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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.
User-Defined Routines and Data Types Developer's GuideThe 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®.
A user-defined routine
Tasks that you can perform with user-defined routines
Support user-defined data types
Optimization functions

Optimization functions

Optimization functions help the query optimizer determine the most efficient query plan for a particular SQL statement. These optimization functions are as follows.

Negator function: Specifies the function to use for a NOT condition that involves a Boolean UDR
Cost function: Specifies the cost factor for execution of a particular UDR
Selectivity function: Specifies the percentage of rows for which a Boolean UDR is expected to return true
Parallel UDR: A UDR that can be run in parallel and therefore can be run in parallel queries
Statistics function: Creates distribution statistics for a UDT

The database server provides optimization functions for the built-in data types. You can write an optimization function on any UDT that is registered in the database. You cannot extend existing optimization for built-in types through optimization functions.

For more information about optimization functions, see Improve UDR performance.

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