Mark Samman added a comment - 2018-02-11 17:59 I just had this happen again with server version 10.2.12. The most recent DDL was within the past 12 hours, and it was: ALTER TABLE `user_notifications` CHANGE COLUMN `match_id` `data` JSON DEFAULT NULL ; It's possible that it's triggered by a bug in my application that uses the Go MySQL driver since there was a memory inconsistency bug last time this happened, and today there was another bug with the buffers used when reading rows from SELECT queries. MariaDB [esportal]> show create table matchmaking_match; + -------------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+ | Table | Create Table | + -------------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+ | matchmaking_match | CREATE TABLE `matchmaking_match` ( `id` bigint (20) unsigned NOT NULL AUTO_INCREMENT, `region_id` tinyint(1) unsigned NOT NULL , `inserted` int (10) unsigned NOT NULL , PRIMARY KEY (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=153661 DEFAULT CHARSET=utf8 | + -------------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+ 1 row in set (0.00 sec)   MariaDB [esportal]> show create table matchmaking_match_users; + -------------------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+ | Table | Create Table | + -------------------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+ | matchmaking_match_users | CREATE TABLE `matchmaking_match_users` ( `matchmaking_match_id` bigint (20) unsigned NOT NULL , `user_id` int (10) unsigned NOT NULL , `team` tinyint(1) unsigned NOT NULL , `accepted` tinyint(1) unsigned NOT NULL DEFAULT 0, PRIMARY KEY (`matchmaking_match_id`,`user_id`), UNIQUE KEY `mmu_user_id` (`user_id`), CONSTRAINT `matchmaking_match_users_ibfk_1` FOREIGN KEY (`matchmaking_match_id`) REFERENCES `matchmaking_match` (`id`) ON DELETE CASCADE ON UPDATE CASCADE , CONSTRAINT `matchmaking_match_users_ibfk_2` FOREIGN KEY (`user_id`) REFERENCES `users` (`id`) ON DELETE CASCADE ON UPDATE CASCADE ) ENGINE=InnoDB DEFAULT CHARSET=utf8 | + -------------------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+ 1 row in set (0.00 sec)   MariaDB [esportal]> select * from matchmaking_match_users where matchmaking_match_id not in ( select id from matchmaking_match); + ----------------------+-----------+------+----------+ | matchmaking_match_id | user_id | team | accepted | + ----------------------+-----------+------+----------+ | 146803 | 146613110 | 1 | 1 | | 146803 | 155148690 | 2 | 1 | | 146803 | 180757106 | 1 | 1 | | 146803 | 244313752 | 2 | 0 | | 146803 | 273445176 | 2 | 0 | | 146803 | 279060114 | 2 | 1 | | 146803 | 279463940 | 1 | 1 | | 146803 | 327802118 | 1 | 1 | | 146803 | 405506430 | 2 | 0 | + ----------------------+-----------+------+----------+ 9 rows in set (0.00 sec)   MariaDB [esportal]> delete from matchmaking_match_users where matchmaking_match_id=146803; Query OK, 9 rows affected (0.00 sec)

Asmir Mustafic added a comment - 2018-10-10 08:21 - edited I'm facing the same issue with 10.2.11 As a temporary solution I have created a cronjob that daily sets to null the columns having orphan values. But now that we have introduced a slave server, we have the same issue also on the slave... and for now we have also periodically to skip replication errors...

Asmir Mustafic added a comment - 2018-10-10 08:30 - edited Here are my create tables: CREATE TABLE `users` ( `id` int(11) unsigned NOT NULL AUTO_INCREMENT, `nickname` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL, `main_picture_id` int(11) DEFAULT NULL, PRIMARY KEY (`id`), KEY `users_main_picture_id_index` (`main_picture_id`) ) ENGINE=InnoDB AUTO_INCREMENT=5903615 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci";     CREATE TABLE `users_pictures` ( `id` int(11) NOT NULL AUTO_INCREMENT, `user_id` int(11) unsigned NOT NULL, PRIMARY KEY (`id`), KEY `user_id` (`user_id`), CONSTRAINT `users_pictures_users_user_id_fk` FOREIGN KEY (`user_id`) REFERENCES `users` (`id`) ON DELETE CASCADE ON UPDATE CASCADE ) ENGINE=InnoDB AUTO_INCREMENT=7561551 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci"; From time to time (daily), main_picture_id contains IDs that do not exists in the users_pictures table.

Asmir Mustafic added a comment - 2018-10-10 08:34 - edited CHECK TABLE on both tables did not report any error

Marko Mäkelä added a comment - 2019-02-21 11:13 Samman , goetas , sorry, I only became aware of this report now. Can you please confirm if you are still having the problem with more recent MariaDB? I believe that MariaDB 10.2.13 should have fixed this .