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1、REX:Recursive,Delta-BasedData-CentricComputation∗SvilenR.MihaylovZacharyG.IvesSudiptoGuhaUniversityofPennsylvaniaPhiladelphia,PA,USA{svilen,zives,sudipto}@cis.upenn.eduABSTRACTqueriesforrelationshipanalysis,entityresolution,clustering,andrecommendation.Thishasspu
2、rredthedevelopmentofanewgen-Intoday’sWebandsocialnetworkenvironments,queryworkloadserationofscalable“NoSQL”clusterdataprocessingplatformsthatincludeadhocandOLAPqueries,aswellasiterativealgorithmsanalyzedataoutsidetheDBMS.ExamplesincludeGoogle’sMap-thatanalyzedata
3、relationships(e.g.,linkanalysis,clustering,learn-Reduce[8]anditsopen-sourceHadoopalternative,Pregel[20],