mysql复制原理与机制一

复制原理:复制需要二进制日志记录数据库上的改变

slave的IO线程复制把master上的Binary log读取到本地的relay log里
SQL线程负责把relay log恢复到数据库数据里

show slave status\G;
  Slave_IO_State: Waiting for master to send event
                  Master_Host: 10.105.7.108
                  Master_User: rep
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: mysql-bin.000004
          Read_Master_Log_Pos: 630
               Relay_Log_File: mysqld-relay-bin.000006
                Relay_Log_Pos: 793
        Relay_Master_Log_File: mysql-bin.000004
             Slave_IO_Running: Yes
            Slave_SQL_Running: Yes

关闭slave的io线程
 stop slave io_thread;
 mysql> show slave status\G;
*************************** 1. row ***************************
               Slave_IO_State:
                  Master_Host: 10.105.7.108
                  Master_User: rep
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: mysql-bin.000004
          Read_Master_Log_Pos: 630
               Relay_Log_File: mysqld-relay-bin.000006
                Relay_Log_Pos: 793
        Relay_Master_Log_File: mysql-bin.000004
             Slave_IO_Running: No
            Slave_SQL_Running: Yes
到master
mysql> show binary logs;
+------------------+-----------+
| Log_name         | File_size |
+------------------+-----------+
| mysql-bin.000001 |       143 |
| mysql-bin.000002 |       367 |
| mysql-bin.000003 |       120 |
| mysql-bin.000004 |       630 |
+------------------+-----------+
4 rows in set (0.00 sec)
日志轮换
mysql> flush logs;
Query OK, 0 rows affected (0.02 sec)

mysql> show binary logs;
+------------------+-----------+
| Log_name         | File_size |
+------------------+-----------+
| mysql-bin.000001 |       143 |
| mysql-bin.000002 |       367 |
| mysql-bin.000003 |       120 |
| mysql-bin.000004 |       677 |
| mysql-bin.000005 |       120 |
+------------------+-----------+
mysql> use hk;
Database changed
mysql> show tables;
+--------------+
| Tables_in_hk |
+--------------+
| test         |
+--------------+
1 row in set (0.01 sec)

mysql> select * from test;
+----+---------------------+
| id | time                |
+----+---------------------+
|  1 | 2017-02-04 10:04:12 |
|  2 | 2017-02-04 13:53:35 |
|  3 | 2017-02-08 19:46:49 |
+----+---------------------+
3 rows in set (0.00 sec)

mysql> insert into test values(4,now());
Query OK, 1 row affected (0.05 sec)

mysql> show binary logs;
+------------------+-----------+
| Log_name         | File_size |
+------------------+-----------+
| mysql-bin.000001 |       143 |
| mysql-bin.000002 |       367 |
| mysql-bin.000003 |       120 |
| mysql-bin.000004 |       677 |
| mysql-bin.000005 |       344 |
+------------------+-----------+
5 rows in set (0.00 sec)

mysql> show binlog events in 'mysql-bin.000005';
+------------------+-----+-------------+-----------+-------------+--------------------------------------------+
| Log_name         | Pos | Event_type  | Server_id | End_log_pos | Info                                       |
+------------------+-----+-------------+-----------+-------------+--------------------------------------------+
| mysql-bin.000005 |   4 | Format_desc |       108 |         120 | Server ver: 5.6.35-log, Binlog ver: 4      |
| mysql-bin.000005 | 120 | Query       |       108 |         203 | BEGIN                                      |
| mysql-bin.000005 | 203 | Query       |       108 |         313 | use `hk`; insert into test values(4,now()) |
| mysql-bin.000005 | 313 | Xid         |       108 |         344 | COMMIT /* xid=110 */                       |
+------------------+-----+-------------+-----------+-------------+--------------------------------------------+
可以看到一件记录到二进制日志里

mysql> select * from test where id=4;
+----+---------------------+
| id | time                |
+----+---------------------+
|  4 | 2017-02-08 20:34:49 |
+----+---------------------+
到从库
Database changed
mysql> select * from test;
+----+---------------------+
| id | time                |
+----+---------------------+
|  1 | 2017-02-04 10:04:12 |
|  2 | 2017-02-04 13:53:35 |
|  3 | 2017-02-08 19:46:49 |
+----+---------------------+
查看此时 Relay_Log_File: mysqld-relay-bin.
mysql> show slave status\G
*************************** 1. row ***************************
               Slave_IO_State:
                  Master_Host: 10.105.7.108
                  Master_User: rep
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: mysql-bin.000004
          Read_Master_Log_Pos: 630
               Relay_Log_File: mysqld-relay-bin.000006
                Relay_Log_Pos: 793
        Relay_Master_Log_File: mysql-bin.000004
             Slave_IO_Running: No
            Slave_SQL_Running: Yes
开启io线程

