On 2013-09-20 13:53:04 +0200, Andres Freund wrote: > Hi, > > > On 2013-09-20 13:55:36 +0300, Heikki Linnakangas wrote: > > When a tuple is predicate-locked, the key of the lock is ctid+xmin. However, > > when a tuple is frozen, its xmin is changed to FrozenXid. That effectively > > invalidates any predicate lock on the tuple, as checking for a lock on the > > same tuple later won't find it as the xmin is different. > > > > Attached is an isolationtester spec to demonstrate this. > > Do you have any idea to fix that besides keeping the xmin horizon below the > lowest of the xids that are predicate locked? Which seems nasty to > compute and is probably not trivial to fit into the procarray.c > machinery?
A better solution probably is to promote tuple-level locks if they exist to a relation level one upon freezing I guess? 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
