Re: BUG #4059: Vacuum full not always cleaning empty tables

Yes, there are transactions that predate the start time of the vacuum full.
However those transactions do not touch the table being vacuumed, they have
nothing to do with it. Is this the expected behavior?

Mark Steben
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-----Original Message-----
From: Alvaro Herrera [mailto:alvherre(at)commandprompt(dot)com]
Sent: Tuesday, March 25, 2008 9:24 PM
To: Mark Steben
Cc: pgsql-bugs(at)postgresql(dot)org
Subject: Re: [BUGS] BUG #4059: Vacuum full not always cleaning empty tables

Mark Steben wrote:

> I sent an email to 'pgsql-bugs(at)postgresql(dot)org' entitled
> 'Possible bug with VACUUM FULL' and also an addendum
> But neglected to also send this bug report form.
> You can refer to those emails; in a nutshell, I have found that VACUUM
FULL
> will not clean dead tuples out of an empty table when other queries are
> accessing the database. Test plans/scenarios are included.

Yes, if other sessions have open transactions whose start time predate
the start time of the transaction that deletes of tuples, those tuples
cannot be removed by VACUUM. This is known and expected. Is this
what's happening here?

--
Alvaro Herrera http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.