小编Jim*_*mbo的帖子

我有一个拒绝使用索引的表,它总是使用filesort.

该表是:

CREATE TABLE `article` (
  `ID` int(11) NOT NULL AUTO_INCREMENT,
  `Category_ID` int(11) DEFAULT NULL,
  `Subcategory` int(11) DEFAULT NULL,
  `CTimestamp` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
  `Publish` tinyint(4) DEFAULT NULL,
  `Administrator_ID` int(11) DEFAULT NULL,
  `Position` tinyint(4) DEFAULT '0',
  PRIMARY KEY (`ID`),
  KEY `Subcategory` (`Subcategory`,`Position`,`CTimestamp`,`Publish`),
  KEY `Category_ID` (`Category_ID`,`CTimestamp`,`Publish`),
  KEY `Position` (`Position`,`Category_ID`,`Publish`),
  KEY `CTimestamp` (`CTimestamp`),
  CONSTRAINT `article_ibfk_1` FOREIGN KEY (`Category_ID`) REFERENCES `category` (`ID`)
) ENGINE=InnoDB AUTO_INCREMENT=94290 DEFAULT CHARSET=utf8

查询是:

SELECT * FROM article ORDER BY `CTimestamp`;

解释是:

+----+-------------+---------+------+---------------+------+---------+------+-------+----------------+
| id | select_type | …