目录
- 故障现象
- 问题排查
- 问题解决
- 问题复现
- 环境信息
- 操作步骤
- 原理分析
- 改进建议
- 关于 SQLE
- SQLE 获取
故障现象
某客户反馈,使用 mysqldump 搭建从库,启动复制后,复制报错:
Could not execute Write_rows event on table xxx; Duplicate entry 'xxx' for key 'PRIMARY'。
客户使用的命令(看起来没啥问题)。
-- 主库备份 shell> mysqldump -uroot -pxxx --master-data=2 --single-transaction -A --routines --events --triggers >/tmp/xxx.sql -- 从服务器还原备份并启动复制 mysql>reset master; mysql>reset slave all; mysql>source /tmp/xxx.sql ; mysql&pythongt;change master to master_host='xxx',master_port=3306,master_user='xxx',master_password='xxx',master_auto_position=1; mysql>start slave;
问题排查
查看复制报错表的表结构,发现表的存储引擎为 MyISAM 引擎。
根据客户反馈,表访问比较频繁,mysqldump --single-transaction
选项,只能保证 InnoDB 引擎表备份的一致性,无法保证 MyISAM 引擎表备份的一致性,问题可能就出在这。
问题解决
修改表的存储引擎为 InnoDB 后,重新备份恢复,可以正常搭建从库。
问题复现
下面我们来复现一下该问题。
环境信息
操作系统 | Centos linux release 7.5.1804 (Core) |
版本 | MySQL 5.7.25 |
主库 | 10.186.60.187 |
从库 | 10.186.60.37 |
主从 | 开启 GTID |
操作步骤
在主库,使用 Sysbench 造一张 1000w 数据的 InnoDB 引擎的表 testdb_innodb.sbtest1
(造 1000w 数据主要目的是让备份 InnoDB 引擎表的时间拉长)。
shell> sysbench /usr/share/sysbench/tests/include/oltp_legacy/oltp.Lua \ --mysql-host=10.186.60.187 --mysql-port=3307 --mysql-user=root \ --mysql-password=1 --mysql-db=testdb_innodb --oltp-table-size=10000000 --oltp-tables-count=1 --threads=4 --report-interval=3 prepare -- 表结构如下 mysql> show create table testdb_innodb.sbtest1; CREATE TABLE `sbtest1` ( `id` int(10) unsigned NOT NULL AUTO_INCREMENT, `k` int(10) unsigned NOT NULL DEFAULT '0', `c` char(120) COLLATE utf8mb4_bin NOT NULL DEFAULT '', `pad` char(60) COLLATE utf8mb4_bin NOT NULL DEFAULT '', PRIMARY KEY (`id`), KEY `k_1` (`k`) ) ENGINE=InnoDB AUTO_INCREMENT=10000001 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin -- 表总行数如下: mysql> select count(*) from testdb_innodb.sbtest1; +----------+ | count(*) | +----------+ | 10000000 | +----------+
在主库,造一张 MyISAM 引擎的表 testdb_myisam.sbtest2
。
-- 表结构如下: mysql> CREATE TABLE testdb_myisam.`sbtest2` ( `id` int(10) unsigned NOT NULL AUTO_INCREMENT, `k` int(10) unsigned NOT NULL DEFAULT '0', `c` char(120) COLLATE utf8mb4_bin NOT NULL DEFAULT '', `pad` char(60) COLLATE utf8mb4_bin NOT NULL编程 DEFAULT '', PRIMARY KEY (`id`), KEY `k_1` (`k`) ) ENGINE=myisam AUTO_INCREMENT=1 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin
在主库,开始 mysqldump 逻辑备份,并在执行备份 testdb_innodb.sbtest1
期间(备份的顺序:先备份 testdb_innodb
库),往 testdb_myisam.sbtest2
表插入一条数据。
-- 执行 mysqldump 备份 shell> /data/mysql/base/5.7.25/bin/mysqldump -h10.186.60.187 -P3307 -uroot -p1 --master-data=2 --single-transaction -A --routines --events --triggers >/tmp/dump.sql -- 执行备份 testdb_innodb.sbtest1 期间,往 testdb_myisam.sbtest2 表插入一条数据 mysql> insert into testdb_myisam.`sbtest2`(k,c,pad) values(2,'myisam','myisam'); -- 通过 MySQL general_log 观察备份情况 2023-07-11T16:15:50.900581+08:00 2692 Connect root@10.186.60.187 on using TCP/IP 2023-07-11T16:15:50.901124+08:00 2692 Query /*!40100 SET @@SQL_MODE='' */ 2023-07-11T16:15:50.901529+08:00 2692 Query /*!40103 SET TIME_ZONE='+00:00' */ 2023-07-11T16:15:50.901743+08:00 2692 Query FLUSH /*!40101 LOCAL */ TABLES 2023-07-11T16:15:50.938083+08:00 2692 Query FLUSH TABLES WITH READ LOCK 2023-07-11T16:15:50.938281+08:00 2692 Query SET SESSION TRANSACTION ISOLATION LEVEL REPEATABLE READ 2023-07-11T16:15:50.938410+08:00 2692 Query START TRANSACTION /*!40100 WITH CONSISTENT SNAPSHOT */ 2023-07-11T16:15:50.938678+08:00 2692 Query SHOW VARIABLES LIKE 'gtid\_mode' 2023-07-11T16:15:50.980335+08:00 2692 Query SELECT @@GLOBAL.GTID_EXECUTED 2023-07-11T16:15:50.980566+08:00 2692 Query SHOW MASTER STATUS 2023-07-11T16:15:50.980758+08:00 2692 Query UNLOCK TABLES ...