On Wed, Aug 22, 2012 at 5:31 PM, Alvaro Herrera <alvhe...@2ndquadrant.com> wrote: > Patch v19 contains some tweaks. Most notably, > > 1. if an Xid requests a lock A, and then a lock B which is stronger than > A, then record only lock B and forget lock A. This is important for > performance, because EvalPlanQual obtains ForUpdate locks on the tuples > that it chases on an update chain. If EPQ was called by an update or > delete, previously a MultiXact was being created. > > In a stock pgbench run this was causing lots of multis to be created, > even when there are no FKs. > > This was most likely involved in the 9% performance decrease that was > previously reported.
Ah-ha! Neat. I'll try to find some time to re-benchmark this during the next CF, unless you did that already. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (firstname.lastname@example.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers