Peter Eisentraut wrote:
On Thursday 28 May 2009 04:49:19 Tom Lane wrote:
Yeah. The fundamental problem with all the "practical" approaches I've
heard of is that they only work for a subset of possible predicates
(possible WHERE clauses). The idea that you get true serializability
only if your queries are phrased just so is ... icky. So icky that
it doesn't sound like an improvement over what we have.
Is it even possible to have a predicate locking implementation that can verify
whether an arbitrary predicate implies another arbitrary predicate?
I don't think you need that for predicate locking. To determine if e.g
an INSERT and a SELECT conflict, you need to determine if the INSERTed
tuple matches the predicate in the SELECT. No need to deduce anything
between two predicates, but between a tuple and a predicate.
--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com
--
Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-hackers
