Re: PostgreSQL transaction locking problem

"Jeff Martin" <jeff@dgjc.org> writes:
> LOCK TABLE Test IN EXCLUSIVE MODE;

> /* This function should be able to operate concurrently BUT CANNOT */

How you figure that?  EXCLUSIVE lock is clearly documented to be
self-conflicting; so only one process can hold it at a time.  See
http://www.ca.postgresql.org/users-lounge/docs/7.1/postgres/locking-tables.html

If concurrency is important I'd suggest generating your ID values using
a sequence generator, rather than trying to build your own
implementation.

            regards, tom lane