J.F. Naughton et al., "The Niagara Internet Query System," IEEE Data Eng. Bulletin,vol. 24, no. 2, 2001, pp. 27--33.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....Madison, Wisconsin, USA Copyright 2002 ACM 1 58113 497 5 02 06 . 5.00. results. These assumptions break down in newer federated and Internet based query environments, that are targeted by the Telegraph dataflow engine [25] and other systems that support queries over remote data sources (e.g. [14, 19]) In these environments, di#erent data sources of varying performance can be joined in a single query, and the production of a single complete output row may be blocked by delays or rate mismatches across sources. In such scenarios, useful results from fast sources could still be made available ....

....relationships between sources. As a result, public interfaces for Internet query processors typically allow queries to be specified imprecisely. In the FFF demo we provided a set of broad, canned queries that we believed would satisfy a large number of users. The Niagara Internet Query System [19] suggests an interface where sources in a query are automatically generated by looking up user specified keywords in a catalog of all sources. The cooperative database literature has long argued for looser modes of query specification (e.g. 28, 18, 7] where the system aids the user in ....

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J. F. Naughton et al. The Niagara Internet query system. IEEE Data Engg. Bull., 24(2), 2001.

....requested. In fact, in a document representation of the database, a sub tree corresponds to a contiguous fragment of the document.As such, the determination of parent child and ancestor descendent containment relationships is a very frequent operation in XML query processing. It has been observed [43,12,2] that it is possible to associate a numeric start and end label with each data node in the database, defining a corresponding interval between these labels such that every descendant node has an interval that is strictly included in its ancestors interval. If each node is also labeled with its ....

J. Naughton, D. DeWitt, D. Maier, et al (2002) The Niagara internet query system. Available at: http://www.cs.wisc.edu/niagara/papers/ NIAGARAVLDB00.v4.pdf

....to effectively tap into the large amounts of data stored in XML databases around the globe are going to be crucial to fulfilling the full potential of XML and enabling Internet scale applications. Realizing such Internet scale XML query processors (like, e.g. Xyleme (www.xyleme.com) or Niagara [17]) in turn, hinges on providing effective support for high level, declarative XML query languages. A variety of languages have been proposed for querying semistructured and XML databases, including XQuery [4] Lorel [15] and UnQL [3] A common characteristic of all existing language proposals, is ....

J.F. Naughton, D.J. DeWitt, D. Maier, et al. "The Niagara Internet query system". IEEE Data Eng. Bulletin, 24(2).

....binding cross product; see [2, 3] for details. The techniques described in [17] have the further advantage of not being in memory, but their heuristic approach can not guarantee the correct answer. Other related work. There have been several attempts to add keyword search to XML query languages [8, 11, 12], but these languages support only boolean lters, not ranked query results. More closely related are XXL [16] an SQL like language, XIRQL [9] and Hayashi et al. s XML query language [10] These languages return results ranked by textual similarity, but they do not appear to support similarity ....

J. Naughton, D. DeWitt, and D. Maier. The Niagara Internet query system, 2000. http://www.cs.wisc.edu/niagara.

....the XML Query working group ( 24] Finally, Section 0 concludes this paper and discusses future work. 2. Related Work There exist two major approaches to manage and query XML documents. The first approach uses special purpose query engines and repositories for semi structured data [15] 20] [21]. These database systems are built from scratch for the specific purpose of storing and querying XML documents. This approach, however, has two potential disadvantages. Firstly, native XML database systems do not harness the sophisticated storage and query capability already provided by existing 2 ....

Naughton J., et al, The Niagara Internet Query System, IEEE Data Eng. Bulletin, 24(2), June 2001, 27-33.

....predates XML, and lacks the clear structure and elegance of the recently developed XML query languages such as XML QL. Furthermore, although an in depth comparison is beyond the scope of this paper, it appears that this older work resulted in less expressive languages. In parallel to our work, [NDM 00] have proposed to combine XML querying with an IR search engine. However, the IR capabilities considered there are limited to simple containment predicates and seem to follow a Boolean retrieval paradigm (at least [NDM 00] does not mention anything about support for ranked retrieval) The rest ....

