SELECT FOR UPDATE

A lot of BDL programs use pessimistic locking in order to avoid several users editing the same rows at the same time.

DECLARE cc CURSOR FOR
SELECT ... FROM tab WHERE ... FOR UPDATE
OPEN cc
FETCH cc <-- lock is acquired
...
CLOSE cc <-- lock is released

In both Informix^® and Netezza^®, locks are released when closing the cursor or when the transaction ends.

Netezza does not support SELECT FOR UPDATE statements.

Solution

You must review the program logic if you use SELECT FOR UPDATE statements. Actually Netezza systems are designed for data warehouse applications, not for OLTP applications. In a DW context, concurrent data access is not required or a priority.