Using Alternative Index Components

Alternative IOA indexes can be created for Active, Migration, and History User files, in addition to the corresponding regular IOA indexes.

With the ability to use alternative indexes, you can

• change native order of report entries in report list
• increase performance of report list requests

Control-D automatically chooses which index - primary or alternative - will be used for best performance for report list building under IOA online or Control‑D/Page On Demand (POD).

Control-D automatically chooses the primary index if the SHOW RULES parameter is set to YES on the Show Options window of the User Reports Entry Panel.

An alternative index definition specifies the structure of an alternative index record, the first part of which is an index key. Each field in the index key corresponds to one of the predefined fields from a VSA user record, or part of such a field. When a user file is scanned by an alternative index, index records are retrieved and checked against selection criteria, after which the correspondent user records are read. Alternative indexes provide retrieval of a smaller number of index records and thus requires fewer user records to be read to create the same report list.

To use alternative indexes, Alternative Index Components of corresponding User Files should be created. An Alternative Index Component is an IOA AM file, which contains Alternative Index records in the same way that the primary Index component of a User file contains primary Index records.

Note: The Report list SORT option does not work for Control-D/Web Access users if alternative indexes are implemented when WD3368 is activated.