10. A method, comprising: receiving a query expression specifying a set of information to be retrieved; checking for the presence of a cache file related to a database file, the database file including at least the specified set of information, wherein the cache file comprises one or more subsets of information from the database file and one or more query expressions, wherein each one of the one or more subsets of information is stored in the cache file in association with a different one of the one or more query expressions, and wherein each one of the one or more subsets of information is a result of parsing the database file according to a corresponding one of the one or query expressions; in response to determining that the cache file is present: determining whether the specified set of information is present in the cache file; in response to determining that the specified set of information is present in the cache file: determining whether the cache file is valid, wherein said determining whether the cache file is valid comprises examining a currency token stored in association with the cache file, wherein the currency token indicates whether the cache file is current, wherein the currency token includes an attribute of the database file, and wherein the attribute describes the database file at a time when the database file was parsed according to the one or more query expressions that are stored in the cache file; in response to determining that the cache file is valid: retrieving the specified set of information from an entry in the cache file, wherein the entry is associated with one of the one or more query expressions which matches the retrieved query expression.
10. A method, comprising: receiving a query expression specifying a set of information to be retrieved; checking for the presence of a cache file related to a database file, the database file including at least the specified set of information, wherein the cache file comprises one or more subsets of information from the database file and one or more query expressions, wherein each one of the one or more subsets of information is stored in the cache file in association with a different one of the one or more query expressions, and wherein each one of the one or more subsets of information is a result of parsing the database file according to a corresponding one of the one or query expressions; in response to determining that the cache file is present: determining whether the specified set of information is present in the cache file; in response to determining that the specified set of information is present in the cache file: determining whether the cache file is valid, wherein said determining whether the cache file is valid comprises examining a currency token stored in association with the cache file, wherein the currency token indicates whether the cache file is current, wherein the currency token includes an attribute of the database file, and wherein the attribute describes the database file at a time when the database file was parsed according to the one or more query expressions that are stored in the cache file; in response to determining that the cache file is valid: retrieving the specified set of information from an entry in the cache file, wherein the entry is associated with one of the one or more query expressions which matches the retrieved query expression. 11. The method of claim 10 , wherein said receiving the query expression comprises receiving one or more of an XQuery expression or an XPath expression.