Syntax options:

    LOCKING IS ROW LEVEL | LOCKING IS PAGE LEVEL

    Specifies page-level or row-level locking as the default for the
    database. This clause provides an alternative to requesting locks
    on records. You can override the database default lock level
    at the storage area level. The default is ROW LEVEL, which is
    compatible with previous versions of Oracle Rdb.

    When many records are accessed in the same area and on the same
    page, the LOCKING IS PAGE LEVEL clause reduces the number of lock
    operations perfomed to process a transaction; however, this is at
    the expense of reduced concurrency. Transactions that benefit
    most with page-level locking are of short duration and also
    access several database records on the same page.

    Use the LOCKING IS ROW LEVEL clause if transactions are long in
    duration and lock many rows.

    The LOCKING IS PAGE LEVEL clause causes fewer blocking ASTs
    and provides better response time and utilization of system
    resources. However, there is a higher contention for pages and
    increased potential for deadlocks and long transactions may use
    excessive locks.

    Page-level locking is never applied to RDB$SYSTEM or the DEFAULT
    storage area, either implicitly or explicitly, because the lock
    protocol can stall metadata users.

    You cannot specify page-level locking on single-file databases.