ProxySQL官檔翻譯__04_ProxySQL配置之MySQL服務器配置

04_ProxySQL配置之MySQL服務器配置

備註：文章編寫時間201904-201905期間，後續官方在github的更新沒有被寫入

MySQL服務器配置 [MySQL Server Configuration]

一、在ProxySQL中配置後端MySQL服務器[Configuring Backend MySQL Servers in ProxySQL]

MySQL服務器的配置在mysql_servers表和mysql_replication_hostgroups表（可選）中。

友情提醒：在閱讀下部分之前，請確保瞭解了ProxySQL使用的多層配置系統。

特別注意:
1）如果沒有運行LOAD MYSQL SERVERS TO RUNTIME，那麼mysql_servers和mysql_replication_hostgroups表中的更改不會生效；
2）如果沒有運行SAVE MYSQL SERVERS TO DISK 保存配置到的磁盤，那麼mysql_servers和mysql_replication_hostgroups表中的更改
將在重啓/崩潰後丟失。

對mysql_servers和mysql_replication_hostgroups的更改將被視爲編輯配置文件而不會被保存或讓服務重新加載。

二、將mysql服務器配置從MEMORY層複製到RUNTIME層 [Copying mysql servers from memory to runtime]

將MySQL服務器和複製主機組配置信息從MEMORY層數據庫加載到RUNTIME層的數據結構在中：

Admin> LOAD MYSQL SERVERS TO RUNTIME;

其他可被接受的別名操作：
Admin> LOAD MYSQL SERVERS TO RUN;

Admin> LOAD MYSQL SERVERS FROM MEM;

Admin> LOAD MYSQL SERVERS FROM MEMORY;

三、將mysql服務器配置從MEMORY層持久化到DISK層[Copying mysql servers from memory to disk]

將MySQL服務器和複製主機組配置信息從MEMORY層數據庫保留到DISK的數據庫上：

Admin> SAVE MYSQL SERVERS TO DISK;

其他可被接受的別名操作：
Admin> SAVE MYSQL SERVERS FROM MEM;

Admin> SAVE MYSQL SERVERS FROM MEMORY;

四、將mysql服務器配置從RUNTIME層拷貝到MEMORY層[Copying mysql servers from runtime to memory]

將MySQL服務器和複製主機組配置信息從RUNTIME層數據結構保留到MEMORY數據庫：

Admin> SAVE MYSQL SERVERS TO MEMORY;

其他可被接受的別名操作：
Admin> SAVE MYSQL SERVERS TO MEM;

Admin> SAVE MYSQL SERVERS FROM RUN;

Admin> SAVE MYSQL SERVERS FROM RUNTIME;

五、將mysql服務器從DISK層複製到MEMORY層[Copying mysql servers from disk to memory]

將MySQL服務器和複製主機組配置信息從DISK層數據庫加載到MEMORY層數據庫：

Admin> LOAD MYSQL SERVERS TO MEMORY;

其他可被接受的別名操作：
Admin> LOAD MYSQL SERVERS TO MEM;

Admin> LOAD MYSQL SERVERS FROM DISK;

六、新增服務器[Adding a new server]

如果要添加新服務器，必須在mysql_servers表中插入新行以記錄相關配置信息。注意，該表有幾列是有默認值的。
以下添加了一個具有所有默認配置的新後端(服務器)：

Admin> SELECT * FROM mysql_servers;
Empty set (0.00 sec)

Admin> INSERT INTO mysql_servers (hostname) VALUES ('127.0.0.1');
Query OK, 1 row affected (0.00 sec)

Admin> SELECT * FROM mysql_servers\G
*************************** 1. row ***************************
       hostgroup_id: 0
           hostname: 127.0.0.1
               port: 3306
          gtid_port: 0
             status: ONLINE
             weight: 1
        compression: 0
    max_connections: 1000
max_replication_lag: 0
            use_ssl: 0
     max_latency_ms: 0
            comment: 
1 row in set (0.00 sec)

七、將新服務器添加到主機組[Adding new servers to a hostgroup]

Admin> SELECT hostgroup_id,hostname,port FROM mysql_servers;
+--------------+-----------+------+
| hostgroup_id | hostname  | port |
+--------------+-----------+------+
| 0            | 127.0.0.1 | 3306 |
+--------------+-----------+------+
1 row in set (0.00 sec)

