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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_param_exist() accessor functionThe mi_tab_param_exist() function retrieves the index-configuration parameters that are available for one of multiple indexes that consist of the same key columns.

The mi_tab_param_exist() accessor function

The mi_tab_param_exist() function retrieves the index-configuration parameters that are available for one of multiple indexes that consist of the same key columns.

Syntax

mi_string * mi_tab_param_exists(MI_AM_TABLE_DESC *tableDescr,
   mi_integer n)

tableDesc: Points to the index descriptor.
n: Specifies a particular index from among multiple indexes on equivalent columns.
The first CREATE INDEX statement for those columns creates index 0. To select that index, set n to 0. To select the second index created on the same columns, set n to 1.

Usage

To support multiple search schemes for the same set of columns, the VII enables the user to identify each search scheme with a set of keyword parameters. The user specifies these parameters in the CREATE INDEX statements for these indexes. The access method uses the related functions together to determine if CREATE INDEX statements specify new or duplicate keyword values.

Return values

The string lists keywords and their values from the amparam column of the sysindexes system catalog table for index n.

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