MonetDB/XQuery integrates the Pathfinder compiler into the MonetDB product and furthermore extends it with runtime extensions for offline and online shredding, serialization (with multiple serialization modes), efficient path step algorithms such as Staircase Join, and support for updates.
MonetDB/XQuery inherits the scalability of its database back-end: you may feed XML documents beyond 1GB size into the system and still expect reasonable, interactive query response times (for example, with the XMark benchmark).
SQL Code Generator
Pathfinder's SQL code generator is the ideal playground for everybody who is interested to extend his favourite database with XML support. We have tested the generated SQL code on DB2 v9, Microsoft SQL Server and PostgreSQL with different XML encodings. For DB2 and SQL Server B-tree indexes faithfully speed up the range predicates that implement XPaths location step semantics. (The combination of Pathfinder and DB2 was even able to outperform DB2's built-in XQuery support on larger XML documents.)
Pathfinder itself comes bundled with MonetDB/XQuery and allows to generate MIL code for MonetDB, SQL code, or returns the algebraic query plan in an XML format (see next paragraph). Pathfinder furthermore allows to import an algebra plan (in XML format) for further processing or visualization. Based on this mechanism, e.g., Ferry optimizes its query plans and generates SQL code.
Extensibility of Pathfinder
Pathfinder is a re-targetable compiler that is able to produce optimized algebra plans (in XML format). These plans feature normal table algebra operators (such as select, project, join, ...) and some XML specific operators like e.g, path joins, node access. The XML specific operators are the operators interacting with the encoded XML document---they keep the interface to the encoded XML document abstract. This allows new backends to choose a XML encoding that works best.
Binary and Source Distributions
MonetDB/XQuery is available for a large number of plattforms, including Linux (32 and 64 bits), Windows® (NT, 2000,XP, Server 2003), and MacOS X. From time to time we release distribution versions of MonetDB/XQuery. They are available via the MonetDB download page: http://monetdb.cwi.nl/XQuery/. This is the recommended way to acquire the MonetDB/XQuery sources.