On Fri, May 25, 2012 at 10:30 AM, Merlin Moncure <mmonc...@gmail.com> wrote: > I think what's happening here is that the buffer partitions don't help > (in fact, they hurt) in the presence of multiple concurrent scans that > are operating on approximately the same data. Sooner or later the > scans line up on each other and start binding when reassigning lock > tags (which take out up to two ordered exclusive lwlocks). This is on > the read side, so the buffer access strategy is zero help (I confirmed > this off list).
This theory is seeming fairly plausible - how can we test it? How about trying it with synchronize_seqscans = off? If the synchronized-seqscan logic is causing contention on the buf mapping locks and individual buffer locks, that should fix it. -- 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
