22. The system of claim 17 , wherein generating the one or more query templates includes: for at least one of the embedded coding fragments, counting a number of other structured documents hosted on the website that include the embedded coding fragment; and generating the query template for the embedded coding fragment in response to determining that the number of other structured documents that are hosted on the website and that include the embedded coding fragment that satisfies a template qualification value.
17. A system, comprising: one or more computers configured to perform operations comprising: receiving a set of seed queries associated with a structured document, the structured document including embedded coding and being hosted on a website, each seed query including one or more terms; identifying one or more embedded coding fragments from the structured document for each seed query, each identified embedded coding fragment for a seed query specifying a structure of a portion of the structured document that includes at least one term of the seed query; generating one or more query templates, each query template corresponding to at least one identified embedded coding fragment, the query template including the structure of the corresponding at least one embedded coding fragment and a generative rule to be used in generating one or more candidate synthetic queries; generating the one or more candidate synthetic queries using the one or more query templates and other structured documents hosted on the website, the generating comprising, for each query template: identifying a portion of a particular structured document hosted on the website that includes the structure specified by the corresponding embedded coding fragment; and generating a candidate synthetic query using text contained in the portion of the particular structured document and specified by the generative rule; measuring a performance in a search operation of each of the one or more candidate synthetic queries; designating as a synthetic query a candidate synthetic query that has a performance measurement that exceeds a performance threshold; and storing the designated synthetic query in a query store.