| From: | Leif Biberg Kristensen <leif(at)solumslekt(dot)org> |
|---|---|
| To: | pgsql-general(at)postgresql(dot)org |
| Subject: | Re: How do you control IMMUTABLE PG PROC results? |
| Date: | 2010-11-05 01:48:52 |
| Message-ID: | 201011050248.52574.leif@solumslekt.org |
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| Lists: | pgsql-general |
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
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