Opaque (IDS)

An opaque type is a data type for which you must provide the following information to the database server:

• A data structure for how the data values are stored on disk
• Support functions to determine how to convert between the disk storage format and the user format for data entry and display
• Secondary access methods that determine how the index on this data type is built, used, and manipulated
• User functions that use the data type
• A system catalog entry to register the opaque type in the database

The internal structure of an opaque type is not visible to the database server and can only be accessed through user-defined routines. Definitions for opaque types are stored in the sysxtdtypes system catalog table. These SQL statements maintain the definitions of opaque types in the database:

• The CREATE OPAQUE TYPE statement registers a new opaque type in the database.
• The DROP TYPE statement removes a previously defined opaque type from the database.

For more information on the above-mentioned SQL statements, see the IBM Informix: Guide to SQL Syntax. For information on how to create opaque types and an example of an opaque type, see IBM Informix: User-Defined Routines and Data Types Developer's Guide.