Lazy analytics: Let other queries do the work for you

We propose a class of query, called a derange query, that maps a function over a set of records and lazily aggregates the results. Derange queries defer work until it is either convenient or necessary, and, as a result, can reduce total I/O costs of the system. Derange queries operate on a view of the data that is consistent with the point in time that they are issued, regardless of when the computation completes. They are most useful for performing calculations where the results are not needed until some future deadline. When necessary, derange queries can also execute immediately. Users can view partial results of in-progress queries at low cost.