Default Operator Classes

Each secondary-access method has a default operator class that is associated with it. By default, the CREATE INDEX statement associates the default operator class with an index.

For example, the following CREATE INDEX statement creates a B-tree index on the zipcode column and automatically associates the default B-tree operator class with this column: 
CREATE INDEX zip_ix ON customer(zipcode)
For each of the secondary-access methods that Informix® provides, it provides a default operator class, as follows:
  • The default B-tree operator class is a built-in operator class.

    The database server implements the operator-class functions for this operator class and registers it as btree_ops in the system catalog tables of a database.

  • The default R-tree operator class is a registered operator class.

    The database server registers this operator class as rtree_ops in the system catalog tables. The database server does not implement the operator-class functions for the default R-tree operator class.

Important: To use an R-tree index, you must install a spatial DataBlade® module, such as a third-party DataBlade® module that implements the R-tree index. These implement the R-tree operator-class functions.

DataBlade® modules can provide other types of secondary-access methods. If a DataBlade® module provides a secondary-access method, it might also provide a default operator class. For more information, refer to your DataBlade® module user's guide.