17.2.1.6 向组中添加实例

此时,该组中有一个成员,即服务器 s1,其中有一些数据。现在是时候通过添加之前配置的其他两个服务器来扩展该组了。

17.2.1.6.1 添加第二个实例

为了添加第二个实例,服务器 s2,首先为其创建配置文件。该配置类似于用于服务器 s1 的配置,除了 server_id. 这些不同的行在下面的清单中突出显示。

[mysqld]

#
# Disable other storage engines
#
disabled_storage_engines="MyISAM,BLACKHOLE,FEDERATED,ARCHIVE,MEMORY"

#
# Replication configuration parameters
#
server_id=2
gtid_mode=ON
enforce_gtid_consistency=ON
master_info_repository=TABLE
relay_log_info_repository=TABLE
binlog_checksum=NONE
log_slave_updates=ON
log_bin=binlog
binlog_format=ROW

#
# Group Replication configuration
#
transaction_write_set_extraction=XXHASH64
group_replication_group_name="aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa"
group_replication_start_on_boot=off
group_replication_local_address= "s2:33061"
group_replication_group_seeds= "s1:33061,s2:33061,s3:33061"
group_replication_bootstrap_group= off

与服务器 s1 的过程类似,使用适当的选项文件启动服务器。然后按如下方式配置恢复凭据。这些命令与设置服务器 s1 时使用的命令相同,因为该用户在组内共享。该成员需要在第 17.2.1.3 节,“用户凭证”中配置相同的复制用户。如果您依赖分布式恢复在所有成员上配置用户,则当 s2 连接到种子 s1 时,复制用户将重新关联到 s1。如果在 s1 上配置用户凭证时没有启用二进制日志记录,则必须在 s2 上创建复制用户。在这种情况下,连接到 s2 并发出:

SET SQL_LOG_BIN=0;
CREATE USER rpl_user@'%' IDENTIFIED BY 'password';
GRANT REPLICATION SLAVE ON *.* TO rpl_user@'%';
SET SQL_LOG_BIN=1;
CHANGE MASTER TO MASTER_USER='rpl_user', MASTER_PASSWORD='password' \\
	FOR CHANNEL 'group_replication_recovery';

如有必要,请安装组复制插件,请参阅 第 17.2.1.4 节,“启动组复制”

Start Group Replication 和 s2 开始加入组的过程。

mysql> START GROUP_REPLICATION;

与之前在 s1 上执行的步骤相同的步骤不同,这里的不同之处在于您 不需要boostrap 组,因为该组已经存在。换句话说,在 s2 group_replication_bootstrap_group 上设置为关闭,并且在启动组复制之前不要发出SET GLOBAL group_replication_bootstrap_group=ON;,因为该组已经由服务器 s1 创建并引导。此时只需要将服务器s2添加到已经存在的组中即可。

小费

当组复制成功启动并且服务器加入组时,它会检查 super_read_only变量。通过在成员的配置文件中设置super_read_only 为 ON,您可以确保由于任何原因在启动 Group Replication 时失败的服务器不接受事务。如果服务器应作为读写实例加入组,例如作为单主组中的主实例或作为多主组的成员,当 super_read_only变量设置为 ON 时,则在加入时将其设置为 OFF群组。

再次查看 performance_schema.replication_group_members 表发现组中现在有两个 ONLINE服务器。

mysql> SELECT * FROM performance_schema.replication_group_members;
+---------------------------+--------------------------------------+-------------+-------------+---------------+
| CHANNEL_NAME              | MEMBER_ID                            | MEMBER_HOST | MEMBER_PORT | MEMBER_STATE  |
+---------------------------+--------------------------------------+-------------+-------------+---------------+
| group_replication_applier | 395409e1-6dfa-11e6-970b-00212844f856 |   s1        |        3306 | ONLINE        |
| group_replication_applier | ac39f1e6-6dfa-11e6-a69d-00212844f856 |   s2        |        3306 | ONLINE        |
+---------------------------+--------------------------------------+-------------+-------------+---------------+

