Describe API

The _describe_extfn function is a member of a_v4_extfn_proc. A UDF gets and sets logical properties using the describe_column, describe_parameter, and describe_udf properties in the a_v4_extfn_proc_context object.

_describe_extfn Declaration

void (UDF_CALLBACK *_describe_extfn)(a_v4_extfn_proc_context *cntxt );
)

Usage

The _describe_extfn function describes the procedure evaluation to the server.

Each of the describe_column, describe_parameter, and describe_udf properties has an associated get and set method, a set of attribute types, and an associated data type for each attribute. The get methods retrieve information from the server; the set methods describe the logical properties of the UDF (such as the number of output columns or the number of distinct values for a output column) to the server.

*describe_column_get
The describe_column_get v4 API method is used by the table UDF to retrieve properties about an individual column of a table parameter.
*describe_column_set
The describe_column_set v4 API method sets UDF column-level properties on the server.
*describe_parameter_get
The describe_parameter_get v4 API method gets UDF parameter properties from the server.
*describe_parameter_set
The describe_parameter_set v4 API method sets properties about a single parameter to the UDF.
*describe_udf_get
The describe_udf_get v4 API method gets UDF properties from the server.
*describe_udf_set
The describe_udf_set v4 API method sets UDF properties on the server.

Parent topic: API Reference for a_v4_extfn