On 20 December 2012 00:10, Pavan Deolasee <pavan.deolasee@gmail.com> wrote:
> I just thought that we can fairly easily limit the damage if we are
> really worried about SELECTs being penalised. What if we set a
> configurable limit on *extra* things that a query may do which is
> otherwise not very useful for the query itself, but is useful to keep
> the system healthy and steady. HOT prune definitely counts as one of
> them and may be even setting of hint bits. (This is a topic for a
> separate thread though)
I like this idea
transaction_cleanup_limit = -1 (default), 0, 1+
-1 means no limit on number of cleanups in this transaction, which is
current behaviour.
Other numbers are the number of cleanups that will be tolerated in
this transaction; once we hit the limit we don't attempt cleanup
anymore we just get on with it. The limit is ignored for UPDATEs since
they need to clear space for their work.
-- Simon Riggs http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training & Services