On Wed, 2010-10-20 at 16:10 -0400, Michael Glaesemann wrote: > Upgrade if you can. Otherwise you can do two updates when rearranging > paragraphs. The first updates them to an "invalid" range which isn't used in > "correct" data and so won't conflict with other values, and the second moves > them back to the valid range of positions. > Negative numbers are often used for this middle range.
The reason for the upgrade suggestion I believe was DEFERRABLE unique constraints. These allow you to temporarily violate a unique constraint, as long as it's correct at the end. See: http://www.postgresql.org/docs/9.0/static/sql-createtable.html and look for "DEFERRABLE". You can also consider a constraint trigger: http://www.postgresql.org/docs/9.0/static/sql-createconstraint.html Be careful to lock appropriately, however. Regards, Jeff Davis -- Sent via pgsql-general mailing list ([email protected]) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
