Hello, I have the following table:
CREATE TABLE `list_datas_1` ( `list_id` bigint(20) NOT NULL, `locale_id` bigint(20) NOT NULL, `record_id` bigint(20) NOT NULL, `segment_0` longtext, `segment_1` longtext, `segment_0_sk` longblob, `segment_1_sk` longblob, KEY `record_id` (`record_id`), KEY `list_id` (`list_id`), KEY `datas` (`locale_id`,`segment_0_sk`(677),`segment_1_sk`(338)), CONSTRAINT `list_datas_1_ibfk_1` FOREIGN KEY (`list_id`) REFERENCES `list_definitions` (`list_definition_id`), CONSTRAINT `list_datas_1_ibfk_2` FOREIGN KEY (`locale_id`) REFERENCES `locales` (`locale_id`), CONSTRAINT `list_datas_1_ibfk_3` FOREIGN KEY (`record_id`) REFERENCES `records` (`record_id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8; When I use the following statement: select record_id, segment_0_sk, segment_1_sk from list_datas_1 order by locale_id, substring(segment_0_sk,1,677); explain returns the following datas: +----+-------------+--------------+------+---------------+------ +---------+------+------+----------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+--------------+------+---------------+------ +---------+------+------+----------------+ | 1 | SIMPLE | list_datas_1 | ALL | NULL | NULL | NULL | NULL | 2697 | Using filesort | +----+-------------+--------------+------+---------------+------ +---------+------+------+----------------+ The two columns in the order by clause is a prefix of the 'datas' index. This index is not used at all for the select ? Thanks for you replies. vdg -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
