1. One or more computer-readable media storing computer-executable instructions that, when executed, cause one or more processors to perform acts comprising: modeling query behavior over time to create a time-aware query model; modeling uniform resource locator (URL) behavior over time to create a time-aware URL model; determining a query-URL relationship based at least in part on the time-aware query model and the time-aware URL model; performing a search in response to a query; and ranking results of the search according to the query-URL relationship.