Hi Lauri,
I have same problem with my application (accounting and warehouse)
Solution
I use CachedUpdates
Implement my own MyApplayUpdates in one short transacion
I try 3 times MyApplayUpdates, if deadlock then rollback
if I have 3 deadlocks then I show message to user to try again
This message never apear in last 6 months (6 user connected)
I hope this will help you.

> Hello!
>
> I have a table with products(id, name, count) and another table with
> sold_products(id, name, count, invoiceno.. etc). sold_products has a
> trigger that fires on table insertions. It updates the count of products
> in products table. Trigger looks like this:
> Update products p set p.count = p.count - sold_products.count where p.id
> = sold_products.id;
>
> This works until two different transactions try to insert to table1.
> Then a deadlock occurs.
>
> (When this first occurred i had a foreign key sold_products on name
> pointing to products name. The error message (before i dropped the fk)
> was that there was a foreign key violation [fk name] on insert. This was
> nonsense so id dropped the key and the message changed to 'deadlock'.)
>
> Currently i solved this by committing the transaction immidiately, but i
> do not like this (there was supposed to be other tables involved in the
> same transaction too).
>
> Can't the p.count be involved in transactions? I can vaguely understand
> what the problem is.. maybe a new function like pascals inc(value,
> count) would solve this?
>
> Or another approach to maintaining product amounts maybe?
>
>
> BR,
> Lauri