Creating alternate indexes
An alternate index provides access to the records in a data set that uses more than one key. It accesses records in the same way as the prime index key of an indexed data set (KSDS).
When planning to use an alternate index, you must know:
- The type of data set (base cluster) with which the index will be associated
- Whether the keys will be unique or not unique
- Whether the index is to be password protected
- Some of the performance aspects of using alternate indexes
Because an alternate index is, in practice, a VSAM data set that contains pointers to the keys of a VSAM data set, you must define the alternate index and the alternate index path (the entity that establishes the relationship between the alternate index and the prime index). After you define an alternate index, make a catalog entry to establish the relationship (or path) between the alternate index and its base cluster. This path allows you to access the records of the base cluster through the alternate keys.
To use an alternate index, do these steps:
Example: entries for alternate indexes
Language Environment® Programming Reference (AIXBLD (COBOL only))