>>-CREATE OPCLASS--opclass--FOR--sec_acc_method----------------->
 
                  .-,--------------------------.
                  V                            |
>--STRATEGIES--(----| Strategy Specification |-+--)------------->
 
               .-,----------------.
               V                  |
>--SUPPORT--(----support_function-+--)-------------------------><
 

An operator class is the set of operators that support a secondary-access method for query optimization and building the index. A secondary-access method (sometimes referred to as an index access method) is a set of database server functions that build, access, and manipulate an index structure such as a B-tree, R-tree, or an index structure that a DataBlade module provides.

The database server provides the B-tree and R-tree secondary-access methods. For more information on the btree secondary-access method, see Default Operator Classes.

Define a new operator class when you want one of the following:

• An index to use a different order for the data than the sequence that the default operator class provides
• A set of operators that is different from any existing operator classes that are associated with a particular secondary-access method

You must have the Resource privilege or be the DBA to create an operator class. The actual name of an operator class is an SQL identifier. When you create an operator class, theopclass name must be unique within the database.

When you create an operator class in an ANSI-compliant database, the owner.opclass combination must be unique within the database. The owner name is case sensitive. If you do not put quotes around the owner name (or else set the ANSIOWNER environment variable), the name of the operator-class owner is stored in uppercase letters.

The following CREATE OPCLASS statement creates a new operator class called abs_btree_ops for the btree secondary-access method:

CREATE OPCLASS abs_btree_ops FOR btree
   STRATEGIES (abs_lt, abs_lte, abs_eq, abs_gte, abs_gt)
   SUPPORT (abs_cmp)

An operator class has two kinds of operator-class functions:

• Strategy functions

  Specify strategy functions of an operator class in the STRATEGY clause of the CREATE OPCLASS statement. In the preceding CREATE OPCLASS code example, the abs_btree_ops operator class has five strategy functions.

• Support functions

  Specify support functions of an operator class in the SUPPORT clause. In the preceding CREATE OPCLASS code example, the abs_btree_ops operator class has one support function.