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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
Manage memoryA 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 memoryWhen a C UDR executes in a virtual processor (VP), it allocates memory from the shared memory of the database server.
Choose the memory duration
Public memory durationsThe DataBlade® API memory-management functions support several public memory durations. A UDR can use a public memory duration for most dynamic allocations of memory.
The PER_STATEMENT memory durationA PER_STATEMENT memory pool can be associated with each SQL statement, until execution of the statement is complete and for a prepared statement, until the statement terminates. The statement includes any SQL commands that the SQL statement initiates.

The PER_STATEMENT memory duration

A PER_STATEMENT memory pool can be associated with each SQL statement, until execution of the statement is complete and for a prepared statement, until the statement terminates. The statement includes any SQL commands that the SQL statement initiates.

Important: The PER_STATEMENT memory duration is supported for compatibility with existing UDRs. In new code, you must use either the PER_STMT_EXEC or PER_STMT_PREP memory duration. These more precise memory durations replace PER_STATEMENT, which is deprecated.

When a C UDR allocates memory with the PER_STATEMENT memory duration, this memory is available to all routine instances that execute in the same SQL statement.

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