Efficient distribution of full-fledged XQuery

Ying Zhang, Nan Tang, Peter Boncz

Research output: Chapter in Book/Report/Conference proceedingConference contribution

9 Citations (Scopus)


We investigate techniques to automatically decompose any XQuery query into subqueries, that can be executed near their data sources; i.e., function-shipping. In this scenario, the subqueries being executed remotely may have XML nodevalued parameters or results, that must be shipped in some way. The main challenge addressed here is to ensure that the decomposed queries properly respect XML node identity and preserve structural properties, when (parts of) XML nodes are sent over the network, effectively copying them. We start by precisely characterizing the conditions, under which pass-by-value parameter passing causes semantic differences between remote execution of an XQuery expression and its local execution. We then formulate a conservative strategy that effectively avoids decomposition in such cases. To broaden the possibilities of query distribution, we extend the pass-byvalue semantics to a pass-by-fragment semantics, which keeps better track of node identities and structural properties. The pass-by-fragment semantics is subsequently refined to a pass-byprojection semantics by means of a novel runtime XML projection technique, which safely eliminates most semantic differences between the local and remote execution of an XQuery expression, and strongly reduces message sizes. The proposed techniques are implemented in XRPC, a simple yet efficient XQuery extension that enables function-shipping by adding a Remote Procedure Call mechanism to XQuery. Experiments on MonetDB/XQuery establish the performance potential of our XQuery decomposition techniques.

Original languageEnglish
Title of host publicationProceedings - 25th IEEE International Conference on Data Engineering, ICDE 2009
Number of pages12
Publication statusPublished - 8 Jul 2009
Event25th IEEE International Conference on Data Engineering, ICDE 2009 - Shanghai, China
Duration: 29 Mar 20092 Apr 2009

Publication series

NameProceedings - International Conference on Data Engineering
ISSN (Print)1084-4627


Other25th IEEE International Conference on Data Engineering, ICDE 2009


ASJC Scopus subject areas

  • Software
  • Signal Processing
  • Information Systems

Cite this

Zhang, Y., Tang, N., & Boncz, P. (2009). Efficient distribution of full-fledged XQuery. In Proceedings - 25th IEEE International Conference on Data Engineering, ICDE 2009 (pp. 565-576). [4812435] (Proceedings - International Conference on Data Engineering). https://doi.org/10.1109/ICDE.2009.79