"Pavel Stehule" <[EMAIL PROTECTED]> writes: > Hello, > > I did small tests and I found so for small tables (less 1000 rows) > VACUUM based on visibility maps are slower than old implementation > > it is about 5ms X 20ms
Hm, Presumably this is on a machine where the visibility map is entirely in cache too. On a busy machine that's stealing a page from other table's cache. The conservative thing to do would be to avoid creating a visibility map for tables unless they're large enough that it's incontrovertibly enough of a gain. Especially since speeding up short-lived vacuums doesn't seem terribly interesting. Without index-only scans it probably doesn't make much sense to create the visibility map until we hit something like 32 pages or so. Vacuum should be able to handle that many pages so fast that speeding it up seems pointless. -- Gregory Stark EnterpriseDB http://www.enterprisedb.com Ask me about EnterpriseDB's 24x7 Postgres support! -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