....older work resulted in less expressive languages. In parallel to our work, NDM 00] have proposed to combine XML querying with an IR search engine. However, the IR capabilities considered there are limited to simple containment predicates and seem to follow a Boolean retrieval paradigm (at least [NDM 00] does not mention anything about support for ranked retrieval) The rest of the paper is organized as follows. Section 2 presents an example scenario. Section 3 presents our language in more detail. Section 4 sketches a prototype implementation based on Oracle8i interMedia and section 5 shows ....

J. Naughton, D. DeWitt, D. Maier, et al.: The Niagara Internet Query System. http://www.cs.wisc.edu/niagara/Publications.html 25

....opportunities arise and how, given the new cost model, we can perform 2 more detailed query optimization for specific time points in the query execution process. We validate this new framework through experiments with the Niagara system. 1. 1 Motivation In the context of the Niagara Project [3, 8, 12] we have implemented an Internet Query Engine over network resident, streaming, XML information sources. We experimented with various ways of organizing plans involving multiple join operations, and measured their performance by keeping track of the exact time at which each individual output ....

....department was fixed to a percentage of the total number of students appearing in the file, so each equi join predicate had the same estimated selectivity. For our experiments, we kept this selectivity at 15 . All experiments were performed using the current version of the Niagara Query Engine [3, 8, 12] 17 department student name lastname firstname phone e mail address city state zip office url gpa Figure 6: The XML schema used in our experiments developed at the University of Wisconsin Madison. The hardware setup involved a Pentium III processor operating on 800 MHz with 256 MB of ....

Je#rey Naughton, David DeWitt, and David Maier et. al. The Niagara Internet Query System. Submitted for Publication. 24

....is, they contain at least one book authored by Smith. We present an inverse indexing technique that indexes content words and element tags in XML documents by taking into account the element structure of the documents. Inspired by the text in context XML search engine of the Niagara project [16, 15], we present a formally veri able framework for indexing XML data that is more general than that of Niagara. Like Niagara, our framework uses two inverted lists, one to index content words and another to index XML tags for all web accessible XML documents. The main contribution of our method is ....

J. Naughton, D. DeWitt, and D. Maier. The Niagara Internet Query System . Submitted for publication. Available at http://www.cs.wisc.edu/niagara/, 2000.

....by this is precise indexing of web accessible XML data. We present an inverse indexing technique that indexes content words and element tags in XML documents by taking into account the element structure of the documents. Inspired by the textin context XML search engine of the Niagara project [27], we present a framework for indexing XML data that is more precise, easier to implement, and more ecient than that of Niagara. Like Niagara, our framework uses two inverted lists, one to index content words and another to index XML tags for all web accessible XML documents. Unlike Niagara, ....

....the actual paths may also be challenging since XML OQL supports XML projections over any OQL expression. Our previous work on normalization and query unnesting [16] would be very valuable on extracting these paths. Inspired by the text in context XML search engine of the Niagara project [27] and its algebra, SEQL, we present a framework for indexing XML data that is more precise, easier to implement, and more ecient than that of Niagara. Like Niagara, our framework uses two inverted lists, word index and tag index, one for indexing content words in XML elements and another for ....

[Article contains additional citation context not shown here]

J. Naughton, D. DeWitt, and D. Maier. The Niagara Internet Query System . Submitted for publication. Available at http://www.cs.wisc.edu/niagara/papers/NIAGRAVLDB00.v4.pdf, 2000.

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Naughton, J., DeWitt, D., Maier, D., and others. "The Niagara Internet Query System", 2000, www.cs.wisc.edu/niagara/Publications.html.

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Jeffrey Naughton, David DeWitt, and David Maier. The Niagara Internet Query System. Available from http://www.cs.wisc.edu/niagara/papers/NIAGRAVLDB00.v4.pdf. 1999.

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J. Naughton, D. DeWitt, D. Maier, et al. The Niagara Internet Query System. In IEEE Data Engineering Bulletin, 2001.

....example, all of Shakespeare s plays can be marked up and stored as XML documents. With a large amount of data represented as XML documents, it becomes necessary to store and query these XML documents. To address this problem, there has been work done on building native XML database systems [6][9]. These database systems are built from scratch for the specific purpose of storing and querying XML documents. This approach, however, has two potential disadvantages. Firstly, native XML database systems do not harness the sophisticated storage and query capability already provided by existing ....

