Consistent Critical Read (CCR) Filter detects when a statement modifies the database, and it attaches routing hints to any subsequent statements, so they get routed to the master.
See also: Filters for MariaDB MaxScale 6
Additional information on this topic may be found in the MariaDB Public Knowledge Base.
This page shows information specific to MariaDB SkySQL. Information for non-SkySQL use can be found on the ccrfilter page in the MariaDB Enterprise Documentation.