With the exception of the three configuration variables described here, ProxySQL will only parse the configuration files the first time it is started, or if the proxysql.db file is missing for some other reason.
If we want to change any of this data we need to do so via ProxySQL’s admin interface and then save them to disk. That’s fine if ProxySQL is running, but what if it won’t start because of these values?
For example, perhaps we accidentally configured ProxySQL to run on port 3306 and restarted it, but there’s already a production MySQL instance running on this port. ProxySQL won’t start, so we can’t edit the value that way:
1 | 2018-10-02 09:18:33 network.cpp:53:listen_on_port(): [ERROR] bind(): Address already in use |
We could delete proxysql.db and have it reload the configuration files, but that would mean any changes we didn’t mirror into the configuration files will be lost.
Another option is to edit ProxySQL’s database file using sqlite3:
1 2 3 4 5 6 7 | [root@centos7-pxc57-4 ~]# cd /var/lib/proxysql/ [root@centos7-pxc57-4 proxysql]# sqlite3 proxysql.db sqlite> SELECT * FROM global_variables WHERE variable_name='mysql-interfaces'; mysql-interfaces|127.0.0.1:3306 sqlite> UPDATE global_variables SET variable_value='127.0.0.1:6033' WHERE variable_name='mysql-interfaces'; sqlite> SELECT * FROM global_variables WHERE variable_name='mysql-interfaces'; mysql-interfaces|127.0.0.1:6033 |
Or if we have a few edits to make we may prefer to do so with a text editor:
1 2 3 4 5 | [root@centos7-pxc57-4 ~]# cd /var/lib/proxysql/ [root@centos7-pxc57-4 proxysql]# sqlite3 proxysql.db sqlite> .output /tmp/global_variables sqlite> .dump global_variables sqlite> .exit |
The above commands will dump the global_variables table into a file in SQL format, which we can then edit:
1 2 3 4 5 | [root@centos7-pxc57-4 proxysql]# grep mysql-interfaces /tmp/global_variables INSERT INTO “global_variables” VALUES(‘mysql-interfaces’,’127.0.0.1:3306’); [root@centos7-pxc57-4 proxysql]# vim /tmp/global_variables [root@centos7-pxc57-4 proxysql]# grep mysql-interfaces /tmp/global_variables INSERT INTO “global_variables” VALUES(‘mysql-interfaces’,’127.0.0.1:6033’); |
Now we need to restore this data. We’ll use the restore command to empty the table (as we’re restoring from a missing backup):
1 2 3 4 | [root@centos7-pxc57-4 proxysql]# sqlite3 proxysql.db sqlite> .restore global_variables sqlite> .read /tmp/global_variables sqlite> .exit |
Once we’ve made the change, we should be able to start ProxySQL again:
1 2 3 4 5 6 7 8 | [root@centos7-pxc57-4 proxysql]# /etc/init.d/proxysql start Starting ProxySQL: DONE! [root@centos7-pxc57-4 proxysql]# lsof -I | grep proxysql proxysql 15171 proxysql 19u IPv4 265881 0t0 TCP localhost:6033 (LISTEN) proxysql 15171 proxysql 20u IPv4 265882 0t0 TCP localhost:6033 (LISTEN) proxysql 15171 proxysql 21u IPv4 265883 0t0 TCP localhost:6033 (LISTEN) proxysql 15171 proxysql 22u IPv4 265884 0t0 TCP localhost:6033 (LISTEN) proxysql 15171 proxysql 23u IPv4 266635 0t0 TCP *:6032 (LISTEN) |
While you are here
You might enjoy my recent post Using ProxySQL to connect to IPV6-only databases over IPV4
You can download ProxySQL from Percona repositories, and you might also want to check out our recorded webinars that feature ProxySQL too.
Comment (1)
Good content. Nice article. Kindly read Farm house for rent in Mysore
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