多源复制遇到CREATE USER FAILED错误

MySQL Multi-Source Replication enables a replication slave to receive transactions from multiple sources simultaneously. Multi-source replication does not implement any conflict detection or resolution when applying the transactions, and those tasks are left to the application if required.

一、问题描述

多源复制，从库在开启复制之前，执行change replication filter replicate_ignore_db=(mysql); 按理应该忽略了mysql库的同步，为什么开启复制之后报错

Last_Error: Error 'Operation CREATE USER failed for 'repl'@'192.168.85.%'' on query. Default database: ''. Query: 'CREATE USER 'repl'@'192.168.85.%' IDENTIFIED WITH 'mysql_native_password' AS '*A424E797037BF97C19A2E88CF7891C5C2038C039''

首先怀疑使用了statement格式的日志(binlog_format='STATEMENT')，提问者没有说binlog_format。按照一贯思维，如果binlog_format='ROW'，它会检查变更数据所在的database是否匹配过滤选项；如果binlog_format='STATEMENT'，它会检查default database(use dbname)是否匹配过滤选项。
第一个推断：binlog_format='STATEMENT'，create user语句不是在mysql库下运行~

二、验证推断

2.1、create user

为了验证推断，在自己的一主一从环境(Gtid+Row)测试create user语句

# 从库复制过滤
mydba@192.168.85.133,3306 [(none)]> stop slave sql_thread;
Query OK, 0 rows affected (0.01 sec)

mydba@192.168.85.133,3306 [(none)]> change replication filter replicate_ignore_db=(mysql);
Query OK, 0 rows affected (0.00 sec)

mydba@192.168.85.133,3306 [(none)]> start slave sql_thread;
Query OK, 0 rows affected (0.01 sec)


# 主库Rotate日志
mydba@192.168.85.132,3306 [replcrash]> flush binary logs;
Query OK, 0 rows affected (0.12 sec)

mydba@192.168.85.132,3306 [replcrash]> show master status;
+------------------+----------+--------------+------------------+----------------------------------------------+
| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set                            |
+------------------+----------+--------------+------------------+----------------------------------------------+
| mysql-bin.000108 |      194 |              |                  | 8ab82362-9c37-11e7-a858-000c29c1025c:1-69347 |
+------------------+----------+--------------+------------------+----------------------------------------------+
1 row in set (0.00 sec)

mydba@192.168.85.132,3306 [replcrash]> select user,host from mysql.user;
+---------------+--------------+
| user          | host         |
+---------------+--------------+
| monitor       | %            |
| mydba         | 192.168.85.% |
| repl          | 192.168.85.% |
| restoree      | 192.168.85.% |
| resolve       | db%.zst.com  |
| mysql.session | localhost    |
| mysql.sys     | localhost    |
| root          | localhost    |
| zst           | localhost    |
+---------------+--------------+
9 rows in set (0.00 sec)


# 从库Rotate日志
mydba@192.168.85.133,3306 [replcrash]> flush logs;
Query OK, 0 rows affected (0.07 sec)

mydba@192.168.85.133,3306 [replcrash]> show master status;
+------------------+----------+--------------+------------------+------------------------------------------------------------------------------------------+
| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set                                                                        |
+------------------+----------+--------------+------------------+------------------------------------------------------------------------------------------+
| mysql-bin.000021 |      234 |              |                  | 8ab82362-9c37-11e7-a858-000c29c1025c:1-69347,
93f69708-9c39-11e7-b7f8-000c2900c99c:1-284 |
+------------------+----------+--------------+------------------+------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

mydba@192.168.85.133,3306 [replcrash]> select user,host from mysql.user;
+---------------+--------------+
| user          | host         |
+---------------+--------------+
| monitor       | %            |
| mydba         | 192.168.85.% |
| repl          | 192.168.85.% |
| restoree      | 192.168.85.% |
| resolve       | db%.zst.com  |
| mysql.session | localhost    |
| mysql.sys     | localhost    |
| root          | localhost    |
| zst           | localhost    |
+---------------+--------------+
9 rows in set (0.02 sec)


# 主库创建新用户(注意这里默认的db是replcrash)
mydba@192.168.85.132,3306 [replcrash]> grant select on sakila.* to 'test'@'%' identified by '1234qwer';
Query OK, 0 rows affected, 1 warning (0.06 sec)

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