Question

我有一张桌子：

CREATE TABLE  `posts` (
  `post_id` mediumint(8) unsigned NOT NULL AUTO_INCREMENT,
  `topic_id` mediumint(8) unsigned NOT NULL DEFAULT '0',
  `forum_id` mediumint(8) unsigned NOT NULL DEFAULT '0',
  `poster_id` mediumint(8) unsigned NOT NULL DEFAULT '0',
  `icon_id` mediumint(8) unsigned NOT NULL DEFAULT '0',
  `poster_ip` varchar(40) COLLATE utf8_bin NOT NULL DEFAULT '',
  `post_time` int(11) unsigned NOT NULL DEFAULT '0',
  `post_approved` tinyint(1) unsigned NOT NULL DEFAULT '1',
  `post_reported` tinyint(1) unsigned NOT NULL DEFAULT '0',
  `enable_bbcode` tinyint(1) unsigned NOT NULL DEFAULT '1',
  `enable_smilies` tinyint(1) unsigned NOT NULL DEFAULT '1',
  `enable_magic_url` tinyint(1) unsigned NOT NULL DEFAULT '1',
  `enable_sig` tinyint(1) unsigned NOT NULL DEFAULT '1',
  `post_username` varchar(255) COLLATE utf8_bin NOT NULL DEFAULT '',
  `post_subject` blob,
  `post_text` mediumtext COLLATE utf8_bin NOT NULL,
  `post_checksum` varchar(32) COLLATE utf8_bin NOT NULL DEFAULT '',
  `post_attachment` tinyint(1) unsigned NOT NULL DEFAULT '0',
  `bbcode_bitfield` varchar(255) COLLATE utf8_bin NOT NULL DEFAULT '',
  `bbcode_uid` varchar(8) COLLATE utf8_bin NOT NULL DEFAULT '',
  `post_postcount` tinyint(1) unsigned NOT NULL DEFAULT '1',
  `post_edit_time` int(11) unsigned NOT NULL DEFAULT '0',
  `post_edit_reason` varchar(255) COLLATE utf8_bin NOT NULL DEFAULT '',
  `post_edit_user` mediumint(8) unsigned NOT NULL DEFAULT '0',
  `post_edit_count` smallint(4) unsigned NOT NULL DEFAULT '0',
  `post_edit_locked` tinyint(1) unsigned NOT NULL DEFAULT '0',
  PRIMARY KEY (`post_id`),
  KEY `forum_id` (`forum_id`),
  KEY `topic_id` (`topic_id`),
  KEY `poster_ip` (`poster_ip`),
  KEY `poster_id` (`poster_id`),
  KEY `post_approved` (`post_approved`),
  KEY `post_username` (`post_username`),
  KEY `tid_post_time` (`topic_id`,`post_time`) USING HASH
) ENGINE=InnoDB AUTO_INCREMENT=22381 DEFAULT CHARSET=utf8 COLLATE=utf8_bin;

正如您所看到的，最后一个索引是“USING HASH” - 但是当我使用show indexes from posts;时，那就是没有显示它

Answer 1

快速Google search之后，我很快发现InnoDB doesn't support HASH indexes，但仍接受表定义中的修饰符。

SHOW CREATE TABLE可能会显示USING HASH，但SHOW INDEXES实际上会显示正在使用的索引类型：

Index_type

使用的索引方法（BTREE，FULLTEXT，HASH，RTREE）。

InnoDB，如何检测索引类型？

1 个答案: