On 2013-10-03 21:14:17 -0700, Dan Ports wrote: > On Thu, Oct 03, 2013 at 06:19:49AM -0700, Kevin Grittner wrote: > > Heikki Linnakangas <hlinnakan...@vmware.com> wrote: > > > IMHO it would be better to remove xmin from the lock key, and vacuum > > > away the old predicate locks when the corresponding tuple is vacuumed. > > > The xmin field is only required to handle the case that a tuple is > > > vacuumed, and a new unrelated tuple is inserted to the same slot. > > > Removing the lock when the tuple is removed fixes that. > > This seems definitely safe: we need the predicate locks to determine if > someone is modifying a tuple we read, and certainly if it's eligible > for vacuum nobody's going to be modifying that tuple anymore.
But we're talking about freezing a tuple, not removing a dead tuple. I don't see anything preventing modification of a frozen tuple. Right? 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
