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 will also note that the behavior of holding pin for as long as we are > stopped on a particular tuple is not specific to seqscans. Agreed. Bad things may happen in more than one place. -- Simon Riggs http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
