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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.
Descriptor function reference
Accessor functionsThe Virtual-Index Interface (VII) library contains functions that primarily access selected fields from the various descriptors.
The mi_tab_unique() accessor functionThe mi_tab_unique() function determines if a CREATE INDEX statement specifies that the index contains only unique keys.

The mi_tab_unique() accessor function

The mi_tab_unique() function determines if a CREATE INDEX statement specifies that the index contains only unique keys.

Syntax

mi_boolean mi_tab_unique(MI_AM_TABLE_DESC *tableDesc)

tableDesc: Points to the index descriptor.

Usage

The access method can call this function from the am_create or am_insert purpose function. As the access method builds an index, it checks for unique key values if the mi_tab_unique() function returns MI_TRUE.

Return values

MI_TRUE: Indicates that the secondary access method must enforce unique keys for this index.
MI_FALSE: Indicates that the secondary access method should not enforce unique keys for this index.

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