SQL4007 - Query implementation for join position &1 table &2

SQL4007
Message Text: Query implementation for join position &1 table &2
Cause Text: The join position identifies the order in which the tables are joined. A join position of 1 indicates this table is the first, or left most, table in the join order. The table number refers to the relative position of this table in the query.
Recovery Text: Join order can be influenced by adding an ORDER BY clause to the query. Refer to Join optimization for more information about join optimization and tips to influence join order.