Once you use the RMU Open command to open a database, the
    database remains open and mapped until you close it explicitly
    with an RMU Close command and all users have exited the database
    with the SQL DISCONNECT or EXIT statements. If you do not issue
    the RMU Open command, the first user to attach to the database
    incurs the cost of implicitly opening it and the last user to
    detach from the database incurs the cost of implicitly closing
    it.

    The effect of the RMU Open command depends on whether you have
    specified the OPEN IS AUTOMATIC or OPEN IS MANUAL clause to the
    SQL ALTER DATABASE statement, as follows:

    o  OPEN IS AUTOMATIC

       If you have specified automatic opening for your database,
       users can invoke the database at any time without first
       issuing an RMU Open command. (Although as mentioned above,
       it is more efficient to explicitly open the database with an
       RMU Open command and close it with an RMU Close command.)

    o  OPEN IS MANUAL

       If you have specified manual opening for your database, the
       RMU Open command must be issued before users can invoke the
       database.

    If you modify the database attribute from OPEN IS AUTOMATIC
    to OPEN IS MANUAL, the modification takes effect only after
    all users have detached from the database. (You can issue the
    RMU/CLOSE/ABORT=FORCEX command to force all users to detach.)
    Then, you must issue the RMU Open command before users can invoke
    the database.

    If you modify the database attribute from OPEN IS MANUAL to OPEN
    IS AUTOMATIC, users can invoke the database at their discretion.
    You do not have to issue the RMU Open command. However, if a
    user has already opened the database manually when you make this
    change to the database attribute, the modification takes effect
    only after you manually close the database by issuing the RMU
    Close command.

    See the Oracle Rdb Guide to Database Maintenance for information
    to help you decide whether to set your database attribute to
    automatic or manual opening.

    When you create a database, you have a choice of how to set up
    buffers for database pages. You can choose either local or global
    buffering. Global buffers can provide better system performance.
    See the Oracle Rdb7 Guide to Database Performance and Tuning for
    more information on setting the number of global buffers for your
    system.