Re: Best practices: MERGE

> The "correct" solution, as far as I can tell, is to acquire a LOCK on
> the table IN SHARE MODE at the beginning of the transaction, but this
> has (at least for many applications) unacceptable performance
> characteristics.  Accepting that there is a slight risk of a race
> condition when *not* locking the table at the beginning of the
> transaction, what procedure minimizes this risk and recovers well from
> said race condition, should it occur?

IN SHARE MODE is not enough, you can get deadlocks.  You require IN 
SHARE ROW EXCLUSIVE MODE.  other than that, it's a sucky solution 
because it breaks concurrency.  In pgsql 8, you can do it using pl/pgsql 
exception handling.

Chris