略 2023-07-11T16:15:51.541911+08:00 2692 Init DB testdb_innodb 2023-07-11T16:15:51.542012+08:00 2692 Query SHOW CREATE DATABASE IF NOT EXISTS `testdb_innodb` 2023-07-11T16:15:51.542139+08:00 2692 Query SAVEPOINT sp 2023-07-11T16:15:51.542224+08:00 2692 Query show tables 2023-07-11T16:15:51.542405+08:00 2692 Query show table status like 'sbtest1' 2023-07-11T16:15:51.543353+08:00 2692 Query SET SQL_QUOTE_SHOW_CREATE=1 2023-07-11T16:15:51.543467+08:00 2692 Query SET SESSION character_set_results = 'binary' 2023-07-11T16:15:51.543548+08:00 2692 Query show create table `sbtest1` 2023-07-11T16:15:51.543729+08:00 2692 Query SET SESSION character_set_results = 'utf8' 2023-07-11T16:15:51.543837+08:00 2692 Query show fields from `sbtest1` 2023-07-11T16:15:51.544172+08:00 2692 Query show fields from `sbtest1` 2023-07-11T16:15:51.544477+08:00 2692 Query SELECT /*!40001 SQL_NO_CA编程客栈CHE */ * FROM `sbtest1` 2023-07-11T16:15:57.603435+08:00 2683 Query insert into testdb_myisam.`sbtest2`(k,c,pad) values(2,'myisam','myisam') 2023-07-11T16:16:27.456357+08:00 2692 Query SET SESSION character_set_results = 'binary' 2023-07-11T16:16:27.471239+08:00 2692 Query use `testdb_innodb` 2023-07-11T16:16:27.471589+08:00 2692 Query select @@collation_database 2023-07-11T16:16:27.472065+08:00 2692 Query SHOW TRIGGERS LIKE 'sbtest1' 2023-07-11T16:16:27.506025+08:00 2692 Query SET SESSION character_set_results = 'utf8' 2023-07-11T16:16:27.506225+08:00 2692 Query ROLLBACK TO SAVEPOINT sp 2023-07-11T16:16:27.506383+08:00 2692 Query RELEASE SAVEPOINT sp 2023-07-11T16:16:27.506538+08:00 2692 Query show events 2023-07-11T16:16:27.507226+08:00 2692 Query use `testdb_innodb` 2023-07-11T16:16:27.507346+08:00 2692 Query select @@collation_database 2023-07-11T16:16:27.507457+08:00 2692 Query SET SESSION character_set_results = 'binary' 2023-07-11T16:16:27.507629+08:00 2692 Query SHOW FUNCTION STATUS WHERE Db = 'testdb_innodb' 2023-07-11T16:16:27.621194+08:00 2692 Query SHOW PROCEDURE STATUS WHERE Db = 'testdb_innodb' 2023-07-11T16:16:27.622726+08:00 2692 Query SET SESSION character_set_results = 'utf8' 2023-07-11T16:16:27.622900+08:00 2692 I编程客栈nit DB testdb_myisam 2023-07-11T16:16:27.623005+08:00 2692 Query SHOW CREATE DATABASE IF NOT EXISTS `testdb_myisam` 2023-07-11T16:16:27.623102+08:00 2692 Query SAVEPOINT sp 2023-07-11T16:16:27.623211+08:00 2692 Query show tables 2023-07-11T16:16:27.623566+08:00 2692 Query show table status like 'sbtest2' 2023-07-11T16:16:27.624197+08:00 2692 Query SET SQL_QUOTE_SHOW_CREATE=1 2023-07-11T16:1python6:27.624314+08:00 2692 Query SET SESSION character_set_results = 'binary' 2023-07-11T16:16:27.624401+08:00 2692 Query show create table `sbtest2` 