1. A method comprising: determining to store a spatial document index for a corpus of documents, wherein the spatial document index indexes documents in the corpus according to spatial references found within the documents; determining to store a plurality of spatial keyword document indexes for the corpus of documents, wherein the spatial keyword document indexes are derived from the spatial document index, are for a different keyword, and indexes those documents among the corpus that are responsive to that keyword; and intersecting a portion of the spatial document index and selected indexes among the plurality of spatial keyword document indexes to identify a result set of those documents from among the corpus of documents that are responsive to a query.
10. The method of claim 1 , wherein at least one of the documents of the result set contains the said one or more keywords specified in the query and is responsive to the spatial information specified in the query.