Accelerating queries by pruning XML documents

Bressan, Stéphane; Catania, Barbara; Lacroix, Zoé; Li, Yingguang; Maddalena, Anna

doi:10.1016/j.datak.2004.12.003

Cited by 9 publications

(17 citation statements)

References 21 publications

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“…Section VI then introduces a new runtime XML projection technique, which we use to generate messages that conserve all needed structural relationships between transferred XML nodes, and thus allow even more freedom in query decomposition. As a runtime technique, it is able to prune XML data much more than previously described compile-time projections [3], [5], [15]. An evaluation of the performance benefits of our techniques is given in Section VII.…”

Section: Introductionmentioning

confidence: 91%

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Efficient Distribution of Full-Fledged XQuery

Zhang

Tang

Boncz

2009

2009 IEEE 25th International Conference on Data Engineering

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Abstract-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.

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Section: Introductionmentioning

confidence: 91%

“…[5] introduces a precise XML pruning technique for a subset of XQUERY FLWOR expressions, based on the apriori knowledge of a data guide for underlying XML data. However, it does not handle XPATH predicates, backward axes and XQUERY-like languages.…”

Section: Evaluation In Monetdb/xquerymentioning

confidence: 99%

Efficient Distribution of Full-Fledged XQuery

Zhang

Tang

Boncz

2009

2009 IEEE 25th International Conference on Data Engineering

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“…XML projection [21] drastically reduces the size of the data model representation using compile-time query characterization. Bressan et al [5] introduces a precise XML pruning technique for a subset of XQUERY FLWOR expressions, based on the a priori knowledge of a data guide for underlying XML data. However, it does not handle XPATH predicates, backward axes, and XQUERYlike languages.…”

Section: Related Workmentioning

confidence: 99%

“…As mentioned in Section 4, in the definition of Dðv x Þ, 5 we use a wildcard URIÃ if the document name is an expression. All paths start with doc(uri::v i ), thus, they identify both document URI and the vertex v i where it is loaded.…”

Section: Extending Projected Xmlmentioning

confidence: 99%

“…Section 6 introduces a new runtime XML projection technique, which we use to generate messages that conserve all needed structural relationships between transferred XML nodes, and thus allow even more freedom in query decomposition. As a runtime technique, it is able to prune XML data much more than previously described compile-time projections [2], [5], [18]. In Section 7.1, we discuss how updating queries can be handled, both in the normal XQUF semantics, as well as under an extension, in which we allow nonlocal documents to be updated.…”

Section: Introductionmentioning

confidence: 99%

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Projective Distribution of XQuery with Updates

Zhang

Tang

Boncz

2010

IEEE Trans. Knowl. Data Eng.

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We investigate techniques to automatically decompose any XQuery query-including updating queries specified by the XQuery Update Facility (XQUF)-into subqueries, that can be executed near their data sources, i.e., function-shipping. 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-by-value 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. Finally, we discuss how these techniques can be used for updating queries, both under the standard W3C XQUF specification, as well as under an extended semantics that allows to update remote documents. 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.

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Efficient keyword search over virtual XML views

et al. 2009

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Emerging applications such as personalized portals, enterprise search and web integration systems often require keyword search over semi-structured views. However, traditional information retrieval techniques are likely to be expensive in this context because they rely on the assumption that the set of documents being searched is materialized. In this paper, we present a system architecture and algorithm that can efficiently evaluate keyword search queries over virtual (unmaterialized) XML views. An interesting aspect of our approach is that it exploits indices present on the base data and thereby avoids materializing large parts of the view that are not relevant to the query results. Another feature of the algorithm is that by solely using indices, we can still score the results for queries over the virtual view, and the resulting scores and rank order are the same as if the view was materialized. Our performance evaluation using the INEX data set in the Quark [8] open-source XML database system indicates that the proposed approach is scalable and efficient.

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Accelerating queries by pruning XML documents

Cited by 9 publications

References 21 publications

Efficient Distribution of Full-Fledged XQuery

Efficient Distribution of Full-Fledged XQuery

Projective Distribution of XQuery with Updates

Efficient keyword search over virtual XML views

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