2023-07-11T16:16:27.624518+08:00 2692 Query SET SESSION character_set_results = 'utf8' 2023-07-11T16:16:27.624605+08:00 2692 Query show fields from `sbtest2` 2023-07-11T16:16:27.625027+08:00 2692 Query show fields from `sbtest2` 2023-07-11T16:16:27.625391+08:00 2692 Query SELECT /*!40001 SQL_NO_CACHE */ * FROM `sbtest2` 2023-07-11T16:16:27.636073+08:00 2692 Query SET SESSION character_set_results = 'binary' 2023-07-11T16:16:27.636213+08:00 2692 Query use `testdb_myisam` 2023-07-11T16:16:27.636317+08:00 2692 Query select @@collation_database 2023-07-11T16:16:27.636429+08:00 2692 Query SHOW TRIGGERS LIKE 'sbtest2' 2023-07-11T16:16:27.636923+08:00 2692 Query SET SESSION character_set_results = 'utf8' 2023-07-11T16:16:27.637034+08:00 2692 Query ROLLBACK TO SAVEPOINT sp 2023-07-11T16:16:27.637116+08:00 2692 Query RELEASE SAVEPOINT sp 2023-07-11T16:16:27.637195+08:00 2692 Query show events 2023-07-11T16:16:27.637517+08:00 2692 Query use `testdb_myisam` 2023-07-11T16:16:27.637631+08:00 2692 Query select @@collation_database 2023-07-11T16:16:27.637741+08:00 2692 Query SET SESSION character_set_results = 'binary' 2023-07-11T16:16:27.637839+08:00 2692 Query SHOW FUNCTION STATUS WHERE Db = 'testdb_myisam' 2023-07-11T16:16:27.639206+08:00 2692 Query SHOW PROCEDURE STATUS WHERE Db = 'testdb_myisam' 2023-07-11T16:16:27.640377+08:00 2692 Query SET SESSION character_set_results = 'utf8' 2023-07-11T16:16:27.663274+08:00 2692 Quit
在从服务器,使用上述 mysqldump 逻辑备份文件执行恢复,搭建从库。
-- 从库查看数据库 mysql> show databases; +--------------------+ | Database | +--------------------+ | information_schema | | mysql | | performance_schema | | sys | +--------------------+ -- 清空从库 binlog 和 gtid 信息 mysql> reset master; -- 查看确认 mysql> show master status\G; *************************** 1. row *************************** File: mysql-bin.000001 Position: 154 Binlog_Do_DB: Binlog_Ignore_DB: Executed_Gtid_Set: 1 row in set (0.00 sec) -- 执行 mysqldump 逻辑备份文件恢复 mysql> source /tmp/dump.sql; -- 建立复制,并启动复制 mysql> change master to MASTER_HOST='10.186.60.187',MASTER_PORT=3307,master_user='repl',master_password='1',MASTER_AUTO_POSITION=1; mysql> start slave; -- 查看复制状态 mysql> show slave status\G; *************************** 1. row *************************** Slave_IO_State: Waiting for master to send event Master_Host: 10.186.60.187 Master_User: repl Master_Port: 3307 Connect_Retry: 60 Master_Log_File: mysql-bin.000015 Read_Master_Log_Pos: 190088135 Relay_Log_File: mysql-relay.000002 Relay_Log_Pos: 414 Relay_Master_Log_File: mysql-bin.000015 Slave_IO_Running: Yes Slave_SQL_Running: No Replicate_Do_DB: Replicate_Ignore_DB: Replicate_Do_Table: Replicate_Ignore_Table: Replicate_Wild_Do_Table: Replicate_Wild_Ignore_Table: Last_Errno: 1062 Last_Error: Coordinator stopped because there were error(s) in the worker(s). The most recent failure being: Worker 1 failed executing transaction '19112042-1f97-11ee-bf09-02000aba3cbb:3747' at master log mysql-bin.000015, end_log_pos 190087781. See error log and/or performance_schema.replication_applier_status_by_worker table for more details about this failure or others, if any. Skip_Counter: 0 Exec_Master_Log_Pos: 