On Wed, Jun 22, 2011 at 10:40 PM, Jeff Davis <pg...@j-davis.com> wrote: > 1. Torn pages -- not a problem because it's a single bit and idempotent.
Right. > 2. PD_ALL_VISIBLE bit makes it to disk before a WAL record representing > an action that makes the page all-visible. Depending on what action > makes a page all-visible: > a. An old snapshot is released -- not a problem, because if there is a > crash all snapshots are released. > b. Cleanup action on the page -- not a problem, because that will > create a WAL record and update the page's LSN before setting the > PD_ALL_VISIBLE. Lazy VACUUM is the only thing that makes a page all visible. I don't understand the part about snapshots. -- 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
