Simon Riggs wrote: > I notice that during copy_heap_data() we make no attempt to skip pages > that are all visible according to the visibilitymap. It seems like it > would be a substantial win to copy whole blocks if all the > pre-conditions are met (I see what they are). I'm surprised to see that > neither CLUSTER nor VACUUM FULL made use of this previously. I think we > either need to implement that or document that vacuum will not skip > all-visible pages when running VACUUM FULL.
Unfortunately the visibility map isn't completely crash-safe at the moment (see comments in visibilitymap.c for details). So it's not safe to use it for such purposes. I was planning to address that in 8.5 but it seems I won't have the time. -- Heikki Linnakangas EnterpriseDB http://www.enterprisedb.com -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
