On 1 June 2013 21:26, Robert Haas <robertmh...@gmail.com> wrote: > On Sat, Jun 1, 2013 at 3:22 PM, Simon Riggs <si...@2ndquadrant.com> wrote: >> If we set a bit, surely we need to write the page. Isn't that what we >> were trying to avoid? > > No, the bit only gets set in situations when we were going to dirty > the page for some other reason anyway. Specifically, if a page > modification discovers that we've switched epochs (but just once) and > the bit isn't already set, we can set it in lieu of scanning the > entire page for tuples that need freezing. > > Under this proposal, pages that don't contain any dead tuples needn't > be dirtied for freezing, ever. Smells like awesome.
Agreed, well done both. What I especially like about it is how little logic it will require, and no page format changes. -- 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
