Tables in information_schema are treated as a normal tables

The tables in the information_schema are treated like normal user-created tables and get route to any of the nodes where they are found. This makes it hard to use queries that target these tables in conjunction with other queries. A JOIN to an information_schema still works correctly and can sometimes be used as a workaround.

An improvement to the current behavior would be that if a default database is set and the query only targets tables that are "system tables" (mysql, information_schema, sys, etc.), the query should be routed based on the default database instead. If no default database is set but a previous query was executed, it could be routed to that node. This would at least allow "priming" the queries by doing a SHOW TABLES IN <db> after which the next query to information_schema would then be routed in the correct manner.