Mysql分区报错，另外小说订阅表如何优化？

CREATE TABLE `yy_subscribe2` (

  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,

  `user_id` int(10) unsigned NOT NULL comment '用户id',

  `book_id` int(10) unsigned NOT NULL comment '小说id',

  `chapter_id` int(10) unsigned NOT NULL comment '章节id',

  PRIMARY KEY (`id`),

  key book_id(book_id),

  key user_id(user_id),

  key chapter_id(chapter_id)

) ENGINE=InnoDB DEFAULT CHARSET=utf8  

PARTITION BY RANGE (user_id) 

( 

    PARTITION s0 values LESS THAN (100000),

    PARTITION s1 values LESS THAN (200000),

    PARTITION s2 values LESS THAN (300000),

    PARTITION s3 values LESS THAN (400000),

    PARTITION s4 values LESS THAN (500000),

    PARTITION s5 values LESS THAN (600000),

    PARTITION s6 values LESS THAN (700000),

    PARTITION s7 values LESS THAN (800000),

    PARTITION s8 values LESS THAN (900000),

    PARTITION s9 values LESS THAN (1000000),

    PARTITION s10 values LESS THAN (1100000),

    PARTITION s11 values LESS THAN (1200000),

    PARTITION s12 values LESS THAN (1300000),

    PARTITION s13 values LESS THAN (1400000), 

    PARTITION s999 values LESS THAN MAXVALUE

);