protected final Tuple peekNext()
	throws SQLException
	{
		if(m_nextRow != null)
			return m_nextRow;

		TupleTable table = this.getTupleTable();
		if(table == null)
			return null;

		if(m_tableRow >= table.getCount() - 1)
		{
			// Current table is exhaused, get the next
			// one.
			//
			m_table = null;
			table = this.getTupleTable();
			if(table == null)
				return null;
		}
		m_nextRow = table.getSlot(++m_tableRow);
		return m_nextRow;
	}