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Re: function side effects

From: Jaime Casanova <jcasanov(at)systemguards(dot)com(dot)ec>
To: Peter Eisentraut <peter_e(at)gmx(dot)net>
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 20:30:20
Message-ID: 3073cc9b1003011230m13ba722ao2df305ba65b67dce@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-hackers
On Mon, Mar 1, 2010 at 2:56 PM, Peter Eisentraut <peter_e(at)gmx(dot)net> wrote:
> 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
>

good!

> Notice also that this is separate from
>
> <deterministic characteristic> ::=
> DETERMINISTIC
> | NOT DETERMINISTIC
>

so IMMUTABLE = DETERMINISTIC NO SQL,
STABLE = DETERMINISTIC READS SQL DATA
VOLATILE = NOT DETERMINISTIC MODIFIES SQL DATA

> which is the SQL standard's variant of volatility.
>
> So someone has already had the idea that these two should exist
> separately.
>

seems something we should implement

-- 
Atentamente,
Jaime Casanova
Soporte y capacitación de PostgreSQL
Asesoría y desarrollo de sistemas
Guayaquil - Ecuador
Cel. +59387171157

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