14. The method of claim 12 , wherein: the facet hierarchy includes a plurality of facets; the pre-defined cube structure includes pre-defined dimensions; and determining whether the pre-defined cube structure corresponds to the facet hierarchy comprises determining whether each facet of the facet hierarchy maps to a pre-defined dimension of the pre-defined cube structure.
15. The method of claim 14 , wherein: the pre-defined cube structure further includes a plurality of pre-defined measures; and modifying the pre-defined cube structure comprises re-calculating a pre-defined measure based on the documents that satisfy the query.