On 3 October 2014 10:57, Peter Geoghegan <p...@heroku.com> wrote: > On Fri, Oct 3, 2014 at 2:50 AM, Simon Riggs <si...@2ndquadrant.com> wrote: >> My view is that I can't see the above use case from happening in real >> situations, except by infrequent mistake. In most cases, unique >> indexes represent some form of object identity and those don't change >> frequently in the real world. So to be changing two unique fields at >> the same time and it not representing some form of business process >> error that people would like to see fail anyway, I'd be surprised by. > > Are we talking about two different things here? > > Unprincipled deadlocks can be seen without updating any constrained > column in the UPSERT. The test-case that originally highlighted the > issue only had one unique index, and it was *not* in the update's > targetlist. See: > > https://wiki.postgresql.org/wiki/Value_locking#.22Unprincipled_Deadlocking.22_and_value_locking
I followed that to a wiki page, then clicked again to an old email. No test case. -- 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
