On Wed, Nov 9, 2011 at 6:10 PM, Simon Riggs <si...@2ndquadrant.com> wrote: > On Wed, Nov 9, 2011 at 10:20 PM, Tom Lane <t...@sss.pgh.pa.us> wrote: >> Simon Riggs <si...@2ndquadrant.com> writes: >>> heapgetpage() gets a page and a pin, but holds the pin until it reads >>> the next page. Wow! >> >>> That is both annoying and very dumb. It should hold the pin long >>> enough to copy the data and then release the pin. >> >> I don't find that anywhere near as obvious as you seem to. I think you >> are trying to optimize for the wrong set of conditions. > > ISTM we should optimise to access the cachelines in the buffer once. > Holding a pin and re-accessing the buffer via main memory seems pretty > bad plan to me. Which conditions are being optimised by doing that?
I believe it reduces memory copying. But we can certainly test some alternative you may have in mind and see how it shakes out. -- 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
