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Extending Informix®Beyond standard relational database objects, HCL Informix® can be extended to handle specialized data types, access methods, routines, and other objects. Informix® includes many built-in extensions that are fully integrated in the database server. Informix® also provides DataBlade® modules, which are packages of extended database objects for a particular purpose and that are installed separately from the database server. Alternatively, you can create your own user-defined objects for Informix®.
Creating extensionsYou can create user-defined data types, routines, access methods, and other database objects to suit your needs. You can use application programming interfaces to write user-defined routines and applications that access data in Informix® databases.
Virtual-Table Interface GuideThe Informix® Virtual-Table Interface Programmer's Guide explains how to create a primary access method with the Virtual-Table Interface (VTI) so that users have a single SQL interface to HCL Informix® tables and to data that does not conform to the storage scheme of HCL Informix®.
Purpose-function referenceThese topics describe the purpose functions that the access-method developer provides.
Purpose-function syntaxThe database server expects a particular prototype for each purpose function. As the access-method developer, you program the actions of a purpose function but must use the parameters and return values that the Virtual-Table Interface (VTI) prototypes specify.
The am_truncate purpose functionHCL Informix® provides built-in am_truncate purpose functions for its primary access methods that support TRUNCATE operations on columns of permanent and temporary tables. Informix® also provides a built-in am_truncate purpose function for its secondary access method for TRUNCATE operations on B-tree indexes.

The am_truncate purpose function

HCL Informix® provides built-in am_truncate purpose functions for its primary access methods that support TRUNCATE operations on columns of permanent and temporary tables. Informix also provides a built-in am_truncate purpose function for its secondary access method for TRUNCATE operations on B-tree indexes.

Usage

You must use the am_truncate() access method with the TRUNCATE statement to operate on virtual tables or on tables with virtual indexes. You use TRUNCATE to depopulate a local table and free the storage space that formerly held its data rows and B-tree structures.

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