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.
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.
Purpose-function reference
These topics describe the purpose functions that the access-method developer provides.
Purpose-function syntax
The database server expects a particular prototype for each purpose function. As the access-method developer, you program the actions of a purpose function but must use the parameters and return values that the Virtual-Table Interface (VTI) prototypes specify.
The am_create purpose function
The database server calls am_create to process a CREATE TABLE statement.

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.
  - 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.
    - Access methods
      This section describes access methods, explains why you create user-defined access methods, and shows you how to create user-defined access methods
    - Develop an access method
      These topics describe the steps that you take to implement a user-defined access method with the Virtual-Table Interface (VTI).
    - Design decisions
      These topics present the choices that you make to optimize the performance and flexibility of the access method that you can create with the virtual-table interface (VTI).
    - Purpose-function reference
      These topics describe the purpose functions that the access-method developer provides.
      - Purpose-function flow
        The diagrams in this section show, for each SQL statement, which purpose functions the database server executes. Use the diagrams to determine which purpose functions to implement in the access method.
      - Purpose-function syntax
        The database server expects a particular prototype for each purpose function. As the access-method developer, you program the actions of a purpose function but must use the parameters and return values that the Virtual-Table Interface (VTI) prototypes specify.
        The am_beginscan purpose function
        The database server calls am_beginscan to start a scan on a virtual table. This function initializes the scan.
        The am_check purpose function
        If a user executes the oncheck utility for a virtual table, the database server calls am_check.
        The am_close purpose function
        The database server calls am_close when the processing of a single SQL statement (SELECT, UPDATE, INSERT, DELETE, MERGE) completes.
        The am_create purpose function
        The database server calls am_create to process a CREATE TABLE statement.
        The am_delete purpose function
        The am_drop purpose function
        The database server calls am_drop for a DROP TABLE or DROP DATABASE statement.
        The am_endscan purpose function
        The database server calls am_endscan when am_getnext finds no more rows.
        The am_getbyid purpose function
        The database server calls am_getbyid instead of am_getnext to pass the row identifier instead of a scan descriptor. For example, the database server might obtain the row identifier from an index on the virtual table.
        The am_getnext purpose function
        The am_getnext purpose function identifies rows that meet query criteria.
        The am_insert purpose function
        The database server calls am_insert for an INSERT or UPDATE statement, an ALTER FRAGMENT statement that moves a row to a different fragment, and a MERGE statement, which can perform both INSERT and DELETE or UPDATE operations on the result of an outer join of two tables.
        The am_open purpose function
        The database server calls am_open to initialize input or output before processing an SQL statement.
        The am_rescan purpose function
        The database server typically calls am_rescan to process a join or subquery that requires multiple scans on the same table.
        The am_scancost purpose function
        The query optimizer calls am_scancost during a SELECT statement, before it calls am_open.
        The am_stats purpose function
        The database server calls am_stats to process an UPDATE STATISTICS statement.
        The am_truncate purpose function
        HCL Informix® provides built-in am_truncate purpose functions for its primary access methods that support TRUNCATE operations on columns of permanent and temporary tables. Informix also provides a built-in am_truncate purpose function for its secondary access method for TRUNCATE operations on B-tree indexes.
        The am_update purpose function
        The database server calls am_update to process an UPDATE statement.
    - Descriptor function reference
      These topics provide the syntax and usage for the functions that the HCL Informix® database server supplies to access-method developers.
    - SQL statements for access methods
      These topics describe the syntax and usage of the ALTER ACCESS_METHOD, CREATE PRIMARY ACCESS_METHOD, and DROP ACCESS_METHOD statements, which insert, change, or delete entries in the sysams system catalog table.
    - XA-compliant external data sources
      The HCL Informix® Transaction Manager recognizes XA-compliant external data sources, which can participate in two-phase commit transactions.
  - 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 am_create purpose function

The database server calls am_create to process a CREATE TABLE statement.

Syntax

mi_integer am_create(MI_AM_TABLE_DESC *tableDesc)

tableDesc: Points to the table descriptor.

Usage

Even if the access method does not provide an am_create function, the database server automatically adds the created object to the system catalog tables, such as systables. For example, a user might issue the CREATE TABLE command to register a table in another database of the same database server instance.

The am_create function typically:

Calls accessor functions to extract table specifications from the table descriptor, including a pointer to the row descriptor
Calls functions to extract column attributes from the row descriptor
Verifies that the access method can provide all the requirements that the CREATE TABLE specifies
Calls the appropriate functions to create a smart large object or interact with the operating system for file creation, as described in Manage storage spaces

Important: By default, transaction logging is disabled in sbspaces. To find out how to turn on logging, see Ensure data integrity.

Return values

MI_OK: Indicates success.
MI_ERROR: Indicates failure.

Related topics

In the HCL® Informix® DataBlade® API Programmer's Guide, see the descriptions of:

functions, such as mi_lo_create(), and create-time constants
accessor functions for the row descriptor