Extracting SDEP segments

FM/IMS allowed two possible methods to order extracted SDEP segments:

Reverse-retrieval order (default)

This method reverses the SDEPs order from their retrieval sequence. Loading SDEPs in this order restores their sequence under each root but does not restore the sequence as seen by the sequential scan utility.

Sample result as viewed in the database:

CUSTROOT  ..00000001 CUSTROOT SEGMENT
CUSDEPSG  .. 5TH SEGMENT INSERTED
CUSDEPSG  .. 4TH SEGMENT INSERTED
CUSDEPSG  .. 1ST SEGMENT INSERTED
CUSTROOT  ..00000010 CUSTROOT SEGMENT
CUSDEPSG  .. 6TH SEGMENT INSERTED
CUSDEPSG  .. 3RD SEGMENT INSERTED
CUSDEPSG  .. 2ND SEGMENT INSERTED

Sample result of the sequential scan utility:

2ND SEGMENT INSERTED
3RD SEGMENT INSERTED
6TH SEGMENT INSERTED
1ST SEGMENT INSERTED
4TH SEGMENT INSERTED
5TH SEGMENT INSERTED

SDEP Timestamp order

This method attempts to place the retrieved SDEP segments into their original insertion order by reading their timestamps with the POS DL/I call. The timestamps are written to the unload file with the SDEP segments. This method is more costly because of the POS call overhead, however, loading SDEPs in this order restores both their order under each root as well as the sequence as seen by the sequential scan utility.

Sample result as viewed in the database:

CUSTROOT  ..00000001 CUSTROOT SEGMENT
CUSDEPSG  .. 5TH SEGMENT INSERTED
CUSDEPSG  .. 4TH SEGMENT INSERTED
CUSDEPSG  .. 1ST SEGMENT INSERTED
CUSTROOT  ..00000010 CUSTROOT SEGMENT
CUSDEPSG  .. 6TH SEGMENT INSERTED
CUSDEPSG  .. 3RD SEGMENT INSERTED
CUSDEPSG  .. 2ND SEGMENT INSERTED

Sample result of the sequential scan utility:

1ST SEGMENT INSERTED
2ND SEGMENT INSERTED
3RD SEGMENT INSERTED
4TH SEGMENT INSERTED
5TH SEGMENT INSERTED
6TH SEGMENT INSERTED

To use this extract method, check the SDEP in timestamp order option on the Extract Entry panel when generating the extract JCL, or manually specify the SDEPTSO JCL option in the IXB function.