Attribute grammars for scalable query processing on XML streams

Koch, Christoph; Scherzinger, Stefanie

doi:10.1007/s00778-005-0169-1

Cited by 32 publications

(15 citation statements)

References 26 publications

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“…Streamed evaluation means here that only one pass over the XML stream is used, and progressive evaluation means that the answers are output as soon as possible. Current streamed query processors, e.g., [8]- [14], are not designed to accomplish all these desiderata, their focus being in most cases a subset of them, possibly with additional desiderata, e.g., support for indexing and evaluating large sets of simple queries. We survey these processors in Section IX.…”

mentioning

confidence: 99%

SPEX: Streamed and Progressive Evaluation of XPath

Olteanu

2007

IEEE Trans. Knowl. Data Eng.

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Abstract-Streams are preferable over data stored in memory in contexts where data is too large or volatile, or a standard approach to data processing based on storing is too time or space consuming. Emerging applications such as publishsubscribe systems, data monitoring in sensor networks, financial and traffic monitoring, and routing of MPEG-7 call for querying streams. In many such applications, XML streams are arguably more appropriate than flat streams, for they convey (possibly unbounded) unranked ordered trees with labeled nodes. However, the flexibility enabled by XML streams in data modeling makes query evaluation different from traditional settings and challenging.This article describes SPEX, a streamed and progressive evaluation of XPath. SPEX compiles queries into networks of simple and independent transducers and processes XML streams with polynomial combined complexity. This makes SPEX especially suitable for implementation on devices with low-memory and simple logic as used, e.g., in mobile computing.

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confidence: 99%

SPEX: Streamed and Progressive Evaluation of XPath

Olteanu

2007

IEEE Trans. Knowl. Data Eng.

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“…More recently, it has been shown they are useful also for XML, and in particular for query languages and query processing (see, for instance, [39,41,40,29]). Extensive reviews of attribute grammar theory, implementation, systems, and applications are given in, e.g., [9,8,28,1,43].…”

Section: Related Workmentioning

confidence: 99%

On the complexity of regular-grammars with integer attributes

Manna

Scarcello

Leone

2011

Journal of Computer and System Sciences

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Regular grammars with attributes overcome some limitations of classical regular grammars, sensibly enhancing their expressiveness. However, the addition of attributes increases the complexity of this formalism leading to intractability in the general case. In this paper, we consider regular grammars with attributes ranging over integers, providing an in-depth complexity analysis. We identify relevant fragments of tractable attribute grammars, where complexity and expressiveness are well balanced. In particular, we study the complexity of the classical problem of deciding whether a string belongs to the language generated by any attribute grammar from a given class C (call it parse [C] ). We consider deterministic and ambiguous regular grammars, attributes specified by arithmetic expressions over {| |, +, −, ÷, %, * }, and a possible restriction on the attributes composition (that we call strict composition). Deterministic regular grammars with attributes computed by arithmetic expressions over {| |, +, −, ÷, %} are P-complete. If the way to compose expressions is strict, they can be parsed in L, and they remain tractable even if multiplication is allowed. Problem parse [C] becomes NP-complete for general regular grammars over {| |, +, −, ÷, %, * } with strict composition and for grammars over {| |, +, −, ÷, %} with unrestricted attribute composition. Finally, we show that even in the most general case the problem is in polynomial space.

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“…LR-AGs have been used in the context of XML streaming [13] and already Bochman [26] showed that all attribute values of an LR-AG can be computed in one left-to-right pass through the input tree. Accordingly, LR-AGs seem a natural candidate in our context.…”

Section: Factmentioning

confidence: 99%

Transforming XML Streams with References

Maneth

Ordóñez

Seidl³

2015

String Processing and Information Retrieval

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Many useful XML transformations can be formulated through deterministic top-down tree transducers. As soon as transducers process parts of the input repeatedly or in an order deviating from the document order, such transductions cannot be realized over the XML document stream with constant or even depthbounded memory. Here we show that by enriching streams by forward references every such transformation can be compiled into a stream processor with a space consumption depending only on the transducer and the depth of the XML document. This is remarkable because tree transducers have rich restructuring capabilities and can process copies of input subdocuments independently. Also, references allow one to produce output in a compressed form which is guaranteed to be linear in the size of the input (up to the space required for labels). Our model is designed so that without decompression, the output may again serve as the input of a subsequent transducer. In order to reduce the extra overhead incurred by references, we investigate three optimizations: (i) reference reuse to save space, (ii) multi-labels to avoid chains of references and (iii) inlining to limit the use of references to deviations of the document order.

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Attribute grammars for scalable query processing on XML streams

Cited by 32 publications

References 26 publications

SPEX: Streamed and Progressive Evaluation of XPath

SPEX: Streamed and Progressive Evaluation of XPath

On the complexity of regular-grammars with integer attributes

Transforming XML Streams with References

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