| From: | Scott Marlowe <smarlowe(at)g2switchworks(dot)com> |
|---|---|
| To: | "Ed L(dot)" <pgsql(at)bluepolka(dot)net> |
| Cc: | pgsql-general(at)postgresql(dot)org |
| Subject: | Re: vacuum vs open transactions |
| Date: | 2005-01-12 18:10:59 |
| Message-ID: | 1105553458.24795.7.camel@state.g2switchworks.com |
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| Thread: | |
| Lists: | pgsql-general |
On Wed, 2005-01-12 at 11:59, Ed L. wrote:
> I'm looking at some 7.3.4 vacuum output, and at first glance it does not
> appear that vacuum is reclaiming any dead tuple space if there is even a
> single open transaction, even if the open transaction does not in any way
> reference the table being vacuumed. Is that correct? Is the behavior
> different in later versions?
I believe the problem is occurring if the open transaction is older than
the tuples that could be vacuumed. The MVCC system means that as long
as a transaction that started X hours ago is still open, the tuples that
have been freed since then can't vacuumed because they need to stay
visible for that transaction.
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