On Tue, Jan 04, 2011 at 07:02:54PM +0200, Marko Tiikkaja wrote: > On 2011-01-04 6:27 PM, David Fetter wrote: > >On Tue, Jan 04, 2011 at 04:44:32AM -0500, Greg Smith wrote: > >>Heikki Linnakangas wrote: > >>>You can of course LOCK TABLE as a work-around, if that's what you want. > >> > >>Presuming the code quality issues and other little quirks I've > >>documented (and new ones yet to be discovered) can get resolved > >>here, and that's a sizeable open question, I could see shipping this > >>with the automatic heavy LOCK TABLE in there. Then simple UPSERT > >>could work out of the box via a straightforward MERGE. > > > >How about implementing an UPSERT command as "take the lock, do the > >merge?" That way, we'd have both the simplicity for the simpler cases > >and a way to relax consistency guarantees for those who would like to > >do so. > > That, unfortunately, won't work so well in REPEATABLE READ :-(
There are caveats all over READ COMMITTED/REPEATABLE READ/SNAPSHOT. The only really intuitively obvious behavior is SERIALIZABLE, which we'll have available in 9.1. :) > But I, too, am starting to think that we should have a separate, > optimized command to do UPSERT/INSERT .. IGNORE efficiently and > correctly while making MERGE's correctness the user's > responsibility. Preferably with huge warning signs on the > documentation page. +1 for the HUGE WARNING SIGNS :) Cheers, David. -- David Fetter <da...@fetter.org> http://fetter.org/ Phone: +1 415 235 3778 AIM: dfetter666 Yahoo!: dfetter Skype: davidfetter XMPP: david.fet...@gmail.com iCal: webcal://www.tripit.com/feed/ical/people/david74/tripit.ics Remember to vote! Consider donating to Postgres: http://www.postgresql.org/about/donate -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
