REDEFINE

REORG PLUS can redefine both user-defined (VCAT-defined) data sets and data sets that are defined in Db2 storage groups (STOGROUP-defined).

Additional considerations

Note the following additional information about the REDEFINE option:

• When the following conditions exist, you must specify REDEFINE YES:
  • Before the reorganization, an ALTER changed the compression attribute of a participating index.
  • The DSVCI system parameter is set to YES, indicating that the control interval (CI) size is variable.
• If you are reorganizing a large number of partitions, consider specifying REDEFINE NO. This value minimizes the time that REORG PLUS requires to delete and redefine the existing VSAM data sets for the table space or indexes.
• If you do not specify SHRLEVEL REFERENCE or SHRLEVEL CHANGE, REORG PLUS does not redefine nonpartitioned indexes when performing a partial reorganization.

• When you specify a REXX exit name on the DSRSEXIT command or installation option, REORG PLUS calls the exit before performing DELETE/DEFINE processing for each Db2 VSAM component that it is going to define.

  In addition to the applications described in this section, you can use the DSRSEXIT user exit to change REDEFINE YES to REDEFINE NO for a specific object. For more information, see DSRSEXIT and Using-DSRSEXIT-to-manage-VSAM-data-set-redefinition.

Specifying the default

You can specify the default for the REDEFINE command option in your installation options module by using the REDEFINE installation option. REORG PLUS was shipped with a default value of YES for this option. The command option overrides the default that is in the installation options module.

YES

For SHRLEVEL NONE or SHRLEVEL REFERENCE UNLOADONLY, REORG PLUS deletes and redefines the VSAM data sets for the space before reloading it. For SHRLEVEL REFERENCE or SHRLEVEL CHANGE, REORG PLUS deletes and defines the staging data sets.

VCAT considerations

For VCAT-defined objects, the following considerations apply:

• When you specify UNLOAD PAUSE, you still have the option of deleting and redefining VCAT-defined data sets.

• When you specify UNLOAD CONTINUE or UNLOAD RELOAD, the only way to delete and redefine VCAT-defined data sets as part of the reorganization is to use REDEFINE YES and provide the SYSIDCIN data set containing the necessary IDCAMS control statements. Otherwise, REORG PLUS treats the job as if you had specified REDEFINE NO.

  For specification guidelines and detailed information about the use of the SYSIDCIN data set, see SYSIDCIN-data-sets-in-REORG-PLUS.

Storage group considerations

For storage-group-defined objects, the following considerations apply:

• When you specify this option for storage-group-defined data sets, do not provide a SYSIDCIN data set.
• For a storage-group-defined table space or index, REORG PLUS uses the value in DSNZPARMs for the SMS DATACLAS if a value exists, as follows:
  • For a table space, REORG PLUS uses the value in SMSDCFL.
  • For an index, REORG PLUS uses the value in SMSDCIX.

• For a storage-group-defined table space or index, REORG PLUS attempts to reallocate the data set on the volume on which it currently resides if the volume is still defined in the storage group.

  The order in which REORG PLUS retrieves subsequent volumes from the storage group for the purposes of allocating VSAM data sets is not predictable. You can use the DSRSEXIT user exit to sort the volumes into a different sequence. For information about this exit, see DSRSEXIT and Using-DSRSEXIT-to-manage-VSAM-data-set-redefinition.

• The redefined table space data sets will have a CI size that corresponds with the page size of the assigned buffer pool if the value of your DSVCI system parameter is set to YES.

NO

The REDEFINE NO option tells REORG PLUS not to delete and redefine the existing VSAM data sets for the table space or indexes. REORG PLUS instead issues message BMC50391I, reuses the existing data sets, and resets the high-used RBA.

VCAT considerations

For VCAT-defined objects, REORG PLUS

• Extends to another data set, if needed, as long as that data set is already defined
• Does not define any additional data sets

If you specify REDEFINE NO with SHRLEVEL REFERENCE or SHRLEVEL CHANGE, you must preallocate the staging data sets before the reorganization for VCAT-defined objects.

Storage group considerations

For storage-group-defined objects, the following considerations apply:

• For SHRLEVEL REFERENCE or SHRLEVEL CHANGE, REORG PLUS creates any staging data sets that you do not preallocate, but reuses any staging data sets that you do preallocate.
• For multi-data-set objects, REORG PLUS extends to another data set if needed, and creates it if the data set does not exist. When the reorganization completes, REORG PLUS deletes any data set that it did not use.
• The CI size for any additional data sets that REORG PLUS creates is based on the value of your DSVCI Db2 system parameter and the page size that is defined in the table space that you are reorganizing.

When invoking DSNUTILB, REORG PLUS passes this option to the IBM Db2 REORG utility as REUSE.