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Extending HCL OneDB™Beyond standard relational database objects, HCL OneDB™ can be extended to handle specialized data types, access methods, routines, and other objects. HCL OneDB™ includes many built-in extensions that are fully integrated in the database server. HCL OneDB™ 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 HCL OneDB™.
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 HCL OneDB™ databases.
DataBlade® API Function ReferenceThe HCL OneDB™ DataBlade® API Function Reference describes the DataBlade® API functions and the subset of functions that the DataBlade® API supports.
Function descriptionsThis section gives comprehensive reference information about the functions that are valid within DataBlade® API modules. It lists the function descriptions in alphabetical order, with syntax, usage information, and return values for the functions.
The mi_funcarg_get_distrib() functionThe mi_funcarg_get_distrib() function returns the data-distribution information for the column associated with the companion-UDR argument of a cost or selectivity function.

The mi_funcarg_get_distrib() function

The mi_funcarg_get_distrib() function returns the data-distribution information for the column associated with the companion-UDR argument of a cost or selectivity function.

Syntax

mi_bitvarying *mi_funcarg_get_distrib(funcarg_ptr)
   MI_FUNCARG *funcarg_ptr;

funcarg_ptr

A pointer to the MI_FUNCARG structure that describes the companion-UDR argument.


Valid in client LIBMI application?	Valid in user-defined routine?
No	Yes

Usage

The mi_funcarg_get_distrib() function returns data-distribution information from the MI_FUNCARG structure that funcarg_ptr references. The MI_FUNCARG structure describes an argument of a companion UDR to its cost or selectivity function. Use the mi_funcarg_get_distrib() function only for companion-UDR arguments that are column values; that is, only arguments for which the mi_funcarg_get_argtype() function returns the MI_FUNCARG_COLUMN value.

The data-distribution information is either an ASCII histogram that divides the column values into a prescribed number of bins or it is user-defined statistics. It is the value from the encdat column of the sysdistrib system catalog table. The mi_funcarg_get_distrib() function returns the data-distribution information as an mi_bitvarying varying-length structure. The varying-length data is an mi_statret structure, which contains the actual data distribution.

Use the mi_funcarg_get_distrib() function in a cost or selectivity function to obtain the distribution information for the column with which an argument passed into the expensive UDR is associated.

For more information about cost and selectivity, see the HCL OneDB™ DataBlade® API Programmer's Guide.

Return values

An mi_bitvarying pointer

A pointer to a varying-length structure that contains the data-distribution information for the column associated with the companion-UDR argument.

NULL

This value indicates one of the following conditions:

No data-distribution information exists for the column.
The companion-UDR argument is not of type MI_FUNCARG_COLUMN.
The function was not successful.