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