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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
Extend data typesThis section describes the ways to extend data types with C user-defined routines (UDRs).
Provide statistics data for a columnThe database server can provide statistics data for the columns of a table. This statistics data describes the distribution of the values within a column. The query optimizer uses this statistics data to determine the best path for an SQL statement. With this information, the optimizer can estimate the effect of a WHERE clause by examining, for each column included in the WHERE clause, the proportionate occurrence of data values contained in the column.
User-defined statistics
Display statistics dataThe dbschema utility with its -hd option displays statistics data for tables in your database. It can automatically display statistics for all columns with built-in data types (except TEXT and BYTE). It cannot automatically collect statistics for columns with user-defined data types because it does not know the structure of these data types.
Define a statistics-display function

Define a statistics-display function

When you declare your statistics-display function, it must have the following signature:

mi_lvarchar *statprint(udt_arg, stat_arg)
   udt_type *udt_arg;
   mi_statret *stat_arg;

udt_arg: A pointer to a placeholder argument. The database server uses this argument to resolve the function and to pass in column values.
stat_arg: A pointer to the mi_statret structure that contains the statistics information for the user-defined data type.

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