Dan Ports <d...@csail.mit.edu> wrote: > I was doing some tests recently with default_transaction_isolation > set to 'serializable' in postgresql.conf when I noticed pg_locks > filling up with SIReadLocks rather more quickly than I expected. > > 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. > > My one-liner fix for this was to set > DefaultXactIsoLevel = XACT_READ_COMMITTED; > in AutoVacWorkerMain. Ouch! I think this needs to be considered a significant bug! Is it too late to get this into 9.1.2? -Kevin
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