The mi_key_opclass_supt() accessor function

Syntax

mi_string* mi_key_opclass_supt(MI_AM_KEY_DESC *keyDesc,
   mi_integer keyNum,
   mi_integer supportNum)

keyDesc

Points to the key descriptor.

keyNum

Specifies the column number of a key in a composite-key index or 0 for a single-key index.

For the first (or only) key, pass 0 as keyNum. Increment keyNum by 1 for each subsequent key in a composite index.

supportNum

Identifies this support function.

Usage

Each call to mi_key_opclass_supt() returns the name of one support function for one key column.

The supportNum value for the first support function is 0. To determine the number of support functions that mi_key_opclass_supt() can return for a particular key column, call mi_key_opclass_nsupt(). To determine the maximum keyNum value, first call mi_key_nkeys(). For an example of how to use these functions together, see Extracting support functions for a multiple-column index key.

The mi_key_opclass_supt() returns support function names in the order that the CREATE OPCLASS statement names them.

The access method can optionally use the support function name to get the function descriptor that the DataBlade® API FastPath facility uses to execute the support function.

Return values

The string contains the support-function name.

A NULL-valued pointer indicates an invalid value for either the keyNum or strategyNum argument.