1. A computer program product comprising a computer-readable storage medium storing computer-executable code for a travel reservation search engine for providing travel search results, the computer-executable code comprising: a query interface module configured to receive from the user a search request for travel reservation information; a constraint evaluation module configured to construct a first query based upon one or more constraints associated with the search request, such that the first query has at least a threshold probability, based upon the one or more constraints, of returning a successful search result; and a website query module configured to execute the first query to obtain a set of first phase query results.