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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-Index Interface GuideThe Informix® Virtual-Index Interface Programmer's Guide explains how to create a secondary access method with the Virtual-Index Interface (VII) to extend the built-in indexing schemes of HCL Informix® typically with a DataBlade® module.
Design decisionsThese topics present the choices that you make to optimize the performance and flexibility of the access method that you can create with the virtual-index interface (VII).
Using FastPath

Using FastPath

The access method can use a DataBlade® API facility called FastPath to execute registered UDRs that are not in the same shared-object module as the access-method functions.

To use the FastPath facility, the access method completes the following general steps:

Obtains a routine identifier for the desired UDR.
Passes the routine identifier to the DataBlade API mi_func_desc_by_typeid() function, which returns the function descriptor.
Passes the function descriptor to the DataBlade API mi_routine_exec() function, which executes the function in a virtual processor.

For complete information about FastPath functions and the function descriptor (MI_FUNC_DESC), see the Informix® DataBlade API Programmer's Guide.

Important: A database server exception results if a parallelizable function attempts to execute a routine that is not parallelizable. Use mi_func_desc_by_typeid() and mi_routine_exec() from a parallelizable access method only if you can guarantee that these functions look up or execute a parallelizable routine.

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