On Tue, Nov 6, 2012 at 2:55 PM, Mike Lewis <mikelikespie@xxxxxxxxx> 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? > Is there a better way of doing this? AFAIU it will work without issues. However I would use an additional "modified" column that is set by trigger every time the row is updated (and inserted) to the current time stamp and use it instead of txid_current()/xmin. The only my reason is that it can give me more control than txid based solution, for example if I need to set the modified column from outside, say to sync it with some another database shard's data. -- a database and software architect http://www.linkedin.com/in/grayhemp Jabber: gray.ru@xxxxxxxxx Skype: gray-hemp Phone: +14158679984 -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
