Re: Lock Detection (was: pg_dump failing on LinuxPPC)

Stu Coates <stu@StuCoates.com> writes:
> I come from an Oracle background where I can lock an item of data by
> performing a "SELECT FOR UPDATE" on the row.  This is also implemented
> in PostgreSQL.  A quite useful feature Oracle does have is the ability
> to add a "NOWAIT" clause to the end of the command which will cause an
> exception if the item of data already has a lock taken out on it.
> AFAIK, this is not implemented in PostgreSQL.  I did see a note that
> lock timeouts are not implemented, but if "NOWAIT" is added the
> application developer could implement/fudge timeouts him/herself.  Would
> this be relatively easy to add?

It'd be possible, but not particularly easy; anything that involves
changing parse/plan trees is tedious.  Moreover, I doubt that it'd be
especially useful given the lack of nested transactions in Postgres.
You'll have to make a lot better case than the above if you want to
get anyone excited about the idea.

            regards, tom lane