Re: [Gnumed-devel] layout managers

[Horst Herb]

On Sun, 25 Jul 2004 23:32, Karsten Hilbert wrote:
> - table trigger sends NOTIFY with patient ID attached
>   - no one emits NOTIFIES

The bit where this fails over is that NOTIFY cannot carry any parameters - at 
least not tile version 7.3, and I doubt this has changed.

Thus, the backend can send a NOTIFY that *a* patient has changed, but that 
mechanism won't tell you which one.

What you can do is construct a NOTIFY_PATID_1234 notice,
and whenever you intend to modify patient id 1234, you temporarily listen to 
exactly that message - but it somehow generates more backend traffic rather 
than saving it.

Hence, you can either lock a particular row as soon as you intend to edit it - 
which will prevent anybody else to edit it at the same time - or it gets 
very, very complicated.

That is, you'll have to do a "select for update" statement whenever you 
consider the ere *possibility* that a user interface element will change 
data.

Horst