Update index.go

[david-sail]

对索引进行重复检查 如果存在对主键的组合索引覆盖主键索引,不建议对主键进行删除. 按照现在的逻辑会提示PRIMARY与idx_id_district重复.其实这种情况用户绝大多数是想利用“覆盖索引”加速

+-------+------------+---------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+ | dupt1 | 0 | PRIMARY | 1 | ID | A | 0 | NULL | NULL | | BTREE | | | | dupt1 | 1 | CountryCode | 1 | CountryCode | A | 0 | NULL | NULL | | BTREE | | | | dupt1 | 1 | idx_name | 1 | Name | A | 0 | NULL | NULL | | BTREE | | | | dupt1 | 1 | idx_name_coutrycode | 1 | Name | A | 0 | NULL | NULL | | BTREE | | | | dupt1 | 1 | idx_name_coutrycode | 2 | CountryCode | A | 0 | NULL | NULL | | BTREE | | | | dupt1 | 1 | idx_id_district | 1 | ID | A | 0 | NULL | NULL | | BTREE | | | | dupt1 | 1 | idx_id_district | 2 | District | A | 0 | NULL | NULL | | BTREE | | | +-------+------------+---------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+