On Wed, Nov 7, 2012 at 10:21 AM, Andres Freund <andres@xxxxxxxxxxx> wrote: > On Tue, Nov 06, 2012 at 02:55:40PM -0800, Mike Lewis wrote: >> I am trying to make a trigger that updates a row once and only once per >> transaction (even if this trigger gets fired multiple times). The general >> idea is that for a user we have a version number. When we modify the >> user's data, the version number is incremented then set on the object. We >> only need to increment the version number once. >> >> I am thinking about doing something like: >> >> update user >> set version=version+1 >> where txid_current() != xmin and user_id = 352395; >> >> >> So I guess my questions are: >> >> How dirty is this? >> Will I run into issues? > > It won't work in the presenence of subtransactions and is a bit more > complicated if you inserted the row in the same transaction. This can be solved by storing txid_current() into row and using that in comparision instead xmin/xmax. -- marko -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