INSERT INTO mysql_servers (hostgroup_id, hostname ,port) 
VALUES (1, '127.0.0.1' ,24801), (1, '127.0.0.1' ,24802), (1,'127.0.0.1' ,24803);
Query OK, 3 rows affected (0.00 sec)

Admin> SELECT hostgroup_id,hostname,port FROM mysql_servers;
+--------------+-----------+-------+
| hostgroup_id | hostname  | port  |
+--------------+-----------+-------+
| 0            | 127.0.0.1 | 3306  |
| 1            | 127.0.0.1 | 24801 |
| 1            | 127.0.0.1 | 24802 |
| 1            | 127.0.0.1 | 24803 |
+--------------+-----------+-------+
4 rows in set (0.00 sec)

八、配置與後端的連接數限制[Limiting the number of connections to a backend]

Admin> SELECT hostgroup_id,hostname,port,max_connections FROM mysql_servers;
+--------------+-----------+-------+-----------------+
| hostgroup_id | hostname  | port  | max_connections |
+--------------+-----------+-------+-----------------+
| 0            | 127.0.0.1 | 3306  | 1000            |
| 1            | 127.0.0.1 | 24801 | 1000            |
| 1            | 127.0.0.1 | 24802 | 1000            |
| 1            | 127.0.0.1 | 24803 | 1000            |
+--------------+-----------+-------+-----------------+
4 rows in set (0.00 sec)

Admin> UPDATE mysql_servers SET max_connections=10 WHERE hostname='127.0.0.1' AND port=24802;
Query OK, 1 row affected (0.00 sec)

Admin> SELECT hostgroup_id,hostname,port,max_connections FROM mysql_servers;
+--------------+-----------+-------+-----------------+
| hostgroup_id | hostname  | port  | max_connections |
+--------------+-----------+-------+-----------------+
| 0            | 127.0.0.1 | 3306  | 1000            |
| 1            | 127.0.0.1 | 24801 | 1000            |
| 1            | 127.0.0.1 | 24802 | 10              |
| 1            | 127.0.0.1 | 24803 | 1000            |
+--------------+-----------+-------+-----------------+
4 rows in set (0.00 sec)

九、通過改變後端的權重來確定流量的優先級[Prioritizing traffic by changing the weight of a backend]

特別注意：權重僅在主機組內起作用，值越大被分到的流量的機率越多！！

Admin> SELECT hostgroup_id,hostname,port,weight FROM mysql_servers;
+--------------+-----------+-------+--------+
| hostgroup_id | hostname  | port  | weight |
+--------------+-----------+-------+--------+
| 0            | 127.0.0.1 | 3306  | 1      |
| 1            | 127.0.0.1 | 24801 | 1      |
| 1            | 127.0.0.1 | 24802 | 1      |
| 1            | 127.0.0.1 | 24803 | 1      |
+--------------+-----------+-------+--------+
4 rows in set (0.00 sec)

Admin> UPDATE mysql_servers SET weight=1000 WHERE port IN (24803) AND hostgroup_id=1;
Query OK, 1 row affected (0.00 sec)

Admin> SELECT hostgroup_id,hostname,port,weight FROM mysql_servers;
+--------------+-----------+-------+--------+
| hostgroup_id | hostname  | port  | weight |
+--------------+-----------+-------+--------+
| 0            | 127.0.0.1 | 3306  | 1      |
| 1            | 127.0.0.1 | 24801 | 1      |
| 1            | 127.0.0.1 | 24802 | 1      |
| 1            | 127.0.0.1 | 24803 | 1000   |
+--------------+-----------+-------+--------+
4 rows in set (0.00 sec)

十、對特定後端使用SSL連接[Using SSL connections for a specific backend]

此示例顯示如何爲後端配置SSL(一個狀態值而已),(但這不是全局配置SSL，全局請移步SSL configuration)。

Admin> SELECT hostgroup_id,hostname,port,use_ssl FROM mysql_servers;
+--------------+-----------+-------+---------+
| hostgroup_id | hostname  | port  | use_ssl |
+--------------+-----------+-------+---------+
| 0            | 127.0.0.1 | 3306  | 0       |
| 1            | 127.0.0.1 | 24801 | 0       |
| 1            | 127.0.0.1 | 24802 | 0       |
| 1            | 127.0.0.1 | 24803 | 0       |
+--------------+-----------+-------+---------+
4 rows in set (0.00 sec)

