Modifying Schema Entities › Record Modifications › Changing a Record's CALC Key

Changing a Record's CALC Key

Types of Changes

You can make the following changes to a record's CALC key:

• Replace one or more elements in the CALC key
• Add or remove elements in the CALC key
• Change the picture or usage of an element in the CALC key

What components are affected

Both the schema record definition and the data are affected. Subschemas and access modules that reference the record are also affected.

Steps to change the CALC key

To change the CALC key of a schema record where data has been loaded:

1. Add a new schema based on the original schema
2. Modify the record in the new schema specifying the new CALC key or any changes to fields currently participating in the record's CALC key
3. Validate the schema
4. Execute the RESTRUCTURE utility if any fields within the record's CALC key have had their definitions changed or any of the conditions discussed under "Considerations" apply
5. Create a new global subschema if applicable
6. Unload and reload the database
7. Complete the process by updating the original schema definition, regenerating subschemas, and altering affected access modules

Considerations

• If a field to be added to the CALC key does not exist in the record, add the field using RESTRUCTURE and initialize it before unloading and reloading the data. Initialize the field using restructure or a user-written program.

  Note: For information about adding a new record element, see 33.5.7, "Modifying Record Elements".

• If using UNLOAD and RELOAD (instead of REORG) to change a CALC key, the following additional considerations apply:
  • If the control length of the record is changing as a result of the change to the CALC key and the record is compressed or variable length, you must do one of the following:
    • Use RESTRUCTURE to alter the control length before unloading and reloading the data.
    • Unload and reload the data twice (using the old subschema on the first unload and the new subschema on the second)
  • UNLOAD/RELOAD clusters VIA records based on the CALC key defined in the subschema used to unload the data. Therefore, you need to do a second UNLOAD/RELOAD to properly cluster VIA records if the subschema used to unload the data describes the old CALC key.

    As an alternative, you can use the new subschema for unloading. This ensures that the new CALC key is used to determine target pages for both the CALC record and its associated VIA records. However, the new subschema can be used to unload data only if no other changes have been made to the record (such as the record's area, set pointers, etc.).

    In some cases, multiple changes can be accommodated by using an intermediate schema/subschema to unload the data. For example, to change the CALC key of a record and also move it to a new area, unload the data using a subschema that describes the record's new CALC key but old area. Reload the data using a subschema describing the new CALC key and the new area.