Function scan

src/jrd/btr.cpp:6733–6960

static bool scan(thread_db* tdbb, UCHAR* pointer, RecordBitmap** bitmap, RecordBitmap* bitmap_and,
				 index_desc* idx, const IndexRetrieval* retrieval, USHORT prefix,
				 temporary_key* key,
				 bool& skipLowerKey, const temporary_key& lowerKey, USHORT forceInclFlag)
{
/**************************************
 *
 *	s c a n
 *
 **************************************
 *
 * Functional description
 *	Do an index scan.
 *  If we run over the bucket, return true.
 *  If we're completely done (passed END_LEVEL),
 *  return false.
 *
 **************************************/
	SET_TDBB(tdbb);

	JRD_reschedule(tdbb);

	// if the search key is flagged to indicate a multi-segment index
	// stuff the key to the stuff boundary
	ULONG count;
	USHORT flag = retrieval->irb_generic;
	flag &= ~forceInclFlag;		// clear exclude bits if needed

	if ((flag & irb_partial) && (flag & irb_equality) &&
		!(flag & irb_starting) && !(flag & irb_descending))
	{
		count = STUFF_COUNT - ((key->key_length + STUFF_COUNT) % (STUFF_COUNT + 1));

		for (ULONG i = 0; i < count; i++)
			key->key_data[key->key_length + i] = 0;

		count += key->key_length;
	}
	else
		count = key->key_length;

	const USHORT to_segment = (idx->idx_count - retrieval->irb_upper_count);
	const UCHAR* const end_key = key->key_data + count;
	count -= key->key_length;

	const bool descending = (flag & irb_descending);
	const bool equality = (flag & irb_equality);
	const bool ignoreNulls = (flag & irb_ignore_null_value_key) && (idx->idx_count == 1);
	bool done = false;
	bool ignore = false;
	const bool skipUpperKey = (flag & irb_exclude_upper);
	const bool partLower = (retrieval->irb_lower_count < idx->idx_count);
	const bool partUpper = (retrieval->irb_upper_count < idx->idx_count);

	// Reset flags this routine does not check in the loop below
	flag &= ~(irb_equality | irb_unique | irb_ignore_null_value_key | irb_root_list_scan);
	flag &= ~(irb_exclude_lower | irb_exclude_upper);