EXTFNAPIV4_DESCRIBE_PARM_TABLE_PARTITIONBY (Set)

Data Type

a_v4_extfn_column_list

Description

UDF developers use EXTFNAPIV4_DESCRIBE_PARM_TABLE_PARTITIONBY to programmatically declare that the UDF requires partitioning before invocation can proceed.

Usage

The UDF can inquire to the partition to enforce it, or to dynamically adapt the partitioning. The UDF must allocate the a_v4_extfn_column_list, taking into consideration the total number of columns in the input table, and sending that data to the server.

Returns

sizeof(a_v4_extfn_column_list) + sizeof(a_sql_uint32) * number_of_partition_columns

On failure, returns one of the generic describe_parameter errors or:

• EXTFNAPIV4_DESCRIBE_BUFFER_SIZE_MISMATCH – Set error returned if the buffer length is less than the expected size.

Query Processing States

Example

void UDF_CALLBACK my_tpf_proc_describe( a_v4_extfn_proc_context *ctx )
{
	if( ctx->current_state == EXTFNAPIV4_STATE_ANNOTATION ) {
		a_sql_int32	rc = 0;
		a_v4_extfn_column_list pbcol = 
		{ 1,		// 1 column in the partition by list
		2 };	// column index 2 requires partitioning

		// Describe partitioning for argument 1 (the table)
		rc = ctx->describe_parameter_set( 
		ctx, 1, 
		EXTFNAPIV4_DESCRIBE_PARM_TABLE_PARTITIONBY, 
		&pbcol, 
		sizeof(pbcol) );

		if( rc == 0 ) {
		ctx->set_error( ctx, 17000, 
			“Runtime error, unable set partitioning requirements for column.” );
		}
	}
}