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Client APIs and tools
You can use the HCL Informix® implementation of client APIs to develop applications for Informix database servers.
Informix® ODBC Driver Guide
The Informix® ODBC Driver Programmer's Manual serves as a user guide and reference for Informix ODBC Driver, which is the Informix implementation of the Microsoft™ Open Database Connectivity (ODBC) interface, Version 3.0.
Improve application performance
These topics suggest ways to improve performance of Informix® ODBC Driver applications.
Optimizing query execution
There are several items you must consider when using prepared SQL queries.

Client APIs and tools
You can use the HCL Informix® implementation of client APIs to develop applications for Informix database servers.
- Change Data Capture API Programmer's Guide
  The Informix® Change Data Capture API Programmer's Guide describes how to program applications to process changed data from HCL Informix databases using the Informix Change Data Capture API.
- Embedded SQLJ for HCL Informix®
  The Informix® Embedded SQLJ User's Guide contains information about using Informix Embedded SQLJ.
- ESQL/C Guide
  The Informix® ESQL/C Programmer's Manual explains how to use Informix ESQL/C, the Informix implementation of Embedded Structured Query Language (SQL) for C (ESQL/C), to create client applications with database-management capabilities.
- GLS User's Guide
  The Informix® GLS User's Guide describes the Global Language Support (GLS) feature available in Informix products.
- API
  The Informix® GLS API Programmer's Guide describes the global language support (GLS) application programming interface (API) available in Informix ESQL/C and HCL Informix DataBlade® modules.
- Informix® Object Interface for C++ Guide
  The Informix® Object Interface for C++ Programmer's Guide describes how to develop HCL Informix client applications by using the object-oriented C++ programming language.
- Informix® ODBC Driver Guide
  The Informix® ODBC Driver Programmer's Manual serves as a user guide and reference for Informix ODBC Driver, which is the Informix implementation of the Microsoft™ Open Database Connectivity (ODBC) interface, Version 3.0.
  - Overview of HCL Informix® ODBC Driver
    These topics introduce the Informix® ODBC Driver and describe its advantages and architecture. The topics also describe conformance, isolation and lock levels, libraries, and environment variables.
  - Configure data sources
    These topics explain how to configure a data source (DSN) on UNIX™ and Windows™ for Informix® ODBC Driver.
  - Data types
    These topics contain information about the data types that are supported by Informix® ODBC Driver.
  - Smart large objects
    These topics describe how to store, create, and access a smart large object; how to transfer smart-large-object data; how to retrieve the status of a smart large object; and how to read or write a smart large object to or from a file.
  - Rows and collections
    Rows and collections are composite values that consist of one or more elements.
  - Client functions
    These topics describe the Informix® ODBC Driver client functions. Use these functions to access and manipulate smart large objects and rows and collections.
  - Application tracking in ODBC
    Set the CLIENT_LABEL environment variable in CSDK 4.50.xC4 onwards to assign a character string to ODBC client session and identify that character string on the database server. You can use this variable to distinguish one database session from the other.
  - Improve application performance
    These topics suggest ways to improve performance of Informix® ODBC Driver applications.
    - Error checking during data transfer
      The IFX_LOB_XFERSIZE environment variable is used to specify the number of kilobytes in a CLOB or BLOB to transfer from a client application to the database server before checking whether an error has occurred.
    - Enable delimited identifiers in ODBC
      By default delimited identifiers are disabled when connecting through ODBC.
    - Connection level optimizations
      Establishing a connection to a database is an expensive process. Optimally, an application performs as many tasks as possible while a connection is open.
    - Optimizing query execution
      There are several items you must consider when using prepared SQL queries.
    - Insert multiple rows
      Use an insert cursor to efficiently insert rows into a table in bulk.
    - Automatically freeing a cursor
      When an application uses a cursor, it usually sends a FREE statement to the database server to deallocate memory assigned to a cursor after it no longer needs that cursor.
    - Delay execution of the SQL PREPARE statement
      You can defer execution of the SQLPrepare statement by enabling the deferred-PREPARE feature.
    - Set the fetch array size for simple-large-object data
      To reduce the network overhead for fetches involving multiple rows of simple-large-object data, you can set the array size.
    - The SPL output parameter feature
      Informix® ODBC Driver supports the ODBC defined method of getting the return value from a database procedure.
    - OUT and INOUT parameters
      As of , Informix® Client Software Development Kit supports the use of OUT and INOUT parameters during execution of SPL.
    - Asynchronous execution
      Design your application to take advantage of data sources that support asynchronous execution. Asynchronous calls do not perform faster, but well-designed applications appear to run more efficiently.
    - Update data with positioned updates and deletes
      Although positioned updates do not apply to all types of applications, try to use positioned updates and deletes whenever possible.
    - BIGINT and BIGSERIAL data types
      BIGINT and BIGSERIAL data types have the same range of values as INT8 and SERIAL8 data types.
    - Message transfer optimization
      If you activate the message transfer optimization feature (OPTMSG), the driver minimizes message transfers with the database server for most HCL Informix® ODBC functions.
  - Error messages
    These topics describe the Informix® ODBC Driver error messages.
  - Unicode
    These topics provide a brief overview of the Unicode standard and shows how it is used within ODBC applications.
  - ODBC Smart trigger
- .NET provider options
  The Data Server Provider for .NET DB2® provider option is the preferred Informix® provider for developing new applications.
- Informix® JDBC Driver Guide
  The Informix® JDBC Driver Programmer's Guide describes how to install, load, and use Informix JDBC Driver to connect to the Informix database from within a Java™ application or applet.
- Informix International Language Supplement (ILS) User Guide
  These topics include information about the translated user interface files for Informix® UNIX™ products, locales, and code set conversion tables
- Informix® OLE DB Provider Guide
  The Informix® OLE DB Provider Programmer's Guide describes the software requirements for using Informix OLE DB Provider, show how to install and configure the provider for your use, and explain how to use Informix OLE DB Provider to enable client applications, such as ActiveX Data Object (ADO) applications and web pages, to access data on the Informix server.

Optimizing query execution

There are several items you must consider when using prepared SQL queries.

Consider the following when using prepared SQL queries:

SQLExecDirect is optimized for a single execution of an SQL statement. Thus, it is used for SQL queries that are not executed repeatedly.
In cases where SQL queries are executed multiple times, using SQLPrepare and SQLExecute improves performance. Typically, you can do this with input and output parameters.
SPL routines can be called from an ODBC application to perform certain SQL tasks and to expand what you can accomplish with SQL alone. Because SPL is native to the database and SPL routines are parsed and optimized at creation, rather than at runtime, SPL routines can improve performance for some tasks. SPL routines can also reduce traffic between a client application and the database server and reduce program complexity.
When a stored procedure with a return value is executed using the HCL Informix® ODBC Driver, errors returned by the procedure are not returned to the application until a fetch is called on the result set. Error information from stored procedures with no returned values is available immediately following the execution of the procedure.