5.7中新mysqlbinlog新增加了rewrite-db选项，在binlog_format=row时，可以转换库的名称：

在binlog_format=row时，不跨库
flush logs;
use tt;

mysql> create table c(id int);
Query OK, 0 rows affected (0.02 sec)

mysql> insert into c values (1);
Query OK, 1 row affected (0.01 sec)

mysql> commit;
Query OK, 0 rows affected (0.00 sec)

mysqlbinlog --rewrite-db='tt->test' 1.000002 > /tmp/a.sql
mysqlbinlog 1.000002 > /tmp/b.sql

把/tmp/a.sql /tmp/b.sql进行对比
diff /tmp/a.sql /tmp/b.sql
20c20
< use `test`/*!*/;
---
> use `tt`/*!*/;
41c41
< #160531 21:57:41 server id 1 end_log_pos 488 CRC32 0x1907f678 Table_map: `test`.`c` mapped to number 110
---
> #160531 21:57:41 server id 1 end_log_pos 488 CRC32 0x1907f678 Table_map: `tt`.`c` mapped to number 110
46c46
< VZhNVxMBAAAALAAAAOgBAAAAAG4AAAAAAAEABHRlc3QAAWMAAQMAAXj2Bxk=
---
> VZhNVxMBAAAAKgAAAOgBAAAAAG4AAAAAAAEAAnR0AAFjAAEDAAF49gcZ

在binlog_format=statement时，不跨库

mysql> show variables like '%binlog_f%';
+---------------+-----------+
| Variable_name | Value |
+---------------+-----------+
| binlog_format | STATEMENT |
+---------------+-----------+
mysql> use tt;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed
mysql> drop table c;
Query OK, 0 rows affected (0.00 sec)
mysql> flush logs;
Query OK, 0 rows affected (0.01 sec)
mysql> create table c(id int);
Query OK, 0 rows affected (0.02 sec)

mysql> insert into c values (1);
Query OK, 1 row affected (0.00 sec)

diff /tmp/a.sql /tmp/b.sql
20c20
< use `test`/*!*/;
---
> use `tt`/*!*/;

看起来也是可以的。

但是对于在一个库中执行另外一个库中的操作 binlog_format=statement就不行了

mysql> show variables like '%binlog_f%';
+---------------+-----------+
| Variable_name | Value |
+---------------+-----------+
| binlog_format | STATEMENT |
+---------------+-----------+
mysql> flush logs;
Query OK, 0 rows affected (0.00 sec)

mysql> create database song;
Query OK, 1 row affected (0.01 sec)

mysql> create table song.a(id int);
Query OK, 0 rows affected (0.02 sec)

mysql> insert into song.a values (1);
Query OK, 1 row affected (0.00 sec)
[root@10-13-38-7data]# mysqlbinlog --rewrite-db='song->test' 1.000004 > /tmp/song.sql
[root@10-13-38-7data]# mysqlbinlog 1.000004 > /tmp/song_no.sql
[root@10-13-38-7data]# diff /tmp/song.sql /tmp/song_no.sql

结果是一样的，所以这时的转换是没有效果的
当binlog_format=row时，跨库
mysql> drop database song;
Query OK, 1 row affected (0.00 sec)

mysql> flush logs;
Query OK, 0 rows affected (0.00 sec)

mysql> show variables like '%binlog_f%';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| binlog_format | ROW |
+---------------+-------+
1 row in set (0.00 sec)

mysql> create database song;
Query OK, 1 row affected (0.00 sec)

mysql> create table song.a(id int);
Query OK, 0 rows affected (0.02 sec)

mysql> insert into song.a values (1);
Query OK, 1 row affected (0.00 sec)

[root@10-13-38-7data]# mysqlbinlog --rewrite-db='song->test' 1.000005 > /tmp/song.sql
[root@10-13-38-7data]# mysqlbinlog 1.000005 > /tmp/song_no.sql
[root@10-13-38-7data]# diff /tmp/song.sql /tmp/song_no.sql
48c48
< #160531 22:19:53 server id 1 end_log_pos 652 CRC32 0xb9ccbd3d Table_map: `test`.`a` mapped to number 114
---
> #160531 22:19:53 server id 1 end_log_pos 652 CRC32 0xb9ccbd3d Table_map: `song`.`a` mapped to number 114
53c53
< iZ1NVxMBAAAALAAAAIwCAAAAAHIAAAAAAAEABHRlc3QAAWEAAQMAAT29zLk=
---
> iZ1NVxMBAAAALAAAAIwCAAAAAHIAAAAAAAEABHNvbmcAAWEAAQMAAT29zLk=