Oops! [EMAIL PROTECTED] (Bruce Momjian) was seen spray-painting on a wall: > That could be part of auto-vacuum. Vacuum itself would still > sequential scan, I think. The idea is to easily grab expire tuples > when they are most cheaply found.
The nifty handling of this would be to introduce "VACUUM CACHE", which would simply walk through the shared memory cache to look for expiries there. That could have a most interesting interaction with ARC... On the "unfortunate" side, marking tuples as dead would, I believe draw in some index pages. (Right?) Those pages drawn in would remain at the "cheapest" end of the cache; an ARC 'win.' And it should be the case that this ultimately shrinks cache usage, as dead tuples get thrown out. Running VACUUM CACHE periodically on a system that is "killing" tuples at a pretty steady clip ought to clear out many of those tuples without needing to browse the tables. This ought to be particularly helpful with large tables that have small "contentious" portions that generate dead tuples. -- let name="cbbrowne" and tld="gmail.com" in name ^ "@" ^ tld;; http://www.ntlug.org/~cbbrowne/rdbms.html "Heuristics (from the French heure, "hour") limit the amount of time spent executing something. [When using heuristics] it shouldn't take longer than an hour to do something." ---------------------------(end of broadcast)--------------------------- TIP 7: don't forget to increase your free space map settings
