On Mon, Jan 22, 2007 at 06:42:09PM +0000, Simon Riggs wrote: > On Mon, 2007-01-22 at 13:27 -0500, 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. > > Hold that thought! Read Heikki's Piggyback VACUUM idea on new thread... > > -- > Simon Riggs > EnterpriseDB http://www.enterprisedb.com > There may be other functions that could leverage a similar sort of infrastructure. For example, a long DB mining query could be registered with the system. Then as the pieces of the table/database are brought in to shared memory during the normal daily DB activity they can be acquired without forcing the DB to run a very I/O expensive query when waiting a bit for the results would be acceptable. As long as we are thinking piggyback. Ken
