On Thu, Apr 21, 2011 at 12:32 PM, Kevin Grittner <kevin.gritt...@wicourts.gov> wrote: > Robert Haas <robertmh...@gmail.com> wrote: > >> 1. All of the SSI patches have been dealt with. > > I'll add the non-serializable UPDATE performance issue. Dan has > been benchmarking to try to find a worst case; I don't want to speak > for him too much, but as he was headed off to lecture a class he > sent me results so far, and with beta so close I figure I should > pass along a rough outline. The worst case he has been able to > construct so far was running 32 active processes on a 16 processor > machine in an update-mostly mix against a database on tmpfs (so no > disk writes) on a dataset which fits inside shared_memory. This was > able to generate enough contention on an exclusive LW lock to cause > a 0.7% slowdown. > > Speaking for myself, I believe we'll be able to provide a very small > patch to eliminate this. Probably today or tomorrow. While in a > less extreme runtime environment it would probably be hard to pick > out a performance impact in the normal noise, I expect the fix to be > small and safe enough to be worth doing. > > I do feel that it would be good to apply the one-line fix Heikki > posted, which is orthogonal and needed in any event. That would > give a little time for others to easily test it before beta.
Please add that patch to the open items list if it is not there already. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
