Re: immutable functions vs. join for lookups ?

* Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Enrico Weigelt <weigelt@metux.de> writes:
> > c) CREATE FUNCTION id2username(oid) RETURNS text
> >     LANGUAGE 'SQL' IMMUTABLE AS '
> >     SELECT username AS RESULT FROM users WHERE uid = $1';
>
> This is simply dangerous.  The function is *NOT* immutable (it is
> stable though).  When ... not if ... your application breaks because
> you got the wrong answers, you'll get no sympathy from anyone.

In my case it is immutable. The username never changes.


cu
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