English  |  正體中文  |  简体中文  |  Post-Print筆數 : 27 |  Items with full text/Total items : 95844/126434 (76%)
Visitors : 31567409      Online Users : 415
RC Version 6.0 © Powered By DSPACE, MIT. Enhanced by NTU Library IR team.
Scope Tips:
  • please add "double quotation mark" for query phrases to get precise results
  • please goto advance search for comprehansive author search
  • Adv. Search
    HomeLoginUploadHelpAboutAdminister Goto mobile version
    政大機構典藏 > 理學院 > 資訊科學系 > 期刊論文 >  Item 140.119/69370
    Please use this identifier to cite or link to this item: http://nccur.lib.nccu.edu.tw/handle/140.119/69370

    Title: A Localized Approach to Query Optimization in Heterogeneous Database System
    Authors: 陳良弼
    Tsai,Pauray S. M.;Chen,Arbee L. P.
    Contributors: 資科系
    Keywords: heterogeneous databases;localized query processing;entity join;neighborhood join;constraint relaxation
    Date: 1993-12
    Issue Date: 2014-08-28 10:08:18 (UTC+8)
    Abstract: Heterogeneities exist in multiple databases. For example, a real world entity may be differently represented in relations of different databases. In particular, keys of these relations may be incompatible. In this paper, we develop an entity join operator named EJ operator, which can be used to join two relations on their compatible/incompatible keys. By using this join, if an entity is represented in both relations, all its properties given in relations can be obtained. Furthermore, a neighborhood join operator named NJ operator is introduced, which joins relations allowing some degree of value uncertainty on the join attributes. The EJ operator, NJ operator and the previously proposed extended relational operators can be combined to support a more powerful set of operations on heterogeneous databases. Since the EJ operator "integrates" tuples from relations, whose attribute values may have conflicts, a natural way to process the operator is to transmit both relations to a site, resolve the conflicts and process the join, which is very costly. An approach which transforms a global query into local subqueries to process queries with EJs in multiple sites is, thus, proposed in an attempt to lower the query processing cost.
    Relation: Journal of Inforamtion Science and Engineering,9(4),605-623
    Data Type: article
    Appears in Collections:[資訊科學系] 期刊論文

    Files in This Item:

    File Description SizeFormat

    All items in 政大典藏 are protected by copyright, with all rights reserved.

    社群 sharing

    DSpace Software Copyright © 2002-2004  MIT &  Hewlett-Packard  /   Enhanced by   NTU Library IR team Copyright ©   - Feedback