• $default - Contains any query that cannot be placed into an existing active queue. Every user in the system will use the default queue if necessary. The database administrator can create a queue and set it as the default queue, with the restriction that the queue must be a read-write queue (since the queue must be allowed to run any query). Only one default queue can exist in an active configuration. The default queue has no restrictions out of the box.

• $superuser - Contains any queries run by superusers. This queue has no restrictions and allows superusers to run queries unhindered. To use this queue, a user, group, or role must be authorized to the ‘$superuser’ queue.

• $express - Contains queries that are estimated to run extremely fast. The Express queue has no concurrency limit.  A query in the Express queue is moved back to an appropriate non-express queue if it exceeds three seconds of runtime.

• $system - Contains any query running against internal system tables, system views and procedures.