eXist is an Open Source native XML database with pluggable storage backends and support for fulltext search. XML is either stored in the internal, native XML-DB or an external RDBMS.
Version 0.7.1 adds new features for fulltext-searching: There's now a near-function for index-based, tolerant queries on phrases and support for regular expressions in search patterns. Some major bugs related to namespace processing have been fixed and a problem in the storage backend resulting in damaged database files has been solved.