Defining Item Sets

An item set is composed of two or more data items in a COBOL record that contain identical information but that have been identified to Relativity as a set of redundant data items. Redundant data items include situations such as where one data item is identical to the first characters of another data item. One place where redundant data items are defined is in keys, where different keys provide different look-up capabilities in a file. Using Relativity, an item set becomes one data item in a relational database table.

Identifying redundant data items as an item set provides two advantages to Relativity:

• The Relativity DBMS is more likely to be able to choose an efficient index for accessing the data.
• When writing data with SQL UPDATE or INSERT statements, the redundant data will be maintained consistently by deriving its value from a single column value.

Item sets are maintained in the Properties pane for items pertaining to a set.