Function BTR_key_length

src/jrd/btr.cpp:1600–1735

USHORT BTR_key_length(thread_db* tdbb, jrd_rel* relation, index_desc* idx)
{
/**************************************
 *
 *	B T R _ k e y _ l e n g t h
 *
 **************************************
 *
 * Functional description
 *	Compute the maximum key length for an index.
 *
 **************************************/
	SET_TDBB(tdbb);

	// hvlad: in ODS11 key of descending index can be prefixed with
	//		  one byte value. See comments in compress
	const SLONG prefix = (idx->idx_flags & idx_descending) ? 1 : 0;

	const Format* format = MET_current(tdbb, relation);
	index_desc::idx_repeat* tail = idx->idx_rpt;

	SLONG length;

	// If there is only a single key, the computation is straightforward.
	if (idx->idx_count == 1)
	{
		switch (tail->idx_itype)
		{
		case idx_numeric:
			length = sizeof(double);
			break;

		case idx_sql_time:
		case idx_sql_time_tz:
			length = sizeof(ULONG);
			break;

		case idx_sql_date:
			length = sizeof(SLONG);
			break;

		case idx_timestamp:
		case idx_timestamp_tz:
			length = sizeof(SINT64);
			break;

		case idx_numeric2:
			length = INT64_KEY_LENGTH;
			break;

		case idx_boolean:
			length = sizeof(UCHAR);
			break;

		case idx_decimal:
			length = Decimal128::getIndexKeyLength();
			break;