Determining How an Entity Should Be Stored › Graphic Conventions › Conventions for Representing Indexes

Conventions for Representing Indexes

To represent an index on the data structure diagram:

• Use a triangle to represent the index.
• Specify a name for the index.
• Identify the data element name(s) that are to be indexed.
• Specify whether duplicate indexed keys are allowed (blank) or not allowed (U).

Sample index representation

The following diagram shows the standard CA IDMS/DB notation for an index. The index allows the DBMS to access all EMPLOYEE entity occurrences in the database based on the last name/first name in ascending order. Duplicate last name/first name combinations are allowed.