mysql> start slave io_thread;
Query OK, 0 rows affected (0.01 sec)

mysql> show slave status\G
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 10.105.7.108
                  Master_User: rep
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: mysql-bin.000005
          Read_Master_Log_Pos: 344
               Relay_Log_File: mysqld-relay-bin.000009
                Relay_Log_Pos: 507
        Relay_Master_Log_File: mysql-bin.000005
             Slave_IO_Running: Yes
            Slave_SQL_Running: Yes
发现中继日志发生变化
Relay_Log_File: mysqld-relay-bin.
mysql>  select * from test where id=4;
+----+---------------------+
| id | time                |
+----+---------------------+
|  4 | 2017-02-08 20:34:49 |
+----+---------------------+
1 row in set (0.00 sec)

此时sql进程 从中继日志 读取数据 写入数据库

在mysql外执行

mysqlbinlog  mysqld-relay-bin.000009

[root@bogon mysql]# mysqlbinlog  mysqld-relay-bin.000009
/*!50530 SET @@SESSION.PSEUDO_SLAVE_MODE=1*/;
/*!40019 SET @@session.max_insert_delayed_threads=0*/;
/*!50003 SET @OLD_COMPLETION_TYPE=@@COMPLETION_TYPE,COMPLETION_TYPE=0*/;
DELIMITER /*!*/;
# at 4
#170208 20:39:46 server id 163  end_log_pos 120 CRC32 0xbdb725c4        Start: binlog v 4, server v 5.6.35 created 170208 20:39:46
BINLOG '
khGbWA+jAAAAdAAAAHgAAABAAAQANS42LjM1AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAAAAAAEzgNAAgAEgAEBAQEEgAAXAAEGggAAAAICAgCAAAACgoKGRkAAcQl
t70=
'/*!*/;
# at 120
#170208 20:39:46 server id 108  end_log_pos 0 CRC32 0x0649f72c  Rotate to mysql-bin.000005  pos: 4
# at 167
#170208 20:33:47 server id 108  end_log_pos 120 CRC32 0x045c4ff1        Start: binlog v 4, server v 5.6.35-log created 170208 20:33:47
BINLOG '
KxCbWA9sAAAAdAAAAHgAAAAAAAQANS42LjM1LWxvZwAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAAAAAAEzgNAAgAEgAEBAQEEgAAXAAEGggAAAAICAgCAAAACgoKGRkAAfFP
XAQ=
'/*!*/;
# at 283
#170208 20:34:49 server id 108  end_log_pos 203 CRC32 0xb10230cc        Query   thread_id=9     exec_time=0     error_code=0
SET TIMESTAMP=1486557289/*!*/;
SET @@session.pseudo_thread_id=9/*!*/;
SET @@session.foreign_key_checks=1, @@session.sql_auto_is_null=0, @@session.unique_checks=1, @@session.autocommit=1/*!*/;
SET @@session.sql_mode=1075838976/*!*/;
SET @@session.auto_increment_increment=1, @@session.auto_increment_offset=1/*!*/;
/*!\C utf8 *//*!*/;
SET @@session.character_set_client=33,@@session.collation_connection=33,@@session.collation_server=8/*!*/;
SET @@session.time_zone='SYSTEM'/*!*/;
SET @@session.lc_time_names=0/*!*/;
SET @@session.collation_database=DEFAULT/*!*/;
BEGIN
/*!*/;
# at 366
#170208 20:34:49 server id 108  end_log_pos 313 CRC32 0x59ee4c4e        Query   thread_id=9     exec_time=0     error_code=0
use `hk`/*!*/;
SET TIMESTAMP=1486557289/*!*/;
insert into test values(4,now())
/*!*/;
# at 476
#170208 20:34:49 server id 108  end_log_pos 344 CRC32 0x1735772f        Xid = 110
COMMIT/*!*/;
DELIMITER ;
# End of log file
ROLLBACK /* added by mysqlbinlog */;
/*!50003 SET COMPLETION_TYPE=@OLD_COMPLETION_TYPE*/;
/*!50530 SET @@SESSION.PSEUDO_SLAVE_MODE=0*/;

复制特点
1.sql更新,没写binary log 不可能复制
2.正在执行的sql更新,也不可能被复制
3.只有执行完成而且成功的语句才会被复制