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Re: How do you control IMMUTABLE PG PROC results? - Mailing list pgsql-general

From Leif Biberg Kristensen
Subject Re: How do you control IMMUTABLE PG PROC results?
Date
Msg-id 201011050248.52574.leif@solumslekt.org
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In response to How do you control IMMUTABLE PG PROC results?  ("Carlo Stonebanks" <stonec.register@sympatico.ca>)
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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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