Resource manager

In a single-user environment, the system can devote all resources to a single query and get the most efficient execution for that one query. However, in a environment where several concurrent queries are expected to run at once, there is tension between providing each query the maximum amount of resources (thereby getting fastest run time for that query) and serving multiple queries simultaneously with a reasonable run time. The Resource Manager provides options and controls for resolving this tension, while ensuring that every query eventually gets serviced and that true system limits are respected at all times.