Seu
ORDER BY na subconsulta da tabela derivada é ignorada no MySQL 5.7. Consulte https://dev.mysql.com/ doc/refman/5.7/en/derived-table-optimization.html
Sua consulta externa tem um JOIN e um GROUP BY, portanto, não se qualifica para propagar o ORDER BY, portanto, ignora o ORDER BY.
Esse comportamento do otimizador é controlado pela chave do otimizador
derived_merge . Você pode desativá-lo. Demonstração:
mysql [localhost] {msandbox} (test) > select @@version;
+-----------+
| @@version |
+-----------+
| 5.7.21 |
+-----------+
mysql [localhost] {msandbox} (test) > SELECT columnPrimaryKey, column1, column2, column3 FROM (SELECT columnPrimaryKey, column1, column2, column3 FROM testTable ORDER BY column2 ) AS tbl GROUP BY column3;
+------------------+----------------+---------+---------+
| columnPrimaryKey | column1 | column2 | column3 |
+------------------+----------------+---------+---------+
| 1 | Some Name 8-4 | 4 | 8 |
| 6 | Some Name 9-1 | 1 | 9 |
| 8 | Some Name 10-2 | 2 | 10 |
+------------------+----------------+---------+---------+
mysql [localhost] {msandbox} (test) > set optimizer_switch = 'derived_merge=off';
Query OK, 0 rows affected (0.00 sec)
mysql [localhost] {msandbox} (test) > SELECT columnPrimaryKey, column1, column2, column3 FROM (SELECT columnPrimaryKey, column1, column2, column3 FROM testTable ORDER BY column2 ) AS tbl GROUP BY column3;
+------------------+----------------+---------+---------+
| columnPrimaryKey | column1 | column2 | column3 |
+------------------+----------------+---------+---------+
| 5 | Some Name 8-1 | 1 | 8 |
| 6 | Some Name 9-1 | 1 | 9 |
| 8 | Some Name 10-2 | 2 | 10 |
+------------------+----------------+---------+---------+