J. Naughton, et al., "The Niagara Internet Query System", IEEE Data Engineering Bulletin, Vol. 24, No. 2, 2001.

.... previous techniques (nest is blocking and appears deep in the query tree) Neither can they handle a query that constantly monitors the average price of BMW cars posted in the Internet except those that appear on salvage lists (average and except are blocking) The Niagara Internet Query System [6] contains a general framework for producing partial results for queries involving blocking operators. The framework allows blocking and nonblocking operators to be arbitrarily intermixed in the query tree, i.e. non blocking operators can operate on the results of blocking operators and ....

....key requirements on the implementations of both blocking and non blocking operators. In this paper, we identify alternative algorithms and implementations satisfying the key requirements and evaluate their performance using the Niagara system. This paper complements the architectural overview in [6] and justifies the implementation decision made therein. The rest of the paper is organized as follows. In Section 2, we formally define partial results and list the properties operator implementations need to satisfy in order to produce partial results. In Section 3, we identify alternative ....

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J. Naughton, et. al., "The Niagara Internet Query System", submitted for publication.

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J.F. Naughton et al., "The Niagara Internet Query System," IEEE Data Eng. Bulletin,vol. 24, no. 2, 2001, pp. 27--33.

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J. Naughton, D. DeWitt, D. Maier, and others. "The Niagara Internet Query System", IEEE Data Engineering Bulletin, Vol. 24, No. 2, 2001, pp. 27-33.

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Naughton, Jeffrey; DeWitt, David; Maier, David; and others. 2000. "The Niagara Internet Query System." http://www.cs.wisc.edu/niagara/Publications.html.

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J. Naughton, et al. The Niagara Internet Query System. In IEEE Data Engineering Bulletin, 24(2), 2001.

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J. Naughton, D. DeWitt, D. Maier, and others. "The Niagara Internet Query System", IEEE Data Engineering Bulletin, Vol. 24, No. 2, 2001, pp. 27-33.

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Naughton, J.; DeWitt, D.; Maier, D. and others. 2001. "The Niagara Internet Query System", IEEE Data Engineering Bulletin, Vol. 24, No. 2, pp. 27-33.

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Naughton, J. ; DeWitt, D. ; Maier, D. ; and others. 2001. "The Niagara Internet Query System", IEEE Data Engineering Bulletin, Vol. 24, No. 2, pp. 27-33.

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J. Naughton, D. DeWitt, D. Maier, and others. "The Niagara Internet Query System", IEEE Data Engineering Bulletin, Vol. 24, No. 2, 2001, pp. 27-33.

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J. Naughton, D. DeWitt, D. Maier, et al. The Niagara Internet Query System. IEEE Data Eng. Bulletin, 24(2).

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J. F. Naughton, D. J. DeWitt, and D. M. et al. "The Niagara Internet query system". IEEE Data Engineering Bulletin, 24(2), 2001.

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J.F. Naughton, D.J. DeWitt, D.Maier, et al. "The Niagara Internet Query System". IEEE Data Engineering Bulletin, 24(2), 2001.

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J.F. Naughton et al., "The Niagara Internet Query System," IEEE Data Eng. Bulletin,vol. 24, no. 2, 2001, pp. 27--33.

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Naughton, J.; DeWitt, D.; Maier, D.; and others, "The Niagara Internet Query System", IEEE Data Engineering Bulletin, 24(2), 2001, pp. 27-33.

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J. Naughton et al, "The Niagara Internet Query System", IEEE Data Eng. Bulletin, 24(2), 2001.

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Jeffrey Naughton, David Dewitt, David Maier, Jianjun Chen, Jaewoo Kang, ~ Naveen Prakash, Jayavel Shanmugasundaram, Ravishankar Ramamurthy, Yuan Wang, ~ Rushan Chen, Leonidas Galanis, Qiong Luo, Feng Tian, Chun Zhang, Bruce Jackson, ~ Anurag Gupta, and Kristin Tufte. The Niagara internet query system, 2000. Available at http://www.cs.wisc.edu/niagara/Pu blications.html.

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Je#rey Naughton, David DeWitt, and David Maier et. al. The Niagara internet query system. Submitted for Publication.

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