Admin> UPDATE mysql_servers SET use_ssl=1 WHERE hostname='127.0.0.1' AND port=3306;
Query OK, 1 row affected (0.00 sec)

Admin> SELECT hostgroup_id,hostname,port,use_ssl FROM mysql_servers;
+--------------+-----------+-------+---------+
| hostgroup_id | hostname  | port  | use_ssl |
+--------------+-----------+-------+---------+
| 0            | 127.0.0.1 | 3306  | 1       |
| 1            | 127.0.0.1 | 24801 | 0       |
| 1            | 127.0.0.1 | 24802 | 0       |
| 1            | 127.0.0.1 | 24803 | 0       |
+--------------+-----------+-------+---------+
4 rows in set (0.00 sec)

十一、配置自動忽略(有複製延時的SLAVE)的延時閥值 [Automatically shunning slaves with replication lag]

Admin> SELECT hostgroup_id,hostname,port,max_replication_lag FROM mysql_servers;
+--------------+-----------+-------+---------------------+
| hostgroup_id | hostname  | port  | max_replication_lag |
+--------------+-----------+-------+---------------------+
| 0            | 127.0.0.1 | 3306  | 0                   |
| 1            | 127.0.0.1 | 24801 | 0                   |
| 1            | 127.0.0.1 | 24802 | 0                   |
| 1            | 127.0.0.1 | 24803 | 0                   |
+--------------+-----------+-------+---------------------+
4 rows in set (0.00 sec)

Admin> UPDATE mysql_servers SET max_replication_lag=30 WHERE hostname='127.0.0.1' AND port=24803;
Query OK, 1 row affected (0.00 sec)

Admin> SELECT hostgroup_id,hostname,port,max_replication_lag FROM mysql_servers;
+--------------+-----------+-------+---------------------+
| hostgroup_id | hostname  | port  | max_replication_lag |
+--------------+-----------+-------+---------------------+
| 0            | 127.0.0.1 | 3306  | 0                   |
| 1            | 127.0.0.1 | 24801 | 0                   |
| 1            | 127.0.0.1 | 24802 | 0                   |
| 1            | 127.0.0.1 | 24803 | 30                  |
+--------------+-----------+-------+---------------------+
4 rows in set (0.00 sec)

使用此配置後，只有在主從複製延遲超過30秒的情況下，SLAVE纔會被自動的暫時忽略。
如果max_replication_lag列設置爲零(SET max_replication_lag = 0)，則Monitor模塊根本不會檢查複製延遲，
即使複製延遲超過了閾值。更多信息請參閱參數mysql-monitor_slave_lag_when_null。

十二、將同一個服務器添加到兩個不同的主機組[Adding a server to two different hostgroups]

mysql_servers表上的主鍵爲(hostgroup_id,hostname,port);這意味着同一服務器可以存在於兩個不同的主機組中。

Admin> SELECT hostgroup_id,hostname,port,weight,max_replication_lag FROM mysql_servers;
+--------------+-----------+-------+--------+---------------------+
| hostgroup_id | hostname  | port  | weight | max_replication_lag |
+--------------+-----------+-------+--------+---------------------+
| 0            | 127.0.0.1 | 3306  | 1      | 0                   |
| 1            | 127.0.0.1 | 24801 | 1      | 0                   |
| 1            | 127.0.0.1 | 24802 | 1      | 0                   |
| 1            | 127.0.0.1 | 24803 | 1000   | 30                  |
+--------------+-----------+-------+--------+---------------------+
4 rows in set (0.00 sec)

Admin> INSERT INTO mysql_servers(hostgroup_id,hostname,port) VALUES (1,'127.0.0.1',3306);
Query OK, 1 row affected (0.00 sec)

