DB groups

A DB group is a named collection of databases or DEDB areas. A DB group name can be specified in the /START, /STOP, /DBRECOVERY, and /RECOVER commands, instead of issuing these commands separately for each database or area.

Specifying a DB group name with these commands greatly reduces the number of times these commands must be issued. Use the DATAGROUP keyword to specify the DB group name.

DB groups can also include HALDB master and HALDB partition names. Be aware of the effects of a command issued using a DB group that has a HALDB master name and one or more of its partitions. See IMS Version 13 Database Administration for more information.

You can define as many DB groups as you want. Up to 32767 databases or areas can be in a group. A database or area can belong to more than one DB group and need not be registered in the RECON data set.

Recommendation: Use a database group whenever possible, even though a DBDS group can be used as a DB group. Processing a DBDS group as a DB group entails increased overhead.
DB groups are a form of a DBDS group, so they are stored in the RECON data set using the DBDS group record. The following commands affect the definition of a DB group:
  • INIT.DBDSGRP
  • CHANGE.DBDSGRP
  • DELETE.DBDSGRP
  • LIST.DBDSGRP
Parent topic: Considerations for a DBRC system