故障描述
percona5.6，mysqldump全備份，導入備份數據時報錯Duplicate entry 'hoc_log99-item_log_27-PRIMARY-n_diff_pfx01' for key 'PRIMARY'
故障原因
查看了下這個主鍵應該是MySQL系統庫下的系統表innodb_index_stats
| mysql> show create table innodb_index_stats/G*************************** 1. row *************************** Table: innodb_index_statsCreate Table: CREATE TABLE `innodb_index_stats` ( `database_name` varchar(64) COLLATE utf8_bin NOT NULL, `table_name` varchar(64) COLLATE utf8_bin NOT NULL, `index_name` varchar(64) COLLATE utf8_bin NOT NULL, `last_update` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP, `stat_name` varchar(64) COLLATE utf8_bin NOT NULL, `stat_value` bigint(20) unsigned NOT NULL, `sample_size` bigint(20) unsigned DEFAULT NULL, `stat_description` varchar(1024) COLLATE utf8_bin NOT NULL, PRIMARY KEY (`database_name`,`table_name`,`index_name`,`stat_name`)) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_bin STATS_PERSISTENT=01 row in set (0.00 sec)mysql> select * from innodb_index_stats where database_name='hoc_log99' and table_name='item_log_27' and stat_name='n_diff_pfx01' and index_name='PRIMARY';+---------------+-------------+------------+---------------------+--------------+------------+-------------+------------------+| database_name | table_name | index_name | last_update | stat_name | stat_value | sample_size | stat_description |+---------------+-------------+------------+---------------------+--------------+------------+-------------+------------------+| hoc_log99 | item_log_27 | PRIMARY | 2016-10-07 18:44:06 | n_diff_pfx01 | 823672 | 20 | redid |+---------------+-------------+------------+---------------------+--------------+------------+-------------+------------------+1 row in set (0.00 sec) |
再查看下我當時的備份文件sql的記錄，發現再導入這個表之前是會重建表的，排除了再導入這個表之前，有item_log_27 表的操作記錄進了innodb_index_stats的可能。
| -- Table structure for table `innodb_index_stats`DROP TABLE IF EXISTS `innodb_index_stats`;CREATE TABLE `innodb_index_stats` (-- Dumping data for table `innodb_index_stats`LOCK TABLES `innodb_index_stats` WRITE;/*!40000 ALTER TABLE `innodb_index_stats` DISABLE KEYS */; |
于是我又查看了下最近的binlog記錄，發現確實有重建這個表的操作
| DROP TABLE IF EXISTS `innodb_index_stats` /* generated by server */CREATE TABLE `innodb_index_stats` (/*!40000 ALTER TABLE `innodb_index_stats` DISABLE KEYS */ |
結論
mysql 5.6的bug，也有其他同行遇到了一樣的錯誤
https://www.percona.com/forums/questions-discussions/mysql-and-percona-server/31971-mysql-innodb_index_stats-duplication-entry-error-on-restore
https://bugs.mysql.com/bug.PHP?id=71814
解決辦法
1 mysqldump添加參數忽略這個表的備份
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