Admin> SELECT hostgroup_id,hostname,port,weight,max_replication_lag FROM mysql_servers;
+--------------+-----------+-------+--------+---------------------+
| hostgroup_id | hostname  | port  | weight | max_replication_lag |
+--------------+-----------+-------+--------+---------------------+
| 0            | 127.0.0.1 | 3306  | 1      | 0                   |
| 1            | 127.0.0.1 | 24801 | 1      | 0                   |
| 1            | 127.0.0.1 | 24802 | 1      | 0                   |
| 1            | 127.0.0.1 | 24803 | 1000   | 30                  |
| 1            | 127.0.0.1 | 3306  | 1      | 0                   |
+--------------+-----------+-------+--------+---------------------+
5 rows in set (0.00 sec)

Admin> UPDATE mysql_servers SET max_replication_lag=30, weight=1000;
Query OK, 5 rows affected (0.00 sec)

Admin> UPDATE mysql_servers SET weight=1 WHERE hostname='127.0.0.1' AND hostgroup_id=1 AND port=3306;
Query OK, 1 row affected (0.00 sec)

Admin> SELECT hostgroup_id,hostname,port,weight,max_replication_lag FROM mysql_servers;
+--------------+-----------+-------+--------+---------------------+
| hostgroup_id | hostname  | port  | weight | max_replication_lag |
+--------------+-----------+-------+--------+---------------------+
| 0            | 127.0.0.1 | 3306  | 1000   | 30                  |
| 1            | 127.0.0.1 | 24801 | 1000   | 30                  |
| 1            | 127.0.0.1 | 24802 | 1000   | 30                  |
| 1            | 127.0.0.1 | 24803 | 1000   | 30                  |
| 1            | 127.0.0.1 | 3306  | 1      | 30                  |
+--------------+-----------+-------+--------+---------------------+
5 rows in set (0.00 sec)

在上面的示例中，對於hostgroup爲1的組來說，如果配置爲提供讀取流量，則99.95％的流量將發送到權重爲1000的24801、24802和24803
這3臺服務器上，而0.05％的流量將正常發送到3306上。如果24801、24802和24803這3臺服務器都不可用，那麼所有的讀取流量都將
發往3306上。
注意：max_replication_lag僅適用於SLAVE節點。如果服務器未啓用複製功能，則Monitor不會執行任何操作。

十三、在後端服務器上啓用壓縮[Enable compression on a backend server]

要啓用壓縮，只需將mysql_servers.compression列設置爲非零值就足夠了。
請注意：
1、壓縮功能僅在將該設置加載到RUNTIME層後新建立的連接上生效，之前已有連接不生效。
2、這裏的壓縮是指ProxySQL作爲Client與後端MySQL進行通信時，使用的對數據進行壓縮的功能，類似MySQL客戶端的--compress選項。
MySQL 壓縮協議適合的場景是 MySQL 的服務器端和客戶端之間傳輸的數據量很大，或者可用帶寬不高的情況，典型的場景有如下兩個 :
1> 查詢大量的數據，帶寬不夠(比如導出數據的時候)
2> 複製的時候 binlog 量太大，啓用 slave_compressed_protocol 參數進行日誌壓縮複製。

Admin> SELECT hostgroup_id,hostname,port,compression FROM mysql_servers;
+--------------+-----------+-------+-------------+
| hostgroup_id | hostname  | port  | compression |
+--------------+-----------+-------+-------------+
| 0            | 127.0.0.1 | 3306  | 0           |
| 1            | 127.0.0.1 | 24801 | 0           |
| 1            | 127.0.0.1 | 24802 | 0           |
| 1            | 127.0.0.1 | 24803 | 0           |
| 1            | 127.0.0.1 | 3306  | 0           |
+--------------+-----------+-------+-------------+
5 rows in set (0.00 sec)

Admin> UPDATE mysql_servers SET compression=1 WHERE hostname='127.0.0.1' AND port=24802 AND hostgroup_id=1;
Query OK, 1 row affected (0.00 sec)

Admin> SELECT hostgroup_id,hostname,port,compression FROM mysql_servers;
+--------------+-----------+-------+-------------+
| hostgroup_id | hostname  | port  | compression |
+--------------+-----------+-------+-------------+
| 0            | 127.0.0.1 | 3306  | 0           |
| 1            | 127.0.0.1 | 24801 | 0           |
| 1            | 127.0.0.1 | 24802 | 1           |
| 1            | 127.0.0.1 | 24803 | 0           |
| 1            | 127.0.0.1 | 3306  | 0           |
+--------------+-----------+-------+-------------+
5 rows in set (0.00 sec)

