Modifying databases

You can modify your database structure in a variety of ways using the reorganization utilities and other methods.

Over time, user requirements can change, necessitating changes in the database design. Or you might choose to use new or different options or features. Or perhaps you have simply found a more efficient way to structure the database.

When you modify your database, you often make more than a simple change to it. For example, you might need to add a segment type and a secondary index. This topic has procedures to guide you through making each type of change.

If you make more than one change at a time, refer to Changing the number of data set groups, which contains a series of flowcharts that, when used with the individual procedures in this topic, can guide you in making some types of multiple changes to the database.

Attention: If the DBD for an existing MSDB is changed, the header information (BHDR) might change, even though the database segments do not. In this case, the headers in the MSDBCPx data sets are invalid or the wrong length. A change in the MSDB headers causes message DFS2593I. If ABND=Y is specified in the MSDB PROCLIB member, ABENDU1012 is also issued. Correct this problem by using the MSDBLOAD option on a warm start or cold start to load the MSDBs from an MSDBINIT data set.