Rebalancing partitions

You can rebalance partitions while reorganizing a table space. BMC AMI Reorg redistributes the rows and adjusts the limit keys across partitions.

Partition rebalancing occurs during the reorganization in one of following ways (listed in order of precedence):

General partition rebalancing considerations

The following considerations apply to all partition rebalancing methods:

• The value of the FASTSWITCH parameter must be YES. If the value is NO, BMC AMI Reorg issues a message and terminates.
• BMC AMI Reorg ignores any rebalance specification for nonpartitioned table spaces and for index reorganizations.
• BMC AMI Reorg invokes DSNUTILB when any of the following conditions exists:
  • A base table space contains LOB columns.
  • You also specify AUX to reorganize both the base table space and its LOB table space in a single invocation. 
  • The table space has ROTATED partitions.

  • The table space does not contain a partitioning index.

    Important

    (PTF BQU0252 applied) Do not use the REBALANCE option if you are reorganizing an XML table space or a table space containing an XML column. 

• You cannot rebalance table spaces that have a limit key that contains a floating-point column.
• The reorganization terminates if you request partition rebalancing and the number of duplicate keys will result in an empty partition. BMC AMI Reorg cannot accurately determine an appropriate limit key in this case.
• BMC AMI Reorg issues a message and does not rebalance partitions if it determines that the number of rows is too small to rebalance.

• You can have BMC AMI Reorg write out rebalancing information by specifying DD statements as follows:

  • Specify DD PARTSDDL to have BMC AMI Reorg write out DDL that you can use to create the table space, tables, and indexes that you are reorganizing.
  • Specify DD REPBLDAL to have BMC AMI Reorg out the ALTER statements for the object that you are reorganizing. These ALTER statements reflect the new keys following the rebalance operation.

  If you do not include one or both of these DD statements for a rebalancing reorganization, BMC AMI Reorg issues a warning message but continues the reorganization and rebalance operation.

CONSIDERATIONS

 The following considerations apply specifically to REBALANCE and DDLIN specifications:

• The reorganization terminates if your DDLIN contains a limit key ALTER operation that would result in discard processing. No discard processing occurs.
• If you specify both REBALANCE and AUX (using the BMC AMI LOBMaster product), BMC AMI Reorg invokes DSNUTILB.
• The reorganization terminates if you specify either the REBALANCE or DDLIN option and any of the following conditions exist:
  • You are running BMC AMI Reorg under the BMC AMI Utility Manager product.
  • You specify the DISCARD or MASSDELETE option.
  • You specify REBALANCE and the table space has a pending ALTER Limitkey.