Selecting the SDEP processing method

If the input database has an SDEP segment defined, you must indicate how these segments are to be processed. Multiple methods are available for processing SDEP segments during execution of the change function. The method is determined by the SDEP_PROCESS keyword:

  • SDEP_PROCESS=LOGICAL causes SDEP segments to be processed with the root segment that owns them. The SDEP segments in each output area are physically reordered into the same sequence as the parent root segments. The SDEP segments retain the same logical order (entry sequence) within each database record. If you are running IMS version 6.1 or higher, all SDEP segments are timestamped. If you do not want the SDEP segments to be timestamped, specify the SDEP_PROCESS=V5COMP value described on following figure.

    Warning

    If your application relies on the marker segment concept, do not use SDEP_PROCESS=LOGICAL.

  • SDEP_PROCESS=PHYSICAL causes SDEP segments to be processed in the physical sequence in which they appear in the input areas. SDEP segments are inserted into the output areas in the same relative physical location, which fully supports the marker segment concept. They also retain the same logical order (entry sequence) within each database record, including the same cycle count and timestamp.

    Note

    The following restrictions and considerations apply when SDEP_PROCESS=PHYSICAL is specified on the CHANGE command:

    • You cannot reduce the CI size of the area; however, you can increase the CI size.
    • You cannot modify the compression parameters for the SDEP segment.
    • You cannot specify the OUTPUT subcommand for the SDEP segment.
    • You cannot modify the randomization parameters such that root segments will be randomized to a different area.
    • SDEP pointer errors will not be detected. Consequently, any SDEP errors will not be applied to the error detection count value that you specify on the ERROR_THRESHOLD keyword.

  • SDEP_PROCESS=PHYSICAL causes SDEP segments to be processed in the physical sequence in which they appear in the input areas. SDEP segments are inserted into the output areas in the same relative physical location, which fully supports the marker segment concept. They also retain the same logical order (entry sequence) within each database record, including the same cycle count and timestamp.

    Warning

    If your application relies on the marker segment concept, do not use SDEP_PROCESS=V5COMP.

  • SDEP_PROCESS=NONE causes SDEP segments in the input areas to be ignored;these segments are not placed in the output areas. If SDEP segment types are detected in the input area, a warning message is generated to indicate that SDEP segments will be removed.

    The following figure shows an example of the SDEP_PROCESS keyword with the CHANGE command.

    CHANGE DBD=dbdname,SDEP_PROCESS=PHYSICAL

Related topic

Unloading-and-Reloading-a-DEDB

 

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