Enables or disables carry-over lock optimization. Carry-over
    locks are enabled by default.

    While attached to the database, a process can have some active
    locks (locks attached to the database) and some carry-over
    locks (locks requested in earlier transactions that have not
    been demoted). If a transaction needs a lock it has currently
    marked as carry-over, it can reuse the lock by changing it to an
    active lock. The same lock can go from active to carry-over to
    active multiple times without paying the cost of lock request and
    demotion. This results in a substantial reduction in the number
    of lock requests if a process accesses the same set of areas
    repeatedly.

    As part of the carry-over lock optimization, a NOWAIT transaction
    requests, acquires, and holds a NOWAIT lock. This signals other
    processes accessing the database that a NOWAIT transaction exists
    and causes Oracle Rdb to release all carry-over locks. If NOWAIT
    transactions are noticeably slow in executing, you can specify
    CARRY OVER LOCKS ARE DISABLED with the CHANGE DATABASE or DEFINE
    DATABASE statement.

    This feature is available as an online database modification.