MySQL semi-synchronous replication Mode

Mysql replication is completed asynchronously by default. The semi-Sync Mode is a patch developed by google for mysql. This function has been integrated in Mysql 5.5 or later versions. Semi-sync means that the MASTER only needs to receive the returned information of one of the SLAVE, and then commit; otherwise, wait until the timeout time is reached and switch to asynchronous mode before committing. This operation reduces the latency of data in the Master/Slave database, and improves data security with minimal performance loss.

Enabling semi-sync is simple. You need to install and enable the semi-sync plug-in on both the master and slave.

Check whether semi-sync is used for mysql replication,

Mysql> show variables like 'rpl % ';

+ ----------------- + ------- +

| Variable_name | Value |

+ ----------------- + ------- +

| Rpl_recovery_rank | 0 |

+ ----------------- + ------- +

1 row in set (0.00 sec)

Or use show status like 'rpl % ';

Enable semi-Sync Mode:

Run on master

Mysql> install plugin rpl_semi_sync_master soname 'semisync _ master. so ';

Query OK, 0 rows affected (0.03 sec)

Mysql> set global rpl_semi_sync_master_enabled = 0;

Query OK, 0 rows affected (0.00 sec)

 

Mysql> show variables like 'rpl % ';

+ ------------------------------------ + ------- +

| Variable_name | Value |

+ ------------------------------------ + ------- +

| Rpl_recovery_rank | 0 |

| Rpl_semi_sync_master_enabled | OFF |

| Rpl_semi_sync_master_timeout | 10000 |

| Rpl_semi_sync_master_trace_level | 32 |

| Rpl_semi_sync_master_wait_no_slave | ON |

+ ------------------------------------ + ------- +

5 rows in set (0.00 sec)

 

Mysql> set global rpl_semi_sync_master_enabled = 1;

Query OK, 0 rows affected (0.00 sec)

 

Mysql> show variables like 'rpl % ';

+ ------------------------------------ + ------- +

| Variable_name | Value |

+ ------------------------------------ + ------- +

| Rpl_recovery_rank | 0 |

| Rpl_semi_sync_master_enabled | ON |

| Rpl_semi_sync_master_timeout | 10000 |

| Rpl_semi_sync_master_trace_level | 32 |

| Rpl_semi_sync_master_wait_no_slave | ON |

+ ------------------------------------ + ------- +

The value of rpl_semi_sync_master_enabled is 0 (on) or 1 (off). The default value is 1.

The default value of rpl_semi_sync_master_timeout is 10000 (10 s)

5 rows in set (0.00 sec)

Perform the following operations on slave:

Mysql> install plugin rpl_semi_sync_slave soname 'semisync _ slave. so ';

Query OK, 0 rows affected (0.03 sec)

 

Mysql> set global rpl_semi_sync_slave_enabled = 1;

Query OK, 0 rows affected (0.00 sec)

 

Mysql> show variables like 'rpl % ';

+ --------------------------------- + ------- +

| Variable_name | Value |

+ --------------------------------- + ------- +

| Rpl_recovery_rank | 0 |

| Rpl_semi_sync_slave_enabled | ON |

| Rpl_semi_sync_slave_trace_level | 32 |

+ --------------------------------- + ------- +

3 rows in set (0.00 sec)

 

Mysql> show status like 'rpl % ';

+ ---------------------------- + ------------- +

| Variable_name | Value |

+ ---------------------------- + ------------- +

| Rpl_semi_sync_slave_status | ON |

| Rpl_status | AUTH_MASTER |

+ ---------------------------- + ------------- +

2 rows in set (0.01 sec)

Mysql> stop slave io_thread;

Query OK, 0 rows affected (0.00 sec)

 

Mysql> start slave io_thread;

Query OK, 0 rows affected (0.00 sec)

 

The value of rpl_semi_sync_slave_enabled is 0 (on) or 1 (off). The default value is 1.

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