Read-only mode

Read-only mode for connection disables any index and global modifications. So, queries like create, drop, all kinds of alter, attach, optimize, data modifications queries, such as insert, replace, delete, update and others will all be rejected. Changing daemon-wide settings via SET GLOBAL is also not possible in this mode.

You still can perform all search operations, generate snippets and run CALL PQ queries. Also, you can modify local (connection-wide) settings.

You can check, whether your current connection is read-only or not by executing show variables like 'session_read_only' statement. Value 1 means read-only, 0 - usual (not read-only).

Activation

Normally you define a separate listen directive in read-only mode by adding suffix _readonly to it, but you can also, do it interactively for the current connection by executing SET ro=1 statement via sql.

Deactivation

If you’re connected to a vip socket, you can execute SET ro=0 (even if the socket you are connected to was defined read-only in config, not interactively), and the connection will switch to usual (not read-only) mode with all modifications allowed.

For usual (non-VIP) connections escaping read-only mode is only possible by reconnecting, if it was set read-only interactively, or updating the configuration file and restarting the daemon.