On 2012-12-13 17:29:06 -0500, Robert Haas wrote: > On Thu, Dec 13, 2012 at 3:03 PM, Andres Freund <and...@2ndquadrant.com> wrote: > > It moves a computation of the sort of: > > > > result -= vacuum_defer_cleanup_age; > > if (!TransactionIdIsNormal(result)) > > result = FirstNormalTransactionId; > > > > inside ProcArrayLock. But I can't really imagine that to be relevant... > > I can. Go look at some of the 9.2 optimizations around > GetSnapshotData(). Those made a BIG difference under heavy > concurrency and they were definitely micro-optimization. For example, > the introduction of NormalTransactionIdPrecedes() was shockingly > effective.
But GetOldestXmin() should be called less frequently than GetSnapshotData() by several orders of magnitudes. I don't really see it being used in any really hot code paths? Greetings, Andres Freund -- Andres Freund http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
