Engine independent statistics only allows utf8 values, making query plans fail

Error formatting macro: code: java.lang.StackOverflowError

CREATE DATABASE zhwiki;
use zhwiki;
CREATE TABLE `recentchanges` (
`rc_id` int(8) NOT NULL AUTO_INCREMENT,
`rc_timestamp` varbinary(14) NOT NULL DEFAULT '',
`rc_cur_time` varbinary(14) NOT NULL DEFAULT '',
`rc_user` int(10) unsigned NOT NULL DEFAULT '0',
`rc_user_text` varbinary(255) NOT NULL DEFAULT '',
`rc_namespace` int(11) NOT NULL DEFAULT '0',
`rc_title` varbinary(255) NOT NULL DEFAULT '',
`rc_comment` varbinary(255) NOT NULL DEFAULT '',
`rc_minor` tinyint(3) unsigned NOT NULL DEFAULT '0',
`rc_bot` tinyint(3) unsigned NOT NULL DEFAULT '0',
`rc_new` tinyint(3) unsigned NOT NULL DEFAULT '0',
`rc_cur_id` int(10) unsigned NOT NULL DEFAULT '0',
`rc_this_oldid` int(10) unsigned NOT NULL DEFAULT '0',
`rc_last_oldid` int(10) unsigned NOT NULL DEFAULT '0',
`rc_type` tinyint(3) unsigned NOT NULL DEFAULT '0',
`rc_source` varbinary(16) NOT NULL DEFAULT '',
`rc_moved_to_ns` tinyint(3) unsigned NOT NULL DEFAULT '0',
`rc_moved_to_title` varbinary(255) NOT NULL DEFAULT '',
`rc_patrolled` tinyint(3) unsigned NOT NULL DEFAULT '0',
`rc_ip` varbinary(40) NOT NULL DEFAULT '',
`rc_old_len` int(10) DEFAULT NULL,
`rc_new_len` int(10) DEFAULT NULL,
`rc_deleted` tinyint(1) unsigned NOT NULL DEFAULT '0',
`rc_logid` int(10) unsigned NOT NULL DEFAULT '0',
`rc_log_type` varbinary(255) DEFAULT NULL,
`rc_log_action` varbinary(255) DEFAULT NULL,
`rc_params` blob NOT NULL,
PRIMARY KEY (`rc_id`),
KEY `rc_timestamp` (`rc_timestamp`),
KEY `rc_namespace_title` (`rc_namespace`,`rc_title`),
KEY `rc_cur_id` (`rc_cur_id`),
KEY `new_name_timestamp` (`rc_new`,`rc_namespace`,`rc_timestamp`),
KEY `rc_ip` (`rc_ip`),
KEY `rc_ns_usertext` (`rc_namespace`,`rc_user_text`),
KEY `rc_user_text` (`rc_user_text`,`rc_timestamp`)
) ENGINE=InnoDB AUTO_INCREMENT=52457042 DEFAULT CHARSET=binary

– Note the charset binary, this allows any character encoding

INSERT INTO `recentchanges` VALUES (51267205,'20151023001221','',0,'Reinheitsgebot',0,'��鯰科','添加语言链接：[[:specieswiki:Pangasiidae]]',1,1,0,566064,36471314,36471314,5,'wb',0,'',1,'',1254,1254,0,0,NULL,'','a:3:{s:20:\"wikibase-repo-change\";a:14:

{s:2:\"id\";i:259555851;s:4:\"type\";s:20:\"wikibase-item~update\";s:4:\"time\";s:14:\"20151023001221\";s:9:\"object_id\";s:7:\"q901080\";s:7:\"user_id\";s:6:\"940976\";s:11:\"revision_id\";s:9:\"261218043\";s:11:\"entity_type\";s:4:\"item\";s:9:\"user_text\";s:14:\"Reinheitsgebot\";s:7:\"page_id\";i:851866;s:9:\"parent_id\";i:255341522;s:7:\"comment\";s:49:\"/* wbsetsitelink-add:1|specieswiki */ Pangasiidae\";s:6:\"rev_id\";i:261218043;s:3:\"bot\";i:1;s:7:\"site_id\";s:12:\"wikidatawiki\";}

s:7:\"comment\";s:49:\"添加语言链接：[[:specieswiki:Pangasiidae]]\";s:12:\"comment-html\";s:123:\"添加语言链接：<a class=\"external\" href=\"//www.wikidata.org/wiki/Specieswiki:Pangasiidae\">specieswiki:Pangasiidae</a>\";}');

SET GLOBAL use_stat_tables=PREFERABLY;

– reload connection for change to take effect to your current session

MariaDB [zhwiki]> ANALYZE TABLE recentchanges;
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We can check that effectively, the tables have the wrong encoding:

CREATE TABLE `column_stats` (
`db_name` varchar(64) COLLATE utf8_bin NOT NULL,
`table_name` varchar(64) COLLATE utf8_bin NOT NULL,
`column_name` varchar(64) COLLATE utf8_bin NOT NULL,
`min_value` varchar(255) COLLATE utf8_bin DEFAULT NULL,
`max_value` varchar(255) COLLATE utf8_bin DEFAULT NULL,
`nulls_ratio` decimal(12,4) DEFAULT NULL,
`avg_length` decimal(12,4) DEFAULT NULL,
`avg_frequency` decimal(12,4) DEFAULT NULL,
`hist_size` tinyint(3) unsigned DEFAULT NULL,
`hist_type` enum('SINGLE_PREC_HB','DOUBLE_PREC_HB') COLLATE utf8_bin DEFAULT NULL,
`histogram` varbinary(255) DEFAULT NULL,
PRIMARY KEY (`db_name`,`table_name`,`column_name`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_bin COMMENT='Statistics on Columns'

With 1.4 millons rows, a simple query like:

FLUSH STATUS;
SELECT /* ApiQueryRecentChanges::run SANITIZED */ rc_id,rc_timestamp,rc_namespace,rc_title,rc_cur_id,rc_type,rc_deleted,rc_this_oldid,rc_last_oldid,rc_user,rc_user_text,ts_tags,page_is_redirect FROM `recentchanges` LEFT JOIN `tag_summary` ON ((rc_id=ts_rc_id)) LEFT JOIN `page` ON ((rc_namespace=page_namespace) AND (rc_title=page_title)) WHERE rc_namespace = '0' AND rc_type = '1' AND (rc_patrolled = 0) AND (page_is_redirect = 0 OR page_is_redirect IS NULL) AND rc_new=1 ORDER BY rc_timestamp DESC,rc_id DESC LIMIT 51;
SHOW STATUS like 'Hand%';

goes from reading 3000 rows to read the full table (full index scan) using the timestamp index, 1.4 millon rows.