NDLI: Efficient computation of aggregate structural joins

Content Provider	IEEE Xplore Digital Library
Author	Kaiyang Liu Lochovsky, F.H.
Copyright Year	2003
Description	Author affiliation: Dept. of Comput. Sci., Univ. of Sci. & Technol., Hong Kong, China (Kaiyang Liu; Lochovsky, F.H.)
Abstract	Although several XML query-processing techniques have been proposed to do structural joins, no work has been done to handle aggregate structural join, which computes the aggregate value for two given XML element sets. One important kind of aggregate structural join is to determine the exact selectivity of a structural join, which proves to be crucial for overall path expression optimization and on-line systems. Related work has been done to estimate the selectivity of a path expression by applying summary techniques for XML data based on either tree simplification or a Markov model. However, because of either space restrictions or performance issues (for example, previous approaches may need to store the whole XML tree to answer an aggregate structural join), they are not applicable for aggregate structural joins. In this paper, we consider a modified aggregate B-tree, which we call a XA-tree, to index the aggregate attribute values of XML elements. Since it is based on the B-tree, the XA-tree supports query and update efficiently and places little additional burden on database administrators. Two basic algorithms are proposed to compute aggregate structural joins efficiently by utilizing the XA-tree. Furthermore, a heuristic is also proposed to further improve the performance significantly. Extensive experiments have confirmed that our approaches greatly outperform competitors by an order of magnitude.
Sponsorship	Universita di Roma 'La Sapienza' Microsoft Res. IBM WebSphere Banca d'Italia European Res. Consortium for Informatics and Mathematics
Starting Page	21
Ending Page	30
File Size	440306
Page Count	10
File Format	PDF
ISBN	0769519997
DOI	10.1109/WISE.2003.1254465
Language	English
Publisher	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Publisher Date	2003-12-12
Publisher Place	Italy
Access Restriction	Subscribed
Rights Holder	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subject Keyword	Aggregates XML Computer science Databases Markup languages Internet Delay Search engines Information systems Data engineering
Content Type	Text
Resource Type	Article

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