Changing the high key of a partition

You can change the high key of a partition to either increase or decrease the number of records the partition contains.

Recommendation: Prior to changing the high keys of partitions in your HALDB database, enable the HALDB reorganization number verification function. The HALDB reorganization number verification function protects the integrity of data when records are moved by a change in a high key or by database reorganizations.

To change the high key of a partition:

Procedure

  1. For all partitions that will be affected by the change to the high key, issue either the /DBRECOVERY DB partition_name command or the UPDATE DB NAME(partition_name) STOP(ACCESS) command.
  2. Unload all partitions that will be affected by the change to the high key.
  3. Change the high key definition for the partition by using either the HALDB Partition Definition utility (%DFSHALDB) or DBRC commands.
  4. Initialize all partitions that are affected by the change by running either of the following utilities:
    • HALDB Partition Data Set Initialization utility (DFSUPNT0)
    • Database Prereorganization utility (DFSURPR0)
  5. Reload all partitions that are affected by the change by using the output of step 2. The image copy needed flag is set for the data sets in the reloaded partitions.
  6. Create image copies of the data sets in the affected partitions. DBRC does not allow updates to the data after the image copy required flag is set and before the image copies have been recorded in the RECON data sets.
  7. Make the partitions available again by issuing either the /START DB partition_name command or the UPDATE DB NAME (partition_name) START(ACCESS) command.

An online IMS system is not aware of the changes to partition definitions in the RECON data set until one of the following events occurs:

  • A /START DB HALDB_Master OPEN command is issued.
  • An UPDATE DB NAME(HALDB_Master) START(ACCESS) OPTION(OPEN) command is issued.
  • A DL/I call causes an authorization call to DBRC for a partition affected by the change. The first DL/I call goes through HALDB partition selection again to select and authorize the correct partition.