Re: PL/SQL & unset custom variable

(I'm using Postgres 8.3)

I have a trigger that references a custom variable. Most of the time this
custom variable is set, and I have no problems.

However, in certain corner cases the custom variable is not set and the
trigger fails.

Is there a way to either test if the custom variable is set, or to specify a
global default for the custom variable ?

Thanks,

GTG

Gordon Ross <gr306(at)ucs(dot)cam(dot)ac(dot)uk> wrote:

> (I'm using Postgres 8.3)
>
> I have a trigger that references a custom variable. Most of the time this
> custom variable is set, and I have no problems.
>
> However, in certain corner cases the custom variable is not set and the
> trigger fails.
>
> Is there a way to either test if the custom variable is set, or to specify a
> global default for the custom variable ?

I think, you can use COALESCE(your_variable, default_value) to solve
that problem. Try it, it is untested.

Andreas
--
Really, I'm not out to destroy Microsoft. That will just be a completely
unintentional side effect. (Linus Torvalds)
"If I was god, I would recompile penguin with --enable-fly." (unknown)
Kaufbach, Saxony, Germany, Europe. N 51.05082°, E 13.56889°

On 02/09/2009 15:39, "Andreas Kretschmer" <akretschmer(at)spamfence(dot)net> wrote:
> Gordon Ross <gr306(at)ucs(dot)cam(dot)ac(dot)uk> wrote:
>> Is there a way to either test if the custom variable is set, or to specify a
>> global default for the custom variable ?
>
> I think, you can use COALESCE(your_variable, default_value) to solve
> that problem. Try it, it is untested.

Sorry, no joy :-(

grails=> SELECT current_setting('phone.id');
ERROR: unrecognized configuration parameter "phone.id"

grails=> SELECT coalesce(current_setting('phone.id'),'SYSTEM');
ERROR: unrecognized configuration parameter "phone.id"

GTG

Gordon Ross <gr306(at)ucs(dot)cam(dot)ac(dot)uk> writes:
> Sorry, no joy :-(

> grails=> SELECT current_setting('phone.id');
> ERROR: unrecognized configuration parameter "phone.id"

> grails=> SELECT coalesce(current_setting('phone.id'),'SYSTEM');
> ERROR: unrecognized configuration parameter "phone.id"

You could use a SELECT from pg_settings to probe for the value
of the parameter without getting an error.

regards, tom lane

Hmmm.

If I do:

select * from pg_settings where name='custom_variable_classes';

I see my entry "phone", but I can't see how I can tell if I've set "phone.id"

GTG
________________________________________
From: Tom Lane [tgl(at)sss(dot)pgh(dot)pa(dot)us]
Sent: 02 September 2009 19:16
To: Gordon Ross
Cc: pgsql-general(at)postgresql(dot)org
Subject: Re: [GENERAL] PL/SQL & unset custom variable

Gordon Ross <gr306(at)ucs(dot)cam(dot)ac(dot)uk> writes:
> Sorry, no joy :-(

> grails=> SELECT current_setting('phone.id');
> ERROR: unrecognized configuration parameter "phone.id"

> grails=> SELECT coalesce(current_setting('phone.id'),'SYSTEM');
> ERROR: unrecognized configuration parameter "phone.id"

You could use a SELECT from pg_settings to probe for the value
of the parameter without getting an error.

regards, tom lane