190087413 Relay_Log_Space: 1339 Until_Condition: None Until_Log_File: Until_Log_Pos: 0 Master_SSL_Allowed: No Master_SSL_CA_File: Master_SSL_CA_Path: Master_SSL_Cert: Master_SSL_Cipher: Master_SSL_Key: Seconds_Behind_Master: NULL Master_SSL_Verify_Server_Cert: No Last_IO_Errno: 0 Last_IO_Error: Last_SQL_Errno: 1062 Last_SQL_Error: Coordinator stopped because there were error(s) in the worker(s). The most recent failure being: Worker 1 failed executing transaction '19112042-1f97-11ee-bf09-02000aba3cbb:3747' at master log mysql-bin.000015, end_log_pos 190087781. See error log and/or performance_schema.replication_applier_status_by_worker table for more details about this failure or others, if any. Replicate_Ignore_Server_Ids: Master_Server_Id: 629181509 Master_UUID: 19112042-1f97-11ee-bf09-02000aba3cbb Master_Info_File: mysql.slave_master_info SQL_Delay: 0 SQL_Remaining_Delay: NULL Slave_SQL_Running_State: Master_Retry_Count: 86400 Master_Bind: Last_IO_Error_Timestamp: Last_SQL_Error_Timestamp: 230711 17:03:01 Master_SSL_Crl: Master_SSL_Crlpath: Retrieved_Gtid_Set: 19112042-1f97-11ee-bf09-02000aba3cbb:3747-3748 Executed_Gtid_Set: 19112042-1f97-11ee-bf09-02000aba3cbb:1-3746 Auto_Position: 1 Replicate_Rewrite_DB: Channel_Name: Master_TLS_Version: 1 row in set (0.00 sec) -- 查看复制具体报错内容 mysql> select * from performance_schema.replication_applier_status_by_worker\G; *************************** 1. row *************************** CHANNEL_NAME: WORKER_ID: 1 THREAD_ID: NULL SERVICE_STATE: OFF LAST_SEEN_TRANSACTION: 19112042-1f97-11ee-bf09-02000aba3cbb:3747 LAST_ERROR_NUMBER: 1062 LAST_ERROR_MESSAGE: Worker 1 failed executing transaction '19112042-1f97-11ee-bf09-02000aba3cbb:3747' at master log mysql-bin.000015, end_log_pos 190087781; Could not execute Write_rows event on table testdb_myisam.sbtest2; Duplicate entry '2' for key 'PRIMARY', Error_code: 1062; handler error HA_ERR_FOUND_DUPP_KEY; the event's master log FIRST, end_log_pos 190087781 LAST_ERROR_TIMESTAMP: 2023-07-11 17:03:01
原理分析
- 当 mysqldump 开始备份,并获取一致性位点后,
UNLOCK TABLES
前,记为 T1 时刻。 - 备份 InnoDB 表完成(假设先备份 InnoDB 表),记为 T2 时刻。
- 备份 MyISAM 引擎表完成,记为 T3 时刻。
- 在 T1 和 T2 之间,如果 MyISAM 引擎表有 INSERT 操作,会有 binlog 产生,mysqldump 也会把 T1 到 T2 之间对 MyISAM 引擎表的 INSERT 数据备份下来。
- 这样就产生了,启动复制后,由于 SQL 线程会回放 T1 到 T2 期间的 binlog,而这部分数据已经在备份文件里了,并恢复到从库了,导致 SQL 线程回放报重复键的问题。
- 使用该选项时:
mysqldump --single-transaction
获取一致性备份只适用于 InnoDB 引擎,对于 InnoDB 引擎表的备份,获取的是 T1 时刻的快照,对于非 InnoDB 引擎表的备份,获取的是当前最新数据。
改进建议
- 把业务库的非 InnoDB 引擎表,修改为 InnoDB,重新备份后搭建从库( 修改表的存储引擎开销较大,需要考虑改存储引擎对在线业务的影响,适合表可以改为 InnoDB 引擎的情况)。
- 改用 Xtrabacku
p 备份工具。如果非 InnoDB 的表比较大,备份 MyISAM 引擎期间, 备份线程持有实例的全局读锁(FLUSH TABLES WITH READ LOCK)时间将增加,将影响数据库可用性,选择业务低峰时执行。(适合短时间内无法修改表存储引擎的情况)。
更多技术文章,请访问:https://www.jb51.net/
关于 SQLE
爱可生开源社区的 SQLE 是一款面向数据库使用者和管理者,支持多场景审核,支持标准化上线流程,原生支持 MySQL 审核且数据库类型可扩展的 SQL 审核工具。
SQLE 获取
类型 | 地址 |
---|---|
版本库 | https://github.com/actiontech/sqle |
文档 | https://actiontech.github.io/sqle-docs/ |
发布信息 | https://github.com/actiontech/sqle/releases |
数据审核插件开发文档 | https://actiontech.github.io/sqle-docs/docs/dev-manual/plugin... |
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