1. At least one computer-readable storage medium having computer-executable instructions stored thereon which, when executed by a computer system, cause the computer system to perform a method comprising: instantiating at least one iterator in response to a search request, wherein the iterator includes fixed state information that remains constant over a life of the iterator, and includes dynamic state information that is updated over the life of the iterator; traversing the iterator through at least a portion of at least one postings list in connection with performing the search request; updating at least one instance of the dynamic state information, in response to traversing the iterator through at least the portion of the postings list; and evaluating whether to create a checkpoint of the iterator, wherein the checkpoint includes at least a representation of the dynamic state information.