2010/1/5 Roman Neuhauser <neuhauser+pgsql-general#postgresql....@sigpipe.cz>: > # jayadevan.maym...@ibsplc.com / 2010-01-04 10:03:29 +0530: >> This seems to work.. >> UPDATE x set i=i+1 >> from (select i as m from x order by m desc) y where x.i = y.m >> Jayadevan > > Thanks, that nicely achieves the illusion of atomic immediate checking. > > -- > Roman Neuhauser
That is not guaranteed to work. Depending on how the optimiser does the join, the reverse ordering may not be preserved in the update. Try it for larger tables (for me it fails at 100000 rows). Regards, Dean -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