十四、安全的禁用後端服務器[Gracefully disabling a backend server]

要安全的禁用後端服務器，需要將其狀態更改爲 OFFLINE_SOFT 即可。其上活動事務和連接仍將可用，但此後不會向該節點發送新流量。

Admin> SELECT hostgroup_id,hostname,port,status FROM mysql_servers;
+--------------+-----------+-------+--------+
| hostgroup_id | hostname  | port  | status |
+--------------+-----------+-------+--------+
| 0            | 127.0.0.1 | 3306  | ONLINE |
| 1            | 127.0.0.1 | 24801 | ONLINE |
| 1            | 127.0.0.1 | 24802 | ONLINE |
| 1            | 127.0.0.1 | 24803 | ONLINE |
| 1            | 127.0.0.1 | 3306  | ONLINE |
+--------------+-----------+-------+--------+
5 rows in set (0.00 sec)

Admin> UPDATE mysql_servers SET status='OFFLINE_SOFT' WHERE hostname='127.0.0.1' AND port=24802 AND hostgroup_id=1;
Query OK, 1 row affected (0.00 sec)

Admin> SELECT hostgroup_id,hostname,port,status FROM mysql_servers;
+--------------+-----------+-------+--------------+
| hostgroup_id | hostname  | port  | status       |
+--------------+-----------+-------+--------------+
| 0            | 127.0.0.1 | 3306  | ONLINE       |
| 1            | 127.0.0.1 | 24801 | ONLINE       |
| 1            | 127.0.0.1 | 24802 | OFFLINE_SOFT |
| 1            | 127.0.0.1 | 24803 | ONLINE       |
| 1            | 127.0.0.1 | 3306  | ONLINE       |
+--------------+-----------+-------+--------------+
5 rows in set (0.00 sec)

十五、即刻禁用後端服務器[Immediately disabling a backend server]

要立即禁用後端服務器，需要將其狀態更改爲 OFFLINE_HARD 即可。此後，所有當前流量將立即終止，並且不會發送新流量到該節點。

Admin> SELECT hostgroup_id,hostname,port,status FROM mysql_servers;
+--------------+-----------+-------+--------------+
| hostgroup_id | hostname  | port  | status       |
+--------------+-----------+-------+--------------+
| 0            | 127.0.0.1 | 3306  | ONLINE       |
| 1            | 127.0.0.1 | 24801 | ONLINE       |
| 1            | 127.0.0.1 | 24802 | OFFLINE_SOFT |
| 1            | 127.0.0.1 | 24803 | ONLINE       |
| 1            | 127.0.0.1 | 3306  | ONLINE       |
+--------------+-----------+-------+--------------+
5 rows in set (0.01 sec)

Admin> UPDATE mysql_servers SET status='OFFLINE_HARD' WHERE hostname='127.0.0.1' AND port=24801 AND hostgroup_id=1;
Query OK, 1 row affected (0.00 sec)

Admin> SELECT hostgroup_id,hostname,port,status FROM mysql_servers;
+--------------+-----------+-------+--------------+
| hostgroup_id | hostname  | port  | status       |
+--------------+-----------+-------+--------------+
| 0            | 127.0.0.1 | 3306  | ONLINE       |
| 1            | 127.0.0.1 | 24801 | OFFLINE_HARD |
| 1            | 127.0.0.1 | 24802 | OFFLINE_SOFT |
| 1            | 127.0.0.1 | 24803 | ONLINE       |
| 1            | 127.0.0.1 | 3306  | ONLINE       |
+--------------+-----------+-------+--------------+
5 rows in set (0.00 sec)

十六、重新啓用脫機/禁用的後端服務器[Re-enabling an offline / disabled backend server]

