mariadb mioux@:Prisme> alter table pdc_client add index idx_toto(cgp, partenaire);
Query OK, 0 rows affected
Time: 5.778s
mariadb mioux@:Prisme> explain SELECT count(*)
                                 -> FROM `pdc_client`
                                 -> WHERE partenaire in(19765,19764)
                                 -> AND `cgp` = 11241
                                 -> LIMIT 50
                                 -> ;
+------+---------------+------------+--------+-------------------------+----------+-----------+--------+--------+--------------------------+
| id   | select_type   | table      | type   | possible_keys           | key      | key_len   | ref    | rows   | Extra                    |
|------+---------------+------------+--------+-------------------------+----------+-----------+--------+--------+--------------------------|
| 1    | SIMPLE        | pdc_client | range  | cgp,partenaire,idx_toto | idx_toto | 8         | <null> | 1085   | Using where; Using index |
+------+---------------+------------+--------+-------------------------+----------+-----------+--------+--------+--------------------------+
1 row in set
Time: 0.006s
mariadb mioux@:Prisme> SELECT count(*)
                                 -> FROM `pdc_client`
                                 -> WHERE partenaire in(19765,19764)
                                 -> AND `cgp` = 11241
                                 -> LIMIT 50
                                 -> ;
+------------+
| count(*)   |
|------------|
| 1085       |
+------------+
1 row in set
Time: 0.017s