBs

From: Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org>
To: Simon Riggs <simon(at)2ndquadrant(dot)com>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Minimally avoiding Transaction Wraparound in VLDBs
Date: 2005-09-01 01:48:04
Message-ID: 20050901014804.GA18701@surnet.cl (view raw or flat)
Thread:
Lists: pgsql-hackers
On Thu, Sep 01, 2005 at 01:57:02AM +0100, Simon Riggs wrote:

> > If you're using autovacuum then the problem is already taken care of.
> 
> autovacuum will respond only to UPDATEs and DELETEs. In the scenario I
> outline, these will *never* occur on the largest tables. A VACUUM would
> still eventually be required to freeze long lived tuples and this would
> not be performed by autovacuum.

Hum, I don't understand -- if you don't want to vacuum the table, why
run vacuum at all?  You can (as of 8.1) disable autovacuum for specific
tables.  The exception is that you are forced to run a database-wide
VACUUM once in a while (every billion-and-so), but this will hopefully
disappear in 8.2 too, leaving you effectively with the option of never
vacuuming a table.

-- 
Alvaro Herrera -- Valdivia, Chile         Architect, www.EnterpriseDB.com
You liked Linux a lot when he was just the gawky kid from down the block
mowing your lawn or shoveling the snow. But now that he wants to date
your daughter, you're not so sure he measures up. (Larry Greenemeier)

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