On Wed, Jan 5, 2011 at 3:22 PM, Jesper Krogh <jes...@krogh.cc> wrote: > Given a crash-safe visibility map, what purpuse does the PD_ALL_VISIBLE bit > serve?
If we modify a page on which PD_ALL_VISIBLE isn't set, we don't attempt to update the visibility map. In theory, this is an important optimization to reduce contention on the visibility map page, since there are something like 64K heap pages per visibility map page. In practice, I'm not sure in what workloads it matters or by how much. -- 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
