从库会update或delete，而且会update成和主库完全相同的一行。这一点主从复制和CDC复制的一样的，都是以主键为查询基准的。复制程序很聪明，如果一张表存在主键的话，update或着delete该表的话，从库的复制程序会通过主键索引查询改行，如果主键返回一行数据就默认是完全相同一行的数据，而不会再去对比其他列值。
update测试：
主库：
mysql> create table test_strict (id int not null primary key,name varchar(10));
Query OK, 0 rows affected (0.02 sec)
mysql> insert into test_strict values(1,'lisi');
Query OK, 1 row affected (0.00 sec)
mysql> select * from test_strict;
+----+------+
| id | name |
+----+------+
| 1 | lisi |
+----+------+
1 row in set (0.00 sec)
从库：
[root@localhost:mytest1]>select * from test_strict;
+----+------------+
| id | name |
+----+------------+
| 1 | zhangsan88 |
+----+------------+
1 row in set (0.00 sec)
主库：
mysql> update test_strict set id=88 where id=1 and name='lisi';
Query OK, 1 row affected (0.00 sec)
Rows matched: 1 Changed: 1 Warnings: 0
mysql>
从库：
[root@localhost:mytest1]>select * from test_strict;
+----+------+
| id | name |
+----+------+
| 88 | lisi |
+----+------+
1 row in set (0.00 sec)
delete测试：
主：
mysql> select * from test_strict;
+----+------+
| id | name |
+----+------+
| 88 | lisi |
+----+------+
1 row in set (0.00 sec)
从：
[root@localhost:mytest1]>select * from test_strict;
+----+-----------+
| id | name |
+----+-----------+
| 88 | zhangsan3 |
+----+-----------+
1 row in set (0.00 sec)
主：
mysql> delete from test_strict where id=88 and name='lisi';
Query OK, 1 row affected (0.00 sec)
从：
[root@localhost:mytest1]>select * from test_strict;
Empty set (0.00 sec)