61. The system of claim 60 in which the one or more indexes comprise an index on a path identifier, an index on the document identifier and a start position, or an index on the document identifier, start position, and node level.
61. The system of claim 60 in which the one or more indexes comprise an index on a path identifier, an index on the document identifier and a start position, or an index on the document identifier, start position, and node level. 62. The system of claim 61 in which the path identifier corresponds to a key to a path entry containing a full path for the node, the path entry resides in a separate table, and the one or more indexes comprise an index on path identifiers or a unique index on reverse paths.