当 s2 尝试加入该组时, 第 17.9.5 节“分布式恢复” 确保 s2 应用了与 s1 应用的相同事务。一旦这个过程完成,s2 就可以作为成员加入该组,此时它被标记为 ONLINE。换句话说,它必须已经自动赶上服务器 s1。一旦 s2 在线,它就会开始处理与该组的交易。验证 s2 确实已与服务器 s1 同步,如下所示。

mysql> SHOW DATABASES LIKE 'test';
+-----------------+
| Database (test) |
+-----------------+
| test            |
+-----------------+

mysql> SELECT * FROM test.t1;
+----+------+
| c1 | c2   |
+----+------+
|  1 | Luis |
+----+------+

mysql> SHOW BINLOG EVENTS;
+---------------+------+----------------+-----------+-------------+--------------------------------------------------------------------+
| Log_name      | Pos  | Event_type     | Server_id | End_log_pos | Info                                                               |
+---------------+------+----------------+-----------+-------------+--------------------------------------------------------------------+
| binlog.000001 |    4 | Format_desc    |         2 |         123 | Server ver: 5.7.40-log, Binlog ver: 4                              |
| binlog.000001 |  123 | Previous_gtids |         2 |         150 |                                                                    |
| binlog.000001 |  150 | Gtid           |         1 |         211 | SET @@SESSION.GTID_NEXT= 'aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa:1'  |
| binlog.000001 |  211 | Query          |         1 |         270 | BEGIN                                                              |
| binlog.000001 |  270 | View_change    |         1 |         369 | view_id=14724832985483517:1                                        |
| binlog.000001 |  369 | Query          |         1 |         434 | COMMIT                                                             |
| binlog.000001 |  434 | Gtid           |         1 |         495 | SET @@SESSION.GTID_NEXT= 'aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa:2'  |
| binlog.000001 |  495 | Query          |         1 |         585 | CREATE DATABASE test                                               |
| binlog.000001 |  585 | Gtid           |         1 |         646 | SET @@SESSION.GTID_NEXT= 'aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa:3'  |
| binlog.000001 |  646 | Query          |         1 |         770 | use `test`; CREATE TABLE t1 (c1 INT PRIMARY KEY, c2 TEXT NOT NULL) |
| binlog.000001 |  770 | Gtid           |         1 |         831 | SET @@SESSION.GTID_NEXT= 'aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa:4'  |
| binlog.000001 |  831 | Query          |         1 |         890 | BEGIN                                                              |
| binlog.000001 |  890 | Table_map      |         1 |         933 | table_id: 108 (test.t1)                                            |
| binlog.000001 |  933 | Write_rows     |         1 |         975 | table_id: 108 flags: STMT_END_F                                    |
| binlog.000001 |  975 | Xid            |         1 |        1002 | COMMIT /* xid=30 */                                                |
| binlog.000001 | 1002 | Gtid           |         1 |        1063 | SET @@SESSION.GTID_NEXT= 'aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa:5'  |
| binlog.000001 | 1063 | Query          |         1 |        1122 | BEGIN                                                              |
| binlog.000001 | 1122 | View_change    |         1 |        1261 | view_id=14724832985483517:2                                        |
| binlog.000001 | 1261 | Query          |         1 |        1326 | COMMIT                                                             |
+---------------+------+----------------+-----------+-------------+--------------------------------------------------------------------+

如上所示,第二台服务器已添加到组中,并使用分布式恢复自动从服务器 s1 复制了更改。换句话说,到s2加入组的时间点,在s1上应用的事务已经被复制到s2。

17.2.1.6.2 添加附加实例

向组中添加其他实例基本上与添加第二个服务器的步骤顺序相同,只是必须像服务器 s2 那样更改配置。总结所需的命令:

1.创建配置文件

[mysqld]

#
# Disable other storage engines
#
disabled_storage_engines="MyISAM,BLACKHOLE,FEDERATED,ARCHIVE,MEMORY"

#
# Replication configuration parameters
#
server_id=3
gtid_mode=ON
enforce_gtid_consistency=ON
master_info_repository=TABLE
relay_log_info_repository=TABLE
binlog_checksum=NONE
log_slave_updates=ON
log_bin=binlog
binlog_format=ROW

#
# Group Replication configuration
#
group_replication_group_name="aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa"
group_replication_start_on_boot=off
group_replication_local_address= "s3:33061"
group_replication_group_seeds= "s1:33061,s2:33061,s3:33061"
group_replication_bootstrap_group= off

2. 启动服务器并连接到它。为 group_replication_recovery 通道配置恢复凭据。

SET SQL_LOG_BIN=0;
CREATE USER rpl_user@'%' IDENTIFIED BY 'password';
GRANT REPLICATION SLAVE ON *.* TO rpl_user@'%';
FLUSH PRIVILEGES;
SET SQL_LOG_BIN=1;
CHANGE MASTER TO MASTER_USER='rpl_user', MASTER_PASSWORD='password'  \\
FOR CHANNEL 'group_replication_recovery';

4.安装Group Replication插件并启动。

INSTALL PLUGIN group_replication SONAME 'group_replication.so';
START GROUP_REPLICATION;

