On Fri, Mar 25, 2011 at 3:32 PM, Heikki Linnakangas <heikki.linnakan...@enterprisedb.com> wrote: > On 25.03.2011 16:52, Merlin Moncure wrote: >> >> Without this bit, the only way to set hint bits going during bufmgr >> eviction is to do a visibility check on every tuple, which would >> probably be prohibitively expensive. > > I don't think the naive approach of scanning all tuples would be too bad, > actually. The hint bits only need to be set once, and it'd be bgwriter > shouldering the overhead.
I was thinking the same thing. The only thing I'm worried about is whether it'd make the bgwriter less responsive; we already have some issues in that department. > The problem with setting hing bits when a buffer is evicted is that it > doesn't help with the bulk load case. The hint bits can't be set for a bulk > load until the load is finished and the transaction commits. > > Maybe it would still be worthwhile to have bgwriter set hint bits, to reduce > I/O caused by hint bit updates in an OLTP workload, but that's not what > people usually complain about. Yeah. -- 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
