Managing member subset definitions

Member subsets can be created, altered, and dropped as required by using a set of management routines.

Member subsets are managed by using these routines:
  • Create a member subset: WLM_CREATE_MEMBER_SUBSET.
  • Alter a member subset: WLM_ALTER_MEMBER_SUBSET.
  • Drop a member subset: WLM_DROP_MEMBER_SUBSET.
A work load management license is not required to invoke these routines. To create, alter, or drop a member subset, you require DBADM, or WLMADM authority.

The member subset management routines are autonomous routines that run in their own transaction scope. Work that is performed by the routines is independent from the work that is performed by the invoking session. Transactional work that is executed by the routines is independent from the transactional work that is executed by the invoking session. When a routine successfully completes, the work is committed. If the routine fails, the work is rolled back. In either case, the invoking session's transaction is not affected. You cannot issue a roll back operation to undo the work that is performed by a member subset management routine. To undo the work, you must use the WLM_ALTER_MEMBER_SUBSET or WLM_DROP_MEMBER_SUBSET routine.

By default, creating a member subset catalog user-specified database alias on the Db2® data server. The WLM_ALTER_MEMBER_SUBSET routine can be used to disable an enabled member subset. Applications that attempt to connect to the database and are assigned to a disabled member subset receive an error message.

After creation of a member subset, it is enabled by default.

Members can be added to, altered or dropped from, an existing member subset by the WLM_ALTER_MEMBER_SUBSET management routine.

A database alias is managed by a member subset if it is cataloged by WLM_CREATE_MEMBER_SUBSET or WLM_ALTER_MEMBER_SUBSET. Database aliases that are managed by a member subset are uncataloged when that member subset is dropped, or when that member subset is altered to use a different database alias. Database aliases that are managed by a member subset cannot be uncataloged by the UNCATALOG DATABASE command or the sqleuncd API.

Database aliases that are not managed by a member subset are not modified by any member subset management routine and can be uncataloged by the UNCATALOG DATABASE command or the sqleuncd API.

Database aliases that are managed by a member subset are cataloged the first time that the database is activated after a restore, if they are not already cataloged.

These system catalog views can be queried to view the member subset definitions, corresponding attributes, and members included in a member subset:
  • Definition of a member subset: SYSCAT.MEMBERSUBSETS
  • Corresponding subset attributes: SYSCAT.MEMBERSUBSETATTRS
  • Corresponding subset attributes including the associated database alias: SYSCAT.MEMBERSUBSETMEMBERS.