Working Draft

Date: Feb. 15, 2001
Link: http://www.w3.org/TR/query-algebra/
Source Author or Organization: W3C

Warning: this document is deprecated and has been replaced by http://www.w3.org/TR/query-semantics/.

This document is a first Working Draft of a specification defining XML Query Algebra.

The XML Query Data Model defines the information contained in the input to an XML Query processor. The XML Query Data Model and XML Query Algebra together provide a semantics of the XML Query Language.

In the database world, it is common to translate a query language (such as SQL) into an algebra to provide semantics for the query language and to support query optimization. It is also common for a query language to exploit schemas or types.

XML Query algebra is statically typed (using both Document Type Definitions and XML Schemas) in order to make it possible to determine and validate the output type of a query on a document based on its input type at compile time rather than at runtime.

A tutorial is also included in this document which exposes the reader to the entire algebra and demonstrates how it can be used to construct queries. The algebra's other components are also described in detail.