On 2014-04-23 16:30:05 -0300, Alvaro Herrera wrote: > Andres Freund wrote: > > > I think this patch is a seriously bad idea. For one, it's not actually > > doing anything about the problem - the tuple can be accessed without > > freezing getting involved. > > Normal access other than freeze is not a problem, because other code > paths do check for HEAP_XMAX_INVALID and avoid access to Xmax if that's > set. > > > For another, it will increase wall traffic for freezing of short lived > > tuples considerably, without any benefit. > > True. I didn't actually try to run this; it was just for demonstration > purposes. It'd need some cooperation from heap_tuple_needs_freeze in > order to work at all, for one thing.
I think if you want to add something like this it should be added *inside* the if (MultiXactIdPrecedes(multi, cutoff_multi)) block in FreezeMultiXactId(). There it seems to make quite a bit of sense. Greetings, Andres Freund -- Andres Freund 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
