Adding a Default Operator Class to the Access Method

Every access method must have at least one operator class so that the query optimizer knows which strategy and support functions apply to the index.

You assign a default operator class so that the database server can locate the strategy and support functions for an index if the CREATE INDEX statement does not specify them. To add an operator-class name as the default for the access method, set the am_defopclass purpose value in the sysams system catalog table. The following example shows how to set the am_defopclass purpose value:

ALTER ACCESS_METHOD my_virtual
   ADD AM_DEFOPCLASS = 'special_operators'

For more information, see ALTER ACCESS_METHOD (+). For more information about operator classes, as well as strategy and support functions, refer to IBM Informix: User-Defined Routines and Data Types Developer's Guide.