A method and apparatus for processing a query is provided. A query for a set of Matching XML documents is received. A client may transmit the query for a set of XML documents to the database server. The database server transmits a request for the set of XML documents to a persistent storage. The persistent storage uses an index, at least in part, to obtain the set of XML documents sought by the query. The index stores a first set of entries comprising information about the location of elements, a second set of entries comprising information about element attributes, and a third set of entries comprising information about element values. In responding to a particular query, additional XML documents that are not indexed by the index may also be checked to determine if they correspond to the set of search criteria.