Re: SELECT ... FOR UPDATE

On Wed, 28 Mar 2001, Marcos Minshew wrote:

> I am interested in using the SELECT ... FOR UPDATE feature but it doesn't
> work quite the way I had hoped. If there is a better/different way of doing
> this please enlighten me.
>
> If I issue:
>
> BEGIN;
> SELECT * FROM atable WHERE atable.key = 10 FOR UPDDATE;
>
> in one session and then issue the same commands from a 2nd session, the 2nd
> session simply waits until the 1st session issues COMMIT or ROLLBACK. While
> the 2nd session is waiting I am, apparently locked out. What I would like
> is for the 2nd session to determine if the lock can be obtained and if not,
> offer the user a choice of waiting or escaping from the SELECT. Is this
> possible?
>
> Using 7.0.3

(I actually almost wrote an email asking this same question)

Has the documentation been updated recently or something I can find it
elsewhere (ie, not pg manual)? I think (maybe) I am not the only person
confused by documentation for LOCK and MVCC. "lack of detail / examples"
would probably say it best...

Thanks,
-Cedar