组复制的作用： The following examples are typical use cases for Group Replication. Elastic Replication-
组复制的作用：
The following examples are typical use cases for Group Replication.
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Elastic Replication - Environments that require a very fluid replication infrastructure, where the number of servers has to grow or shrink dynamically and with as few side-effects as possible. For instance, database services for the cloud.
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Highly Available Shards - Sharding is a popular approach to achieve write scale-out. Use MySQL Group Replication to implement highly available shards, where each shard maps to a replication group.
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Alternative to Master-Slave replication - In certain situations, using a single master server makes it a single point of contention. Writing to an entire group may prove more scalable under certain circumstances.
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Autonomic Systems - Additionally, you can deploy MySQL Group Replication purely for the automation that is built into the replication protocol (described already in this and previous chapters).
官网给出的示意图
之前应
1.修改主机名与映射
参考：https://my.oschina.net/u/3407012/blog/889505
2.防火墙
参考：https://my.oschina.net/u/3407012/blog/889528
第一步：安装MySql 5.7，参考 https://my.oschina.net/u/3407012/blog/889497
第二步：修改 MySql 配置文件，增加以下配置
# *********** configure replication according *******************************user=mysqlserver_id=154（标识每个机器，一般取ip最后段）gtid_mode=ONenforce_gtid_consistency=ONmaster_info_repository=TABLErelay_log_info_repository=TABLEbinlog_checksum=NONElog_slave_updates=ONlog_bin=binlogbinlog_format=ROW# *********** Group Replication Settings *************************************transaction_write_set_extraction=XXHASH64loose-group_replication_group_name="aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa"loose-group_replication_start_on_boot=offloose-group_replication_local_address= "host4:24904"loose-group_replication_group_seeds= "host1:24901,host3:24903,host4:24904"loose-group_replication_bootstrap_group= off第三步：创建凭证
可参考https://dev.mysql.com/doc/refman/5.7/en/group-replication-user-credentials.html
mysql> SET SQL_LOG_BIN=0;Query OK, 0 rows affected (0,00 sec)mysql> CREATE USER rpl_user@'%';Query OK, 0 rows affected (0,00 sec)mysql> GRANT REPLICATION SLAVE ON *.* TO rpl_user@'%' IDENTIFIED BY 'rpl_pass';Query OK, 0 rows affected, 1 warning (0,00 sec)mysql> FLUSH PRIVILEGES;Query OK, 0 rows affected (0,00 sec)mysql> SET SQL_LOG_BIN=1;Query OK, 0 rows affected (0,00 sec)
mysql> CHANGE MASTER TO MASTER_USER='rpl_user', MASTER_PASSWORD='rpl_pass' FOR CHANNEL 'group_replication_recovery';Query OK, 0 rows affected, 2 warnings (0,01 sec)第四步：安装组复制插件
mysql>INSTALL PLUGIN group_replication SONAME 'group_replication.so'; mysql> SHOW PLUGINS;+----------------------------+----------+--------------------+----------------------+-------------+| Name | Status | Type | Library | License |+----------------------------+----------+--------------------+----------------------+-------------+| binlog | ACTIVE | STORAGE ENGINE | NULL | PROPRIETARY |(...)| group_replication | ACTIVE | GROUP REPLICATION | group_replication.so | PROPRIETARY |+----------------------------+----------+--------------------+----------------------+------------
第五步：开启组
SET GLOBAL group_replication_bootstrap_group=ON;START GROUP_REPLICATION;SET GLOBAL group_replication_bootstrap_group=OFF;
mysql> SELECT * FROM performance_schema.replication_group_members;+---------------------------+--------------------------------------+-------------+-------------+--------------+| CHANNEL_NAME | MEMBER_ID | MEMBER_HOST | MEMBER_PORT | MEMBER_STATE |+---------------------------+--------------------------------------+-------------+-------------+--------------+| group_replication_applier | 17d5e429-2cc0-11e7-b506-00505684822e | host3 | 33063 | ONLINE |+---------------------------+--------------------------------------+-------------+-------------+--------------+
第六步：新增SLAVE
同上第五步之前，第五步时需要
mysql> set global group_replication_allow_local_disjoint_gtids_join=ON;mysql> START GROUP_REPLICATION;Query OK, 0 rows affected (44,88 sec)mysql> SELECT * FROM performance_schema.replication_group_members;+---------------------------+--------------------------------------+-------------+-------------+--------------+| CHANNEL_NAME | MEMBER_ID | MEMBER_HOST | MEMBER_PORT | MEMBER_STATE |+---------------------------+--------------------------------------+-------------+-------------+--------------+| group_replication_applier | 17d5e429-2cc0-11e7-b506-00505684822e | host3 | 33063 | ONLINE || group_replication_applier | 59fae48b-2cc4-11e7-bba9-005056844614 | host1 | 33061 | ONLINE || group_replication_applier | f3c27092-2ce0-11e7-9729-00505684d3b9 | host4 | 33064 | ONLINE |+---------------------------+--------------------------------------+-------------+-------------+--------------+3 rows in set (0.00 sec)
第八步：创建测试数据
mysql> CREATE DATABASE test;Query OK, 1 row affected (0,00 sec)mysql> use testDatabase changedmysql> CREATE TABLE t1 (c1 INT PRIMARY KEY, c2 TEXT NOT NULL);Query OK, 0 rows affected (0,00 sec)mysql> INSERT INTO t1 VALUES (1, 'Luis');Query OK, 1 row affected (0,01 sec)
mysql> SELECT * FROM t1;+----+------+| c1 | c2 |+----+------+| 1 | Luis |+----+------+1 row in set (0,00 sec)mysql> SHOW BINLOG EVENTS;+---------------+-----+----------------+-----------+-------------+--------------------------------------------------------------------+| Log_name | Pos | Event_type | Server_id | End_log_pos | Info |+---------------+-----+----------------+-----------+-------------+--------------------------------------------------------------------+| binlog.000001 | 4 | Format_desc | 1 | 123 | Server ver: 5.7.17-gr080-log, Binlog ver: 4 || binlog.000001 | 123 | Previous_gtids | 1 | 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=14724817264259180:1 || 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 | 899 | BEGIN || binlog.000001 | 899 | Table_map | 1 | 942 | table_id: 108 (test.t1) || binlog.000001 | 942 | Write_rows | 1 | 984 | table_id: 108 flags: STMT_END_F || binlog.000001 | 984 | Xid | 1 | 1011 | COMMIT /* xid=38 */ |+---------------+-----+----------------+-----------+-------------+--------------------------------------------------------------------+15 rows in set (0,00 sec)
第九步：查看其他节点是否有数据
如要想动态扩容，那么需要在其他节点上执行：
mysql> set global group_replication_group_seeds="host1:24901,host2:24902...";Query OK, 0 rows affected (0.00 sec)mysql> show variables like '%group_replication_group_seeds%';+-------------------------------+-----------------------------------------------------+| Variable_name | Value |+-------------------------------+-----------------------------------------------------+| group_replication_group_seeds | host1:24901,host2:24902 ... |+-------------------------------+-----------------------------------------------------+1 row in set (0.00 sec)其他命令
1.查询谁是主(Single-Primary Mode)：
SELECT VARIABLE_VALUE FROM performance_schema.global_status WHERE VARIABLE_NAME= 'group_replication_primary_member';
