Bruce Momjian wrote: > > Yep, agreed on the random I/O issue. The larger question is if you have > a huge table, do you care to reclaim 3% of the table size, rather than > just vacuum it when it gets to 10% dirty? I realize the vacuum is going > to take a lot of time, but vacuuming to relaim 3% three times seems like > it is going to be more expensive than just vacuuming the 10% once. And > vacuuming to reclaim 1% ten times seems even more expensive. The > partial vacuum idea is starting to look like a loser to me again.
But if the partial vacuum is able to clean the busiest pages and reclaim useful space, currently-running transactions will be able to use that space and thus not have to extend the table. Not that extension is a problem on itself, but it'll keep your working set smaller. -- Alvaro Herrera http://www.CommandPrompt.com/ PostgreSQL Replication, Consulting, Custom Development, 24x7 support ---------------------------(end of broadcast)--------------------------- TIP 4: Have you searched our list archives? http://archives.postgresql.org/
