On May 13, 2010, at 23:51 , Kevin Grittner wrote: > Florian Pflug <f...@phlo.org> wrote: > >> All in all, I believe that SHARE and UPDATE row-level locks should >> be changed to cause concurrent UPDATEs to fail with a >> serialization error. I can come up with a patch that does that, >> but I wanted to get some feedback on the idea before I put the >> work in. > > Before you work on that, you might want to wait until you can review > the work that I and Dan Ports (a Ph.D. candidate from MIT) have been > doing on support for true serializable transactions. You don't need > to use FOR SHARE or FOR UPDATE or any explicit locks as long as the > concurrent transactions are SERIALIZABLE. We have it working, but > have been holding off on discussion or patch submission at Tom's > request -- he felt it would distract from the process of getting the > release out.
I'm very exited about the work you're doing there, and believe it'd be a great feature to have. However, I view my proposal as pretty orthogonal to that work. True serializable transaction are much more powerful than what I proposed, but at a much higher price too, due to the necessity of SIREAD locks. My proposal allows for simple FK-like constraints to be implemented at user-level that are correct for all isolation levels. best regards, Florian Pflug -- Sent via pgsql-hackers mailing list (firstname.lastname@example.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers