Welcome
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 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.
Programmer's Guide
The HCL® Informix® DataBlade® API Programmer's Guide describes information about the , the C-language application programming interface (API) provided with HCL Informix.
Create user-defined routines
Manage memory
A C user-defined routine (UDR) has access to shared memory for dynamic allocations and stack memory for routine arguments (including the MI_FPARAM structure), local stack variables, and return values.
Manage shared memory
Manage user memory
A C UDR allocates user memory from the database server shared memory. It is accessed by address. The provides memory-management functions to allocate user memory dynamically. These functions return a pointer to the address of the allocated memory and subsequent operations are performed on that pointer.
Manage the memory duration
The current memory duration is the memory duration that applies when the mi_alloc() or mi_zalloc() function allocates memory. These functions do not specify a memory duration for their allocation. Instead, they use the current memory duration for the memory they allocate.
The current memory duration
Many of the constructor functions assign the current memory duration to the data type structures that they allocate.

HCL Informix® V15.0.0 documentation
Welcome to the documentation for HCL Informix® 15.0.0 and related client tools and products.
Product overview
HCL Informix® is a fast and scalable database server that manages traditional relational, object-relational, and dimensional databases. Its small footprint and self-managing capabilities are suited to embedded data-management solutions.
Installing
These topics describe how to install HCL Informix® database servers, client products, and modules.
Administering
In addition to administering the database server, you can tune performance, replicate data, and archive data.
Migrating and upgrading
You can upgrade to the 15.0.0 release of HCL Informix® or migrate from other database servers to Informix. Upgrading is an in-place migration method that uses your existing hardware and operating system software. Some changes to the Informix database server can affect upgrading from a previous release.
Client APIs and tools
You can use the HCL Informix® implementation of client APIs to develop applications for Informix database servers.
Embedding Informix®
When you embed HCL Informix®, you can use enterprise-class high-availability and high performance with embeddability features such as easy programmability, a small disk and memory footprint, and silent deployment.
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 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 modules
  These topics describe how to use built-in database extensions and separately installed 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.
  - Programmer's Guide
    The HCL® Informix® DataBlade® API Programmer's Guide describes information about the , the C-language application programming interface (API) provided with HCL Informix.
    - overview
    - Data manipulation
    - Database access
    - Create user-defined routines
      - Develop a user-defined routine
        A C user-defined routine (UDR) is a UDR that is written in the C language and uses the server-side implementation of the to communicate with the database server. C UDRs (functions and procedures) are implemented as C-language functions. modules often include C UDRs that are made available for use by registering them in the database.
      - Write a user-defined routine
        This section outlines some implementation issues for C user-defined routines (UDRs). This section also describes the specific features and tasks of a C UDR.
      - Manage memory
        A C user-defined routine (UDR) has access to shared memory for dynamic allocations and stack memory for routine arguments (including the MI_FPARAM structure), local stack variables, and return values.
        Shared memory
        When a C UDR executes in a virtual processor (VP), it allocates memory from the shared memory of the database server.
        Manage shared memory
        Manage user memory
        A C UDR allocates user memory from the database server shared memory. It is accessed by address. The provides memory-management functions to allocate user memory dynamically. These functions return a pointer to the address of the allocated memory and subsequent operations are performed on that pointer.
        Allocate user memory (Server)
        Manage the memory duration
        The current memory duration is the memory duration that applies when the mi_alloc() or mi_zalloc() function allocates memory. These functions do not specify a memory duration for their allocation. Instead, they use the current memory duration for the memory they allocate.
        The current memory duration
        Many of the constructor functions assign the current memory duration to the data type structures that they allocate.
        Change the memory duration
        Deallocate user memory
        The database server automatically reclaims the user memory that mi_alloc(), mi_dalloc(), and mi_zalloc() allocate. The memory duration of the user memory determines when the database server marks the memory for deallocation.
        Manage named memory
        Named memory is memory allocated from the database server shared memory, as user memory. You can, however, assign a name to a block of named memory and then access this memory block by name and memory duration. The database server stores the name and its corresponding address internally. By contrast, user memory is always accessed by its address.
        Monitor shared memory
        Manage stack space
        Session threads execute C UDRs and their thread-stack space is allocated from a common region in shared memory. The thread stack stores nonshared data for the UDRs and system routines that the thread executes. This stack contains everything that would normally be on the execution stack, including routine arguments (including the MI_FPARAM structure, local (stack) variables, and function return values.
      - Create special-purpose UDRs
        This section describes how to create special UDRs, such as iterator functions, user-defined aggregates, and optimization functions.
      - Extend data types
        This section describes the ways to extend data types with C user-defined routines (UDRs).
    - Appendix
      This section contains additional reference information.
  - Function Reference
    The IBM® Informix® DataBlade® API Function Reference describes the functions and the subset of functions that the supports.
  - Developers Kit
    The Developers Kit (DBDK) guides contain information about the tools you can use to develop and package modules, which extend the functionality of HCL Informix® databases.
  - J/Foundation Developer's Guide
    The HCL® 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 HCL® 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 HCL® 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 IBM® 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 IBM® 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 module.
Data warehousing
In addition to designing and implementing Informix® dimensional databases, you can use tools to create data warehouse applications and optimize your data warehouse queries.
Designing databases
The first step in creating a relational database is to construct a data model, which is a precise, complete definition of the data you want to store. After you prepare your data model, you must implement it as a database and tables. To implement your data model, you first select a data type for each column and then you create a database and tables and populate the tables with data. You can also implement fragmentation strategies and control access to your data.
JSON compatibility
You can use the popular JSON-oriented query language created by MongoDB to interact with data stored in HCL Informix®.
Security
You can secure your Informix® database server and the data that is stored in your Informix databases. You can encrypt data, secure connections, control user privileges and access, and audit data security.
SQL programming
You can use the HCL Informix® implementation of the SQL language to develop applications for Informix database servers.
Troubleshooting HCL Informix®
Several troubleshooting techniques, tools, and resources are available for resolving problems that you encounter in your HCL Informix® database server environment.

The current memory duration

Many of the constructor functions assign the current memory duration to the data type structures that they allocate.

The following table shows the data type structures that are allocated with the current memory duration.

Table 1. data type structures with the current memory duration
data type structure	constructor function	destructor function
Collection descriptor (MI_COLL_DESC)	mi_collection_open(), mi_collection_open_with_options()	mi_collection_close()
Collection (MI_COLLECTION)	mi_collection_copy(), mi_collection_create(), mi_streamread_collection()	mi_collection_free()
Error descriptor (MI_ERROR_DESC)	mi_error_desc_copy()	mi_error_desc_destroy()
LO handle (MI_LO_HANDLE)	mi_get_lo_handle(), mi_lo_copy(), mi_lo_create(), mi_lo_expand(), mi_lo_from_file(), mi_lo_from_string()	mi_lo_delete_immediate(), mi_lo_release()
LO-specification structure (MI_LO_SPEC)	mi_lo_spec_init()	mi_lo_spec_free()
LO-status structure (MI_LO_STAT)	mi_lo_stat()	mi_lo_stat_free()
MI_LO_LIST	mi_lo_lolist_create()	None
Row descriptor (MI_ROW_DESC)	mi_row_desc_create()	mi_row_desc_free()
Row structure (MI_ROW)	mi_row_create(), mi_streamread_row()	mi_row_free()
Stream descriptor (MI_STREAM)	mi_stream_init(), mi_stream_open_fio(), mi_stream_open_mi_lvarchar(), mi_stream_open_str()	mi_stream_close()
User memory	mi_alloc(), mi_zalloc()	mi_free()
Varying-length structure (mi_lvarchar, mi_sendrecv, mi_impexp, mi_impexpbin)	mi_new_var(), mi_streamread_lvarchar(), mi_string_to_lvarchar(), mi_var_copy()	mi_var_free()

To change the memory duration of a data type structure, call the mi_switch_mem_duration() function with the desired duration before the function call that allocates the object. For more information, see Change the memory duration.

Important: All the functions in data type structures with the current memory duration allocate structures with the current memory duration. If you switch the current memory duration, you affect not only explicit allocations you make with mi_alloc() or mi_zalloc() but the memory allocations that all these constructor functions do as well.