Tom Lane <tgl@sss.pgh.pa.us> writes:
> That surprises me too --- can you provide details on the test case so
> other people can reproduce it? AFAIR the only performance difference
> between SERIALIZABLE and READ COMMITTED is the frequency with which
> transaction status snapshots are taken; your report suggests you were
> spending 30% of the time in GetSnapshotData, which is a lot higher than
> I've ever seen in a profile.
Perhaps it reduced the amount of i/o concurrent vacuums were doing?
--
greg