Marco Bizzarri wrote: > Hi all. > > I need to keep a numer of counters in my application; my counters are > currently stored in a table: > > name | next_value | year > > > The counters must be progressive numbers with no holes in between > them, and they must restart from 1 every year. What I've done so far > is to access them while in SERIALIZABLE ISOLATION LEVEL, with the > following: > > SELECT next_value FROM counters WHERE name = 'name' for update; > UPDATE counters SET next_value = next_value + 1 WHERE name = 'name'; If you're using a sufficiently recent version of Pg you can use: UPDATE counters SET next_value = next_value + 1 WHERE name = 'name' RETURNING next_value; instead, which is slightly nicer. It'll return the *new* value of `next_value', so you'd have to make a few tweaks. -- Craig Ringer
