MySQL半同步安裝以及參數

基于MySQL5.5

官檔地址：

Semisynchronous Replication Administrative Interface
https://dev.mysql.com/doc/refman/5.5/en/replication-semisync-interface.html

控制半同步復制的系統參數

rpl_semi_sync_master_enabled
Controls whether semisynchronous replication is enabled on the master. To enable or disable the plugin, set this variable to 1 or 0, respectively. The default is 0 (off).
控制是否啟用半同步復制rpl_semi_sync_master_timeout
A value in milliseconds that controls how long the master waits on a commit for acknowledgment from a slave before timing out and reverting to asynchronous replication. The default value is 10000 (10 seconds).
等待從庫提交并反饋的超時時間，超時則轉向異步同步rpl_semi_sync_slave_enabled
Similar to rpl_semi_sync_master_enabled, but controls the slave plugin. 
類似于 rpl_semi_sync_master_enabled，但是用于控制 slave 的插件。

啟用半同步復制監視的狀態變量

Rpl_semi_sync_master_clients
The number of semisynchronous slaves.
半同步復制的 slave 的數量Rpl_semi_sync_master_status
Whether semisynchronous replication currently is operational on the master. The value is 1 if the plugin has been enabled and a commit acknowledgment has occurred. It is 0 if the plugin is not enabled or the master has fallen back to asynchronous replication due to commit acknowledgment timeout.
半同步復制目前是否運行在主機上。如果已啟用該插件，提交確認發生，值為 1。如果未啟用該插件或 master 已經回落到異步復制導致提交確認超時，為 0。Rpl_semi_sync_master_no_tx
The number of commits that were not acknowledged successfully by a slave.
提交但是沒有反饋成功的slave的數量。Rpl_semi_sync_master_yes_tx
The number of commits that were acknowledged successfully by a slave.
提交后反饋成功的slave的數量。Rpl_semi_sync_slave_status
Whether semisynchronous replication currently is operational on the slave. This is 1 if the plugin has been enabled and the slave I/O thread is running, 0 otherwise.
是否同步復制目前是業務上的slave。如果已啟用該插件，slave的 I/O 線程正在運行，是1 ，否則 0。

安裝和配置

前提條件

1. MySQL 5.5 or higher must be installed.
2. The capability of installing plugins requires a MySQL server that supports dynamic loading. To verify this, check that the value of the have_dynamic_loading system variable is YES. Binary distributions should support dynamic loading.
3. Replication must already be working. 

安裝

1.設置主從庫參數文件
[mysqld]
plugin_dir=/path/to/plugin/directory
主庫：
INSTALL PLUGIN rpl_semi_sync_master SONAME 'semisync_master.so';
從庫:
INSTALL PLUGIN rpl_semi_sync_slave SONAME 'semisync_slave.so';
查詢安裝情況
mysql> SELECT PLUGIN_NAME, PLUGIN_STATUS FROM INFORMATION_SCHEMA.PLUGINS WHERE PLUGIN_NAME LIKE '%semi%';
+----------------------+---------------+
| PLUGIN_NAME          | PLUGIN_STATUS |
+----------------------+---------------+
| rpl_semi_sync_master | ACTIVE        |
+----------------------+---------------+
安裝完成后，半同步默認是關閉的，需要在主從庫上面都開啟，才能使用，只開啟主或者從，都無法使用mysql運行時，可以使用以下參數
主庫：
SET GLOBAL rpl_semi_sync_master_enabled = {0|1};    #默認是0，1是啟用，0是關閉
SET GLOBAL rpl_semi_sync_master_timeout = N;        #單位milliseconds（毫秒），10000毫秒=10秒
從庫： 
SET GLOBAL rpl_semi_sync_slave_enabled = {0|1};
如果要在mysql運行時啟用半同步，必須重啟IO_THREAD，slave會重新連上master并且被注冊為 semisynchronous slave
STOP SLAVE IO_THREAD;
START SLAVE IO_THREAD;
如果不重啟的話，slave將會繼續使用 異步復制可以重啟mysql時
配置my.cof參數
主庫：
[mysqld]
rpl_semi_sync_master_enabled=1
rpl_semi_sync_master_timeout=1000 # 1 second
從庫：
[mysqld]
rpl_semi_sync_slave_enabled=1

監控

mysql> SHOW VARIABLES LIKE 'rpl_semi_sync%';
mysql> SHOW STATUS LIKE 'Rpl_semi_sync%';

卸載

主庫：
UNINSTALL PLUGIN rpl_semi_sync_master;
從庫:
UNINSTALL PLUGIN rpl_semi_sync_slave;

轉載于:https://www.cnblogs.com/Coye/p/7256068.html

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