The University of Arizona

  TAU: τXQuery


We have designed a temporal XML query language, τXQuery, in which we add temporal support to XQuery by extending its syntax and semantics. Our goal is to move the complexity of handling time from the user/application code into the τXQuery processor. Moreover, we do not want to design a brand new query language. Instead, we made minimal changes to XQuery to ensure that τXQuery is both upward compatible and temporally upward compatible with XQuery. Using a stratum approach, we showed that we can build a τXQuery engine upon any existing XQuery engine. The major task of the τXQuery engine is to map τXQuery queries to semantically equivalent XQuery queries. We proposed six different time-slicing techniques for the translation. There are XML documents and queries that favors each approach.


Richard T. Snodgrass

Previous Graduate Student:
Dengfeng Gao


msr Sequenced Stored Procedures in SQL
Microsoft Corporation unrestricted grant
August 2003 to July 2004 (R. T. Snodgrass, PI)


Dengfeng Gao, Supporting the Procedural Component of Query Languages over Time-Varying Data, Doctoral Dissertation, Computer Science Department, University of Arizona, April 29, 2009. (pdf)

Dengfeng Gao and Richard T. Snodgrass, "Temporal Slicing in the Evaluation of XMLQueries," in Proceedings of the International Conference on Very Large Databases, Berlin, September 2003. (pdf)

Dengfeng Gao and Richard T. Snodgrass, "Syntax, Semantics, and Query Evaluation of the τXQuery Temporal XML Query Language," TimeCenter TR-72, March 2003. (pdf)


MarkLogic's MarkLogic Server product stores XML documents as a transaction-time database and supports transaction timeslice queries in XQuery (termed "point-in-time queries"), almost identically to that proposed in τXQuery.

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