Re: easy task: concurrent select-updates

[Nickolay <nitro@xxxxxxxxxxx>]

Kevin McConnell wrote:
> > CREATE OR REPLACE FUNCTION public.getmsg() RETURNS integer LANGUAGE plpgsql
> > AS $function$
> > declare
> >       rec record;
> > begin
> >       for rec in select id from msg where busy =alse order by id loop
> >               update msg set busy =rue where id = rec.id and busy = false;
> >               if found then
> >                       return rec.id;
> >               end if;
> >       end loop;
> >       return -1;
> > end;
> > $function$
> >     
>
> I think you could also do something roughly similar in a statement by
> using a RETURNING clause on the update, such as:
>
>   update msg set busy =rue where id = (select min(id) from msg where
> busy =alse) returning *;
>
> Cheers,
> Kevin
>   

Thank you guys! But what's min(id) for? Is it neccessary? Is there any 
chance I can replace min(id) to LIMIT 1?

Best regards, Nick.

--
Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-general