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 extensionsYou 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 GuideThe Informix® DataBlade® API Programmer's Guide describes information about the DataBlade® API, the C-language application programming interface (API) provided with HCL Informix®.
Create user-defined routines
Write a user-defined routineThis section outlines some implementation issues for C user-defined routines (UDRs). This section also describes the specific features and tasks of a C UDR.
Virtual processorsTo service multiple client-application SQL requests, the database server uses virtual processors (VPs). The database server breaks the SQL request into distinct tasks, based on the resource that the task requires. Different VP types, called virtual-processor classes (VP classes), service the different kinds of tasks.
Create a well-behaved routine
Choose the user-defined VP class

Choose the user-defined VP class

When you run your C UDR in a user-defined VP, you can relax some, but not all, of the CPU VP safe-code requirements (Safe-code requirements for a well-behaved UDR ). You must choose a user-defined VP that is appropriate for the ill-behaved traits of your UDR. The following types of user-defined VPs allow a C UDR to contain the ill-behaved traits.


Type of user-defined VP	Purpose
Yielding user-defined VP	Prevents a UDR from blocking the CPU VP because it blocks a user-defined VP thread
Nonyielding user-defined VP	Preserves global state of the VP across one UDR invocation
Single-instance user-defined VP	Preserves global state of the VP across all UDR invocations and instances

Important: The user-defined VP class frees the CPU VPs from effects of some ill-behaved traits of a UDR. However, this VP class provides little protection from process failures. Even when the UDR runs in a user-defined VP class, programming errors that cause process failures can severely affect the database server.

Rate this topic

5 stars 4 stars 3 stars 2 stars 1 star

Comment on this topic.

By clicking this box, you acknowledge that you are NOT a U.S. Federal Government employee or agency, nor are you submitting information with respect to or on behalf of one. HCL provides software and services to U.S. Federal Government customers through its partners immixGroup, Inc. Contact this team at https://hcltechsw.com/resources/us-government-contact. Do not include any personal data in this Comment box.