On Friday 5. November 2010 01.24.14 Carlo Stonebanks wrote:
> We have procs that would benefit from returning IMMUTABLE results. The procs
> are dependent on external tables that rarely change, but when they DO
> change, it would be great if we could expire the cache that the procs read
> from so that the procs are forced to re-evaluate the results.
A function declared as IMMUTABLE can't, by definition, do database lookups.
Then it has to be declared as STABLE.
<http://www.postgresql.org/docs/8.4/static/xfunc-volatility.html>
«An IMMUTABLE function cannot modify the database and is guaranteed to return
the same results given the same arguments forever.»
regards,
Leif B. Kristensen