Re: function side effects

From: Peter Eisentraut <peter_e(at)gmx(dot)net>
To: Jaime Casanova <jcasanov(at)systemguards(dot)com(dot)ec>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Greg Stark <gsstark(at)mit(dot)edu>, Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov>, Tatsuo Ishii <ishii(at)postgresql(dot)org>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: function side effects
Date: 2010-03-01 19:56:30
Message-ID: 1267473390.7837.9.camel@vanquo.pezone.net
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On tis, 2010-02-23 at 16:54 -0500, Jaime Casanova wrote:
> On Tue, Feb 23, 2010 at 2:02 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> >
> > There may be some value in inventing a "has no side effects" marker, but
> > that should not be confused with IMMUTABLE/STABLE.
> >
>
> a READONLY function?

SQL standard:

<SQL-data access indication> ::=
NO SQL
| CONTAINS SQL
| READS SQL DATA
| MODIFIES SQL DATA

Notice also that this is separate from

<deterministic characteristic> ::=
DETERMINISTIC
| NOT DETERMINISTIC

which is the SQL standard's variant of volatility.

So someone has already had the idea that these two should exist
separately.

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