此时服务器 s3 已启动并运行,已加入组并赶上组中的其他服务器。再次查阅 performance_schema.replication_group_members 表格确认情况确实如此。

mysql> SELECT * FROM performance_schema.replication_group_members;
+---------------------------+--------------------------------------+-------------+-------------+---------------+
| CHANNEL_NAME              | MEMBER_ID                            | MEMBER_HOST | MEMBER_PORT | MEMBER_STATE  |
+---------------------------+--------------------------------------+-------------+-------------+---------------+
| group_replication_applier | 395409e1-6dfa-11e6-970b-00212844f856 |   s1        |       3306  | ONLINE        |
| group_replication_applier | 7eb217ff-6df3-11e6-966c-00212844f856 |   s3        |       3306  | ONLINE        |
| group_replication_applier | ac39f1e6-6dfa-11e6-a69d-00212844f856 |   s2        |       3306  | ONLINE        |
+---------------------------+--------------------------------------+-------------+-------------+---------------+

在服务器 s2 或服务器 s1 上发出相同的查询会产生相同的结果。此外,您可以验证服务器 s3 是否已赶上:

mysql> SHOW DATABASES LIKE 'test';
+-----------------+
| Database (test) |
+-----------------+
| test            |
+-----------------+

mysql> SELECT * FROM test.t1;
+----+------+
| c1 | c2   |
+----+------+
|  1 | Luis |
+----+------+

mysql> SHOW BINLOG EVENTS;
+---------------+------+----------------+-----------+-------------+--------------------------------------------------------------------+
| Log_name      | Pos  | Event_type     | Server_id | End_log_pos | Info                                                               |
+---------------+------+----------------+-----------+-------------+--------------------------------------------------------------------+
| binlog.000001 |    4 | Format_desc    |         3 |         123 | Server ver: 5.7.40-log, Binlog ver: 4                              |
| binlog.000001 |  123 | Previous_gtids |         3 |         150 |                                                                    |
| binlog.000001 |  150 | Gtid           |         1 |         211 | SET @@SESSION.GTID_NEXT= 'aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa:1'  |
| binlog.000001 |  211 | Query          |         1 |         270 | BEGIN                                                              |
| binlog.000001 |  270 | View_change    |         1 |         369 | view_id=14724832985483517:1                                        |
| binlog.000001 |  369 | Query          |         1 |         434 | COMMIT                                                             |
| binlog.000001 |  434 | Gtid           |         1 |         495 | SET @@SESSION.GTID_NEXT= 'aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa:2'  |
| binlog.000001 |  495 | Query          |         1 |         585 | CREATE DATABASE test                                               |
| binlog.000001 |  585 | Gtid           |         1 |         646 | SET @@SESSION.GTID_NEXT= 'aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa:3'  |
| binlog.000001 |  646 | Query          |         1 |         770 | use `test`; CREATE TABLE t1 (c1 INT PRIMARY KEY, c2 TEXT NOT NULL) |
| binlog.000001 |  770 | Gtid           |         1 |         831 | SET @@SESSION.GTID_NEXT= 'aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa:4'  |
| binlog.000001 |  831 | Query          |         1 |         890 | BEGIN                                                              |
| binlog.000001 |  890 | Table_map      |         1 |         933 | table_id: 108 (test.t1)                                            |
| binlog.000001 |  933 | Write_rows     |         1 |         975 | table_id: 108 flags: STMT_END_F                                    |
| binlog.000001 |  975 | Xid            |         1 |        1002 | COMMIT /* xid=29 */                                                |
| binlog.000001 | 1002 | Gtid           |         1 |        1063 | SET @@SESSION.GTID_NEXT= 'aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa:5'  |
| binlog.000001 | 1063 | Query          |         1 |        1122 | BEGIN                                                              |
| binlog.000001 | 1122 | View_change    |         1 |        1261 | view_id=14724832985483517:2                                        |
| binlog.000001 | 1261 | Query          |         1 |        1326 | COMMIT                                                             |
| binlog.000001 | 1326 | Gtid           |         1 |        1387 | SET @@SESSION.GTID_NEXT= 'aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa:6'  |
| binlog.000001 | 1387 | Query          |         1 |        1446 | BEGIN                                                              |
| binlog.000001 | 1446 | View_change    |         1 |        1585 | view_id=14724832985483517:3                                        |
| binlog.000001 | 1585 | Query          |         1 |        1650 | COMMIT                                                             |
+---------------+------+----------------+-----------+-------------+--------------------------------------------------------------------+