On 7 October 2014 03:31, Peter Geoghegan <p...@heroku.com> wrote: >> It may be that people on reading this now believe Peter's HW locking >> approach is the best. I'm happy to go with consensus. > > I bet you didn't think that you'd say that a week ago. :-)
You're right, because last week I thought heavyweight locking sucks and I still think that; I haven't said it is the best. What we've just discovered is that we're locking 100% of the time, but its not needed in 99.9% of cases and is arguable in the 0.1% case - not "required" at all. The price of avoiding that rare and possibly erroneous condition seems high to me. Is there a way of detecting that we are updating a unique constraint column and then applying the HW locking only in that case? Or can we only apply locking when we have multiple unique constraints on a table? If so, I would withdraw any objection to the HW locking technique. -- Simon Riggs 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
