Home
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.
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.
DataBlade® Developers Kit User's Guide
The HCL Informix® DataBlade® Developers Kit User's Guide describes how to use tools to develop and package DataBlade modules.
Design DataBlade® modules
This section describes the DataBlade® module SQL design issues.
Query processing
To develop a DataBlade® module, you need a general understanding of query processing and HCL Informix® SQL. You must also understand the execution environment inside your Informix database server ̵ the multithreading model, the collection of processes in which DataBlade module routines can execute, and concurrent access to database objects, transactions, and so on.
Access path selection
During query processing, your database server takes a nonprocedural query and produces a procedural plan for satisfying it; this process is called making an access path selection.
Unordered row processing

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.
    - DataBlade® Module Development Overview
      The HCL Informix® DataBlade® module overview serves as an overview of the HCL Informix DataBlade module development process.
    - DataBlade® Developers Kit User's Guide
      The HCL Informix® DataBlade® Developers Kit User's Guide describes how to use tools to develop and package DataBlade modules.
      - Getting started with DataBlade® module development
        This section provides an overview of DataBlade® module development and describes the resources and tools the HCL Informix® database server provides to facilitate development.
      - Design DataBlade® modules
        This section describes the DataBlade® module SQL design issues.
        Data model
        A data model is a high-level definition of a DataBlade® module: what objects it represents and what operations on those objects it provides.
        Data type design
        After you have designed a data model for your DataBlade® module, you can design its specifics, such as data types to best represent your DataBlade module objects.
        Query language interface
        The next component in DataBlade® module design is the query language interface.
        Query processing
        To develop a DataBlade® module, you need a general understanding of query processing and HCL Informix® SQL. You must also understand the execution environment inside your Informix database server ̵ the multithreading model, the collection of processes in which DataBlade module routines can execute, and concurrent access to database objects, transactions, and so on.
        Predicate evaluation
        An expression in the qualification of a query is a predicate.
        Grouping
        Use SQL to write queries that group results. Grouping is a powerful facility for summarizing data, particularly in combination with aggregates such as COUNT or SUM.
        Casts
        If your DataBlade® module defines types that are similar or comparable, consider defining casts between the types. You can also define casts from DataBlade module types to built-in types, and from data types in one DataBlade module to data types in another DataBlade module.
        Access path selection
        During query processing, your database server takes a nonprocedural query and produces a procedural plan for satisfying it; this process is called making an access path selection.
        Unordered row processing
        Secondary access methods
        A secondary access method is an index that allows queries to be evaluated more efficiently.
        Plan for transaction semantics
        The DataBlade® module code runs in SQL transactions. A transaction is a single, atomic, independent sequence of client/server interactions.
        Interoperability
        The interoperability of a DataBlade® module refers to how well that module works with your HCL Informix® database server and with other DataBlade modules.
      - Programming guidelines
        Use this section to help you when you write the design specification for your DataBlade® module.
      - Create DataBlade® objects by using BladeSmith
        Use BladeSmith to create DataBlade® modules.
      - Programming DataBlade® module routines in C
        This section contains information to help you edit and compile C language source code generated by DataBlade®.
      - Create ActiveX value objects
        This section describes how to use the to create ActiveX value objects. This section describes the use of C++ to implement opaque type support routines.
      - The ActiveX value objects
        This section provides information for client application developers who are using ActiveX value objects.
      - Programming DataBlade® modules in Java™
        This section contains information to help you edit and compile Java™ language source code generated by BladeSmith.
      - Debugging and testing DataBlade® modules on UNIX™
        This section describes how to debug and perform functional tests for DataBlade® modules written in C for Informix® on UNIX™.
      - Debugging and testing DataBlade® modules on Windows™
        This section describes how to debug and perform functional tests for DataBlade® modules written in C and C++ for Informix® on Windows™.
      - BladePack
        BladePack creates installation packages for DataBlade® modules and other software products.
      - Appendixes
        This section contains additional reference information.
    - DBDK InfoShelf
      The DataBlade® Developers Kit InfoShelf is designed to help you work with BladeSmith.
  - 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.

Unordered row processing

When you design a DataBlade® module, you cannot control how queries are executed. There is no guarantee that the routines in a query are called in any particular order. DataBlade® module routines are called during query processing to compute answers to queries. Do not hardcode query execution strategies. For example, an attempt to force an index scan or a sequential table scan reduces the number of choices available to the query optimizer and results in poor performance.

To ensure that your DataBlade® module does not conflict with the query processing engine, ask the following questions:

Do any routines require values to be delivered in some particular order? If so, the routines break a fundamental rule of relational database systems and must be changed.
Is it important for routines in a query to execute in some particular sequence? Again, the routines must be changed.