Re: query to select a linked list

On Wed, May 09, 2007 at 02:55:20PM +0200, Louis-David Mitterrand wrote:
> Hi,
>
> To build a threaded forum application I came up the following schema:
>
> forum
> ------
> id_forum | integer| not null default nextval('forum_id_forum_seq'::regclass)
> id_parent| integer|
> subject | text | not null
> message | text |
>
> Each message a unique id_forum and an id_parent pointing to the replied
> post (empty if first post).
>
> How can I build an elegant query to select all messages in a thread?

I am trying to write a recursive pl/sql function to return all thread
children:

create or replace function forum_children(integer) returns setof forum as $$
declare
rec record;
begin

for rec in select * from forum where $1 in (id_parent,id_forum) loop

select * from forum_children(rec.id_forum);
return next rec;

end loop;

return;

end;
$$ language 'plpgsql';

But it does not work as intended (infinite loop?).

What did I miss?