Re: VACUUM and open transactions

From: Joseph S <jks(at)selectacast(dot)net>
To: pgsql-general(at)postgresql(dot)org
Subject: Re: VACUUM and open transactions
Date: 2007-01-31 01:15:19
Message-ID: 45BFEDA7.8060202@selectacast.net
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I realize this thread is old, but I just conducted an experiment with pg
8.0.10 and a transaction with a SERIALIZABLE isolation level does
prevent VACUUM from reclaiming rows that were created and then obsoleted
in a subsequent transaction.

Martijn van Oosterhout wrote:
> On Thu, Oct 19, 2006 at 04:25:09PM -0400, Joseph S wrote:
>>> The problem is that the "old" transaction can see effects of later
>>> started transactions, so VACUUM can't delete the later stuff either...
>> How can it see effects of transactions that started after it?
>
> Check the documentation for the difference the READ COMMITTED and
> SERIALIZABLE transaction. The former (the default) will see the results
> of any committed transactions, even if they started later.
>
> http://www.postgresql.org/docs/8.1/interactive/transaction-iso.html#XACT-READ-COMMITTED
>
> Have a nice day,

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