VMS Help  —  RMU72  Load  Database
    Loads data into the tables of the database.

    You can use the RMU Load command to:

    o  Perform the initial load of an Oracle Rdb database.

    o  Reload a table after performing a restructuring operation.

    o  Load an archival database.

    o  Move data from one database to another.

    o  Load security audit records from an OpenVMS security audit
       table into the database being audited, or into a different
       database than the one being audited.

    o  Load additional rows into an existing table. (However, note
       that it cannot be used to modify existing rows.)

    o  Import data into a database from an application that generates
       RMS files.

    You can load data using either of the following two methods:

    o  A single-process method

       This was the only method available prior to Oracle Rdb V7.0.
       The single process method uses one process to both read the
       input file and load the target table.

    o  A multiprocess method, also called a parallel load

       The parallel load method, which you specify with the Parallel
       qualifier, enables Oracle RMU to use your process to read
       the input file and use one or more executors (subprocesses
       or detached slave process, depending on additional factors)
       to load the data into the target table. This results in
       concurrent read and write operations, and in many cases,
       substantially improves the performance of the load operation.

    By default, Oracle RMU sets up a parallel load operation as
    follows:

    o  Your process serves as the load operation execution manager.

    o  Each storage area (partition) in the table being loaded is
       assigned an executor.

    o  Each executor is assigned four communications buffers.

       (You can override this default with the Buffer_Count option to
       the Parallel qualifier.)

    o  Each communications buffer holds the number of rows defined by
       the Row_Count qualifier.

    Once the executors and communications buffers are set up, the
    parallel load operation processes the input file as follows:

    1. Your process begins reading the input file and determines the
       target storage area for each row in the input file.

    2. Your process places each row in the communications buffer for
       the executor assigned to the data's target storage area.

    3. When an executor's first communications buffer becomes full,
       it begins loading the data into the target storage area.

    4. If your process has another portion of data ready for a given
       executor before that executor has completed loading its first
       buffer of data, your process places the next portion of data
       in the second communications buffer for that executor.

    5. Each executor, concurrent with each of the other executors,
       loads the data from its buffers.

    6. Your process continues reading, sorting, and assigning data to
       each executor (by placing it in that executor's communication
       buffer) until all the data from the input file has been
       sorted, assigned, and loaded.

    The Row_Count qualifier and Parallel qualifier (which provides
    the Executor_Count and Buffer_Count options) give you the ability
    to fine tune the Parallel load operation.

    See the Oracle Rdb Guide to Database Design and Definition for
    tips on optimizing the performance of the load operation.
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