Re: Locking vs. Exceptions

Hi,

The documentation says that function blocks with exceptions are far costlier
than without one.

So if I need to implement an INSTEAD OF trigger (after checking for unique
constraint violations) which way should I go ?

1. Get a table lock
2. Use 'Select ... For Update' (which could be used to lock only the desired
recordsets)
3. Use Exceptions

Any advice / experiences or even pointers would be helpful.

Thanks
Robins Tharakan

Robins wrote:
> Hi,
>
> The documentation says that function blocks with exceptions are far
> costlier than without one.
>

I recommend against using exceptions. There is a memory leak in the
exception handler that will cause headaches if it is called many times
in the transaction.

In plpgsql, I would use:

SELECT ... FOR UPDATE;
IF FOUND THEN
UPDATE ...;
ELSE
INSERT ...;
END IF;

If you have multiple transactions doing this process at the same time,
you'll need explicit locking of the table to avoid a race condition.

--
Benjamin Minshall <minshall(at)intellicon(dot)biz>
Senior Developer -- Intellicon, Inc.
http://www.intellicon.biz