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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 extensions
You 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.
R-Tree Index User's Guide
The Informix® R-Tree Index User's Guide describes the HCL Informix R-tree secondary access method and how to access and use its components.
Develop DataBlade® modules that use the R-tree secondary access method
Decide whether to use the R-tree access method

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.
- Informix® extensions and DataBlade® modules
  These topics describe how to use built-in database extensions and separately installed DataBlade® modules.
- Creating extensions
  You 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.
  - DataBlade® API Programmer's Guide
    The Informix® DataBlade® API Programmer's Guide describes information about the DataBlade API, the C-language application programming interface (API) provided with HCL Informix.
  - DataBlade® API Function Reference
    The Informix® DataBlade® API Function Reference describes the DataBlade API functions and the subset of Informix ESQL/C functions that the DataBlade API supports.
  - DataBlade® Developers Kit
    The DataBlade® Developers Kit (DBDK) guides contain information about the tools you can use to develop and package DataBlade modules, which extend the functionality of HCL Informix® databases.
  - J/Foundation Developer's Guide
    The J/Foundation Developer's Guide describes how to write user-defined routines (UDRs) in the Java™ programming language for Informix®.
  - R-Tree Index User's Guide
    The Informix® R-Tree Index User's Guide describes the HCL Informix R-tree secondary access method and how to access and use its components.
  - User-Defined Routines and Data Types Developer's Guide
    The Informix® User-Defined Routines and Data Types Developer's Guide describes how to define new data types and enable user-defined routines (UDRs) to extend HCL Informix.
  - Virtual-Table Interface Guide
    The 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.
  - Virtual-Index Interface Guide
    The 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.

Decide whether to use the R-tree access method

The R-tree secondary access method is specifically designed to index data with the following two special properties:

The data is multidimensional.
On a given dimension, a data object spans some width. That is, it corresponds to an interval or range, not a point.

Examples of these types of data include:

Two-dimensional spatial objects, such as points, lines, and polygons
Geographic mapping information, defined in terms of latitude and longitude, that includes pointlike objects, such as cities; linelike objects, such as roads and rivers; and regionlike objects, such as counties, states, and land masses
Video or audio clips, each with a start and stop time
If you create a time range user-defined data type, you can search for overlapping clips more efficiently with an R-tree index than with a B-tree index.
Color information that includes hue, brightness, and saturation
Multidimensional views of standard relational quantitative data, such as age, salary, sales commission, hire date, and so on

An R-tree index works on data with only one of these properties (multidimensional points or ranges along a single dimension) but data corresponding to points on a single dimension is better indexed with a B-tree index.

Unlike other data structures, such as a grid-file and a quad-tree, the R-tree access method does not require that data values be in a known bounded area.

If you are developing a DataBlade® module that includes a user-defined data type of a multidimensional or interval nature, you might want to use the R-tree access method to index columns of this data type.

The type of data most suited to B-tree indexes (the other indexing method included in HCL Informix®) is ordered numeric values in one dimension. Do not use B-tree indexes to index range or interval data. The following types of data are suited to being indexed with the B-tree access method and not the R-tree access method:

Numerical data, such as employee IDs
Character data, such as last names and product names

After you decide to use the R-tree access method to index a user-defined data type, you must create a new operator class. Creating a new operator class describes this process. The next section describes issues you should be aware of when you design the user-defined data type.