Indexes are generated dynamically when a table is opened, based on information in the table definition for a primary Index or, in the Alternate Index definition, for an Alternate Index. In general, an Alternate Index is treated like any other table, although it contains no data of its own. Unless otherwise noted, documentation for table processing also applies to Alternate Indexes.
An Alternate Index is created using the CA or IA commands. An Alternate Index may be opened using the open commands OR or OW, or an IA command. When an Alternate Index is opened with an OR or OW command, the Data Table will also be opened if it is not already open. An IA command will only work if the Data Table is already open for read or open for write.
You may define more than one Alternate Index for a particular Data Table. Any changes made using an Alternate Index are made to the Data Table and will be reflected in all open Alternate Indexes based on that Data Table.
To control the user(s) or transactions that perform updates in a multi-user environment after opening of an Alternate Index for write, place a password in the LOCK-LATCH field when opening for write using either an OW or CN command. Only the update commands that have the same password in the LOCK-LATCH field are authorized to perform the update (see 9. LOCK-LATCH (8 bytes)).