On boosting holism in XML twig pattern matching using structural indexing techniques .pdf

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1、OnBoostingHolisminXMLTwigPatternMatchingUsingStructuralIndexingTechniquesTingChen,JiahengLuandTokWangLingSchoolofComputingNationalUniversityofSingapore3ScienceDrive2,Singapore117543{chent,lujiahen,lingtw}@comp.nus.edu.sgABSTRACTwhichcanbeeitherparent-childorancestor-descendantre-lationshi

2、ps.Afterthat,eachbinaryrelationshipisprocessedSearchingforalloccurrencesofatwigpatterninanXMLusingstructuraljointechniques[1][20]andthefinalmatchdocumentisanimportantoperationinXMLqueryprocess-resultsareobtainedby“stitching”individualbinaryjoinre-ing.RecentlyaholisticmethodTwigStack[2]hasb

3、eensultstogether.Themainproblemwiththeabovesolutionisproposed.Themethodavoidsgeneratinglargeinterme-thatitmaygeneratelargeandpossiblyunnecessaryinter-diateresultswhichdonotcontributetothefinalanswermediateresultsbecausethejoinresultsofindividualbinaryandisCPUandI/Ooptimalwhentwigpatternson

4、lyhaverelationshipsmaynotappearinthefinalresults.ancestor-descendantrelationships.Anotherimportantdi-Brunoetal.[2]proposesanovelholisticXMLpathandrectionofXMLqueryprocessingistobuildstructuralin-twigpatternmatchingmethodTwigStackwhichavoidsstor-dexes[3][8][13][15]overXMLdocumentstoavoidunn

5、eces-ingintermediateresultsunlesstheycontributetothefi-saryscanningofsourcedocuments.WeregardXMLstruc-nalresults.Themethod,unlikethedecompositionbasedturalindexingasatechniquetopartitionXMLdocumentsmethod,avoidscomputinglargeredundantintermediatere-andcallitstreamingschemeinourpaper.Inthis

6、paperwesults.ThemethodisCPUandI/Ooptimalforallpath(withdevelopamethodtoperformholistictwigpatternmatch-nobranch)patternsandtwigpatternswhoseedgesareen-ingonXMLdocumentspartitionedusingvariousstreamingtirelyancestor-descendantedges.Meanwhilethespacecom-schemes.Ourmethodavoidsunnecessarysca

7、nningofirrel-plexityoftheiralgorithmisboundedbythelongestpathinevantportionofXMLdocuments.Moreimportantly,de-thesourceXMLdocument.Howevertheapproachisfoundpendingondifferentstreamingschemesused,itcanprocesstobesuboptimalifthereareparent-childrelationshipsinalargeclas