It would be good to be able to specify priorities for operations. For instance one query may be more important then another one and if they are running at the same time it would be good for the more important one to get a bigger slice of the resources. Additionally this is a requirement for the STIG requirement SRG-APP-000245-DB-000132:

"A variety of technologies exist to limit, or in some cases, eliminate the effects of DoS attacks. For example, boundary protection devices can filter certain types of packets to protect devices on an organization’s internal network from being directly affected by DoS attacks. Employing increased capacity and bandwidth combined with service redundancy may reduce the susceptibility to some DoS attacks. Some of the ways databases can limit their exposure to DoS attacks are through limiting the number of connections that can be opened by a single user and database clustering."