On Fri, Aug 14, 2009 at 12:07 AM, Josh Berkus<j...@agliodbs.com> wrote: > "freeze this table agressively if it's in memory, but wait a long time > to vaccuum if it's on disk"
Waitasec, "in memory"? There are two projects here: 1) Make vacuum when it's freezing tuples freeze every tuple > lesser age if it finds any tuples which are > max_age (or I suppose if the page is already dirty due to vacuum or something else). Vacuum still has to read in all the pages before it finds out that they don't need freezing so it doesn't mean distinguishing "in memory" from "needs to be read in". 2) Have something like bgwriter check if the page is dirty and vacuum and freeze things based on the lesser threshold. This would effectively only be vacuuming things that are "in memory" However the latter is a more complex and frought project. We looked at this a while back in EDB and we found that the benefits were less than we expected and the complexities more than we expected. I would recommend sticking with (1) for now and only looking at (2) if we have a more detailed plan and solid testable use cases. -- greg http://mit.edu/~gsstark/resume.pdf -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
