Operator class

The functions that operate on index keys of a particular data type make up an operator class.

The operator class has two types of functions:
  • Strategy functions, which are operators that appear in SQL statements For example, the function equal(column, constant) or the operator expression column = constant appears in the WHERE clause of an SQL query.
  • Support functions that the access method calls For example, the function compare(column, constant) might return a value that indicates whether each index key is less than, equal to, or greater than the specified constant.

The unique operator-class name provides a way to associate different kinds of operators with different secondary access methods.

You designate a default operator class for the access method. If a suitable operator class exists in the database server, you can assign it as the default. If not, you program and register your own strategy and support functions and then register an operator class.

For more information about operator classes, strategy functions, and support functions, see the Informix® User-Defined Routines and Data Types Developer's Guide.