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Re: autovacuum and default_transaction_isolation

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Dan Ports <drkp(at)csail(dot)mit(dot)edu>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: autovacuum and default_transaction_isolation
Date: 2011-11-30 00:04:23
Message-ID: 11274.1322611463@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-hackers
Dan Ports <drkp(at)csail(dot)mit(dot)edu> writes:
> After some investigation, I found that an autovacuum worker was
> starting a transaction at the default isolation level. While using a
> serializable transaction doesn't affect its behavior (because it's not
> using a MVCC snapshot), having a serializable transaction open prevents
> other concurrent serializable transactions and their predicate locks
> from being cleaned up. Since VACUUM on a large table can take a long
> time, this could affect many concurrent transactions.

Hmm.  Shouldn't we make the autovac launcher use READ COMMITTED, too?

			regards, tom lane

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