Segment compression control

If the BMC DATA PACKER/IMS product is installed in the database that you are reorganizing, you can use the COMPRESS keyword to dynamically expand and compress segment data during the reorganization.

SDEPs are excluded because the REORGANIZE command does not process SDEP segments.

The COMPRESS keyword feature lets you change compression techniques or other DATA PACKER/IMS product parameters. For more information, see the DATA PACKER/IMS documentationor contact BMC DATA PACKER/IMS technical support.

The following values are available for the COMPRESS keyword:

  • COMPRESS=NO (the default) causes segment data to be left unchanged.
  • COMPRESS=YES causes compressed segment data to be expanded then recompressed.
  • COMPRESS=(segment name1, segment name2, ..., segment namen) causes only the segments which are listed by name to be expanded then recompressed.

Note

When COMPRESS=YES or COMPRESS=(segment name) is specified, the offline reorganization function automatically uses the keyword value SELECT_UOW=ALL to ensure that all segments are expanded and recompressed.

In the example in the following figure, IAREA defaults to ALL. The segments that have a compression exit specified in the DBD are expanded and recompressed.

Using the COMPRESS keyword with the REORGANIZE command

REORGANIZE DBD=dbdname,COMPRESS=YES

The following figure shows an example of using the COMPRESS keyword to selectively specify segment compression for specified area. segment1, segment4 and segment5 in area1 are expanded and recompressed only if these segments have a compression exit specified in the DBD. Any other (unspecified) segments that have a compression exit specified in the DBD remain unchanged.

Selectively specifying segments for compression with reorganize

REORGANIZE DBD=dbdname,IAREA=area1,
  COMPRESS=(segment1,segment4,segment5)


Related topic

Reorganization-of-a-DEDB


 

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