20. The one or more non-transitory storage media of claim 19 , wherein the instructions, when executed by the one or more processors, further cause, if the particular query is associated with the lowest cost relative to other queries in the set of one or more subsequent queries, then executing the particular query.
19. The one or more non-transitory storage media of claim 17 , wherein the instructions, when executed by the one or more processors, further cause: receiving an initial query; and generating, based on the initial query, a set of one or more subsequent queries, wherein the set of one or more subsequent queries includes the particular query.