+----+--------------+-----------------+--------+-----------------------------------------------------------------+----------------------+---------+-------------------------------+-------+----------------------------------------------------+
| id | select_type  | table           | type   | possible_keys                                                   | key                  | key_len | ref                           | rows  | Extra                                              |
+----+--------------+-----------------+--------+-----------------------------------------------------------------+----------------------+---------+-------------------------------+-------+----------------------------------------------------+
|  1 | PRIMARY      | <derived2>      | ALL    | NULL                                                            | NULL                 | NULL    | NULL                          | 15550 | Using temporary; Using filesort                    |
|  1 | PRIMARY      | Bridge          | ref    | bethIdKeyIdx,stringNameKeyIdx,stringValueKeyIdx,attrCombinedIdx | bethIdKeyIdx         | 8       | Beth.id                       |     1 | NULL                                               |
|  1 | PRIMARY      | AttributeName   | eq_ref | PRIMARY,stringId_UNIQUE                                         | PRIMARY              | 8       | polaris.Bridge.stringNameKey  |     1 | NULL                                               |
|  1 | PRIMARY      | AttributeValue  | eq_ref | PRIMARY,stringId_UNIQUE                                         | PRIMARY              | 8       | polaris.Bridge.stringValueKey |     1 | NULL                                               |
|  2 | DERIVED      | <derived3>      | ALL    | NULL                                                            | NULL                 | NULL    | NULL                          |     2 | NULL                                               |
|  2 | DERIVED      | MatchingParent  | eq_ref | PRIMARY,id_UNIQUE                                               | PRIMARY              | 8       | FilteredBeth.id               |     1 | NULL                                               |
|  3 | DERIVED      | AttributeName2  | const  | PRIMARY,value_UNIQUE,stringId_UNIQUE                            | value_UNIQUE         | 257     | const                         |     1 | Using index                                        |
|  3 | DERIVED      | AttributeValue2 | const  | PRIMARY,value_UNIQUE,stringId_UNIQUE                            | value_UNIQUE         | 257     | const                         |     1 | Using index                                        |
|  3 | DERIVED      | Bridge2         | ref    | bethIdKeyIdx,stringNameKeyIdx,stringValueKeyIdx,attrCombinedIdx | stringValueKeyIdx    | 8       | const                         |     1 | Using where                                        |
|  3 | DERIVED      | Beth            | eq_ref | PRIMARY,id_UNIQUE                                               | PRIMARY              | 8       | polaris.Bridge2.bethIdKey     |     1 | NULL                                               |
|  4 | UNION        | MatchingChild   | range  | IDX_6B7D0EA710EE4CEE                                            | IDX_6B7D0EA710EE4CEE | 9       | NULL                          |  7774 | Using index condition                              |
|  4 | UNION        | <derived5>      | ALL    | NULL                                                            | NULL                 | NULL    | NULL                          |     2 | Using where; Using join buffer (Block Nested Loop) |
|  5 | DERIVED      | AttributeName1  | const  | PRIMARY,value_UNIQUE,stringId_UNIQUE                            | value_UNIQUE         | 257     | const                         |     1 | Using index                                        |
|  5 | DERIVED      | AttributeValue1 | const  | PRIMARY,value_UNIQUE,stringId_UNIQUE                            | value_UNIQUE         | 257     | const                         |     1 | Using index                                        |
|  5 | DERIVED      | Bridge1         | ref    | bethIdKeyIdx,stringNameKeyIdx,stringValueKeyIdx,attrCombinedIdx | stringValueKeyIdx    | 8       | const                         |     1 | Using where                                        |
|  5 | DERIVED      | Beth            | eq_ref | PRIMARY,id_UNIQUE                                               | PRIMARY              | 8       | polaris.Bridge1.bethIdKey     |     1 | NULL                                               |
| NULL | UNION RESULT | <union2,4>      | ALL    | NULL                                                            | NULL                 | NULL    | NULL                          |  NULL | Using temporary                                    |
+----+--------------+-----------------+--------+-----------------------------------------------------------------+----------------------+---------+-------------------------------+-------+----------------------------------------------------+
17 rows in set (0.00 sec)