Slave被误写入数据如何恢复到主库

背景

在GreatSQL主从复制环境中,有时候可能会出现一些误操作,将本应该写入到主库的数据写入到了从库,导致主从数据不一致,影响数据同步。是否可以将写入从库的数据同步写入主库呢?

测试环境

角色IP地址数据库开放端口版本
主库192.168.137.1793308GreatSQL 8.0.32
从库192.168.137.1803308GreatSQL 8.0.32

复制链路:

greatsql> show slave status\G;
*************************** 1. row ***************************
 Slave_IO_State: Waiting for source to send event
 Master_Host: 192.168.137.179
 Master_User: root
 Master_Port: 3308
 Connect_Retry: 60
 Master_Log_File: binlog.000001
 Read_Master_Log_Pos: 157
 Relay_Log_File: oracle_dts-relay-bin.000002
 Relay_Log_Pos: 367
 Relay_Master_Log_File: binlog.000001
 Slave_IO_Running: Yes
 Slave_SQL_Running: Yes

表数据

主库

greatsql> select * from dept;
+--------+------------+----------+
| DEPTNO | DNAME | LOC |
+--------+------------+----------+
| 10 | ACCOUNTING | NEW YORK |
| 20 | RESEARCH | DALLAS |
| 30 | SALES | CHICAGO |
| 40 | OPERATIONS | BOSTON |
| 60 | it | 成都 |
+--------+------------+----------+
5 rows in set (0.00 sec)
greatsql> insert into dept select 70,'IT','CTU';
Query OK, 1 row affected (0.01 sec)
Records: 1 Duplicates: 0 Warnings: 0
greatsql> commit;
Query OK, 0 rows affected (0.00 sec)

从库

greatsql> select * from dept;
+--------+------------+----------+
| DEPTNO | DNAME | LOC |
+--------+------------+----------+
| 10 | ACCOUNTING | NEW YORK |
| 20 | RESEARCH | DALLAS |
| 30 | SALES | CHICAGO |
| 40 | OPERATIONS | BOSTON |
| 60 | it | 成都 |
| 70 | IT | CTU |
+--------+------------+----------+
6 rows in set (0.00 sec)

主库写入的数据正常同步到从库

在从库写入数据

greatsql> insert into dept select 80,'IT','SZ';
Query OK, 1 row affected (0.01 sec)
Records: 1 Duplicates: 0 Warnings: 0
greatsql> insert into dept select 90,'SALES','SZ';
Query OK, 1 row affected (0.01 sec)
Records: 1 Duplicates: 0 Warnings: 0

从库数据

greatsql> select * from dept;
+--------+------------+----------+
| DEPTNO | DNAME | LOC |
+--------+------------+----------+
| 10 | ACCOUNTING | NEW YORK |
| 20 | RESEARCH | DALLAS |
| 30 | SALES | CHICAGO |
| 40 | OPERATIONS | BOSTON |
| 60 | it | 成都 |
| 70 | IT | CTU |
| 80 | IT | SZ |
| 90 | SALES | SZ |
+--------+------------+----------+
8 rows in set (0.00 sec)

主库数据

greatsql> select * from dept;
+--------+------------+----------+
| DEPTNO | DNAME | LOC |
+--------+------------+----------+
| 10 | ACCOUNTING | NEW YORK |
| 20 | RESEARCH | DALLAS |
| 30 | SALES | CHICAGO |
| 40 | OPERATIONS | BOSTON |
| 60 | it | 成都 |
| 70 | IT | CTU |
+--------+------------+----------+
6 rows in set (0.01 sec)

此时从库写入的数据在主库中并没有出现

解析从库的二进制日志

$ mysqlbinlog -vv --base64-output=decode-rows binlog.000002>b002.sql
 BEGIN
/*!*/;
#at 354
#240221 16:10:25 server id 18001 end_log_pos 416 CRC32 0xcc81584b Table_map: `scott`.`dept` mapped to number 101
#has_generated_invisible_primary_key=0
#at 416
#240221 16:10:25 server id 18001 end_log_pos 462 CRC32 0x5149e38a Write_rows: table id 101 flags:
 STMT_END_F
###INSERT INTO `scott`.`dept`
###SET
###@1=80 /* INT meta=0 nullable=0 is_null=0 */
###@2='IT' /* VARSTRING(56) meta=56 nullable=1 is_null=0 */
###@3='SZ' /* VARSTRING(52) meta=52 nullable=1 is_null=0 */
#at 462
#240221 16:10:25 server id 18001 end_log_pos 493 CRC32 0xab795e4a Xid = 34

可以看到写入的从库写入的数据在 binlog.000002,我们可以通过 grep 从库的 server id 确定日志文件中有没有在从库写入的数据。

复制从库日志到主库

$ scp binlog.000002 192.168.137.179:/tmp/
Warning: Permanently added '192.168.137.179' (ECDSA) to the list of known hosts.
root@192.168.137.179's password: 
binlog.000002 100% 836 1.1MB/s 00:00 

应用从库的二进制日志

应用从库的日志到主库

$ mysqlbinlog binlog.000002|mysql -uroot -p -h127.1 -P3308

主库应用从库二进制日志时,从库二进制日志信息未发生变化

greatsql> show binary logs;
+---------------+-----------+-----------+
| Log_name | File_size | Encrypted |
+---------------+-----------+-----------+
| binlog.000001 | 498 | No |
| binlog.000002 | 836 | No |
| binlog.000003 | 237 | No |
+---------------+-----------+-----------+
3 rows in set (0.00 sec)

主从复制链路状态正常

greatsql> show slave status\G;
*************************** 1. row ***************************
 Slave_IO_State: Waiting for source to send event
 Master_Host: 192.168.137.179
 Master_User: root
 Master_Port: 3308
 Connect_Retry: 60
 Master_Log_File: binlog.000001
 Read_Master_Log_Pos: 1059
 Relay_Log_File: oracle_dts-relay-bin.000002
 Relay_Log_Pos: 1269
 Relay_Master_Log_File: binlog.000001
 Slave_IO_Running: Yes
 Slave_SQL_Running: Yes

可以看到主库在应用从库产生的二进制日志时,从库没有重复应用这些二进制日志(By default, the replication I/O (receiver) thread does not write binary log events to the relay log if they have the replica's server ID (this optimization helps save disk usage). ),出现主键冲突,导致复制状态出错

查看主库数据

greatsql> select * from dept;
+--------+------------+----------+
| DEPTNO | DNAME | LOC |
+--------+------------+----------+
| 10 | ACCOUNTING | NEW YORK |
| 20 | RESEARCH | DALLAS |
| 30 | SALES | CHICAGO |
| 40 | OPERATIONS | BOSTON |
| 60 | it | 成都 |
| 70 | IT | CTU |
| 80 | IT | SZ |
| 90 | SALES | SZ |
+--------+------------+----------+
8 rows in set (0.00 sec)

后续测试,主库写入数据可正常同步到从库。


Enjoy GreatSQL 😃

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作者:GreatSQL原文地址:https://www.cnblogs.com/greatsql/p/18033738

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