On Tue, Jun 7, 2011 at 8:24 PM, Greg Stark <gsst...@mit.edu> wrote: > On Mon, Jun 6, 2011 at 11:30 PM, Simon Riggs <si...@2ndquadrant.com> wrote: >> But I think you've hit the important point here. The problem is not >> whether VACUUM waits for the pin, its that the pins can be held for >> extended periods. > > Yes > >> It makes more sense to try to limit pin hold times than it does to >> come up with pin avoidance techniques. > > Well it's super-exclusive-vacuum-lock avoidance techniques. Why > shouldn't it make more sense to try to reduce the frequency and impact > of the single-purpose outlier in a non-critical-path instead of > burdening every other data reader with extra overhead? > > I think Robert's plan is exactly right though I would phrase it > differently. We should get the exclusive lock, freeze/kill any xids > and line pointers, then if the pin-count is 1 do the compaction.
Would that also be possible during recovery? A similar problem exists with Hot Standby, so I'm worried fixing just VACUUMs would be a kluge. -- Simon Riggs http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
