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® 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.
Data manipulation
Smart large objects
Creating a smart large object
Choosing storage characteristics
After initializing an LO-specification structure, you need to ensure that this structure contains the appropriate values for the storage characteristics you want the smart large object to have.

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 overview
    - Data manipulation
      - Numeric data types
        This section describes these numeric data types and the functions that the DataBlade® API supports to process numeric data.
      - Date and time data types
        This section describes the date and time data types and the functions that the DataBlade® API supports to process date and time data.
      - Complex data types
        This section describes the complex data types and the functions that the DataBlade® API supports to process collection and row-type data.
      - Smart large objects
        Smart large objects
        Storing a smart large object in a database
        To store a smart large object in a database, you must save its LO handle in a column. This section describes the valid data types to hold an LO handle and how to access a smart large object.
        The smart-large-object interface
        The smart-large-object interface contains a set of functions and data types to provide access to smart large objects.
        Creating a smart large object
        Obtain the LO-specification structure
        Before you create a smart large object, obtain a valid LO-specification structure to hold its storage characteristics.
        Choosing storage characteristics
        After initializing an LO-specification structure, you need to ensure that this structure contains the appropriate values for the storage characteristics you want the smart large object to have.
        Obtaining storage characteristics
        For most smart large objects, all you need to do is obtain the system-specified storage characteristics. When you obtain these storage characteristics for a smart large object, you can specify a location for it and override system-specified attributes.
        Storage-characteristics hierarchy
        HCL Informix® uses the storage-characteristics hierarchy to obtain the storage characteristics for a new smart large object.
        Initialize an LO handle and an LO file descriptor
        Write data to a smart large object
        To write data to the sbspace of a smart large object, use either the mi_lo_write() function or the mi_lo_writewithseek() function.
        Storing an LO handle
        The INSERT or UPDATE statement can store the LO handle of a smart large object into the CLOB, BLOB, or opaque-type column.
        Free resources
        When you create a smart large object, you might need to free resources of the LO-specification structure and the LO handle. After you store the new smart large object in the database, free any resources you no longer need.
        Sample code to create a new smart large object
        Accessing a smart large object
        Modify a smart large object
        After you have an LO file descriptor for an open smart large object, you can modify the smart large object by updating the smart large object or by altering some storage characteristics of the smart large object.
        Obtaining status information for a smart large object
        Delete a smart large object
        Convert a smart large object to a file or buffer
        The DataBlade® API provides support for the conversion of a smart large object to or from either an operating-system file or a user-defined buffer.
        Convert an LO handle between binary and text
        The DataBlade® API library provides functions that convert between the binary (internal) representation of an LO handle and its text (string) representation.
        Transfer an LO handle between computers (Server)
        For an LO handle to be portable when transferred across different computer architectures, the DataBlade® API provides functions to handle type alignment and byte order.
        Using byte-range locking
        By default, the database server uses whole lock-all locks when it needs to lock a smart large object. Lock-all locks are an all or nothing lock; that is, they lock the entire smart large object.
        Pass a NULL connection (Server)
        Many functions in the smart-large-object interface take a connection descriptor as a parameter. However, many of the functions also accept a NULL-valued pointer as a connection descriptor.
    - Database access
    - Create user-defined routines
    - Appendix
      This section contains additional reference information.
  - 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.

Choosing storage characteristics

After initializing an LO-specification structure, you need to ensure that this structure contains the appropriate values for the storage characteristics you want the smart large object to have.

About this task

Then you pass this LO-specification structure to one of the smart-large-object creation functions (Smart-large-object creation functions) so that the smart-large-object optimizer can obtain the storage characteristics to use for the new smart large object.

To choose storage characteristics for a new smart large object:

Procedure

Use the system-specified storage characteristics as a basis for obtaining the storage characteristics of a smart large object.
The system-specified storage characteristics are the default storage characteristics for a smart large object.
Customize the storage characteristics.
You can override the system-specified storage characteristics with one of the following levels of the storage-characteristics hierarchy:
- Storage characteristics defined for a particular CLOB or BLOB column in which you want to store the smart large object
  Storage characteristics that are unique to a particular CLOB or BLOB column are called column-level storage characteristics.
- User-specified storage characteristics.
  Special storage characteristics that you define for this smart large object only are called user-specified storage characteristics.

Results

Important: For most applications, use the system-specified values for the disk-storage information. Most DataBlade® API modules need to ensure correct storage characteristics only for an sbspace name (the location of the smart large object) and for the smart-large-object attributes.