要將離線的後端重新啓用，只需將其狀態更改回 ONLINE 就足夠了。

Admin> SELECT hostgroup_id,hostname,port,status FROM mysql_servers;
+--------------+-----------+-------+--------------+
| hostgroup_id | hostname  | port  | status       |
+--------------+-----------+-------+--------------+
| 0            | 127.0.0.1 | 3306  | ONLINE       |
| 1            | 127.0.0.1 | 24801 | OFFLINE_HARD |
| 1            | 127.0.0.1 | 24802 | OFFLINE_SOFT |
| 1            | 127.0.0.1 | 24803 | ONLINE       |
| 1            | 127.0.0.1 | 3306  | ONLINE       |
+--------------+-----------+-------+--------------+
5 rows in set (0.00 sec)

Admin> UPDATE mysql_servers SET status='ONLINE' WHERE status NOT IN ('ONLINE');  ==>這裏用了NOT，可根據實際情況修改過濾條件
Query OK, 2 rows affected (0.00 sec)

Admin> SELECT hostgroup_id,hostname,port,status FROM mysql_servers;
+--------------+-----------+-------+--------+
| hostgroup_id | hostname  | port  | status |
+--------------+-----------+-------+--------+
| 0            | 127.0.0.1 | 3306  | ONLINE |
| 1            | 127.0.0.1 | 24801 | ONLINE |
| 1            | 127.0.0.1 | 24802 | ONLINE |
| 1            | 127.0.0.1 | 24803 | ONLINE |
| 1            | 127.0.0.1 | 3306  | ONLINE |
+--------------+-----------+-------+--------+
5 rows in set (0.00 sec)

十七、刪除後端服務器[Removing a backend server]

ProxySQL允許將一個後端服務器徹底的刪除，只需要將其從mysql_servers表中完全刪除即可。

Admin> SELECT hostgroup_id,hostname,port,status FROM mysql_servers;
+--------------+-----------+-------+--------+
| hostgroup_id | hostname  | port  | status |
+--------------+-----------+-------+--------+
| 0            | 127.0.0.1 | 3306  | ONLINE |
| 1            | 127.0.0.1 | 24801 | ONLINE |
| 1            | 127.0.0.1 | 24802 | ONLINE |
| 1            | 127.0.0.1 | 24803 | ONLINE |
| 1            | 127.0.0.1 | 3306  | ONLINE |
+--------------+-----------+-------+--------+
5 rows in set (0.00 sec)

注意：雖然可以直接執行刪除操作，但是爲了操作的平滑、安全，數據的完整、可控，還是建議先修改狀態讓其軟下線，等待其上執行的所有SQL都結束後再執行後面的刪除動作。

Admin> UPDATE mysql_servers SET status='OFFLINE_SOFT' WHERE hostgroup_id=1 AND port IN (3306,24802,24803);
Query OK, 3 rows affected (0.00 sec)

Admin> SELECT hostgroup_id,hostname,port,status FROM mysql_servers;
+--------------+-----------+-------+--------------+
| hostgroup_id | hostname  | port  | status       |
+--------------+-----------+-------+--------------+
| 0            | 127.0.0.1 | 3306  | ONLINE       |
| 1            | 127.0.0.1 | 24801 | ONLINE       |
| 1            | 127.0.0.1 | 24802 | OFFLINE_SOFT |
| 1            | 127.0.0.1 | 24803 | OFFLINE_SOFT |
| 1            | 127.0.0.1 | 3306  | OFFLINE_SOFT |
+--------------+-----------+-------+--------------+
5 rows in set (0.00 sec)

Admin> DELETE FROM mysql_servers WHERE hostgroup_id=1 AND port IN (3306,24802,24803);
Query OK, 3 rows affected (0.00 sec)

Admin> SELECT hostgroup_id,hostname,port,status FROM mysql_servers;
+--------------+-----------+-------+--------+
| hostgroup_id | hostname  | port  | status |
+--------------+-----------+-------+--------+
| 0            | 127.0.0.1 | 3306  | ONLINE |
| 1            | 127.0.0.1 | 24801 | ONLINE |
+--------------+-----------+-------+--------+
2 rows in set (0.00 sec)

在ProxySQL內部，直接刪除後端服務和將其設置爲OFFLINE_HARD的方式相同。當執行LOAD MYSQL SERVERS TO RUNTIME時，
Hostgroup_Manager將檢測到後端服務器已被刪除，並在內部將其標記爲OFFLINE_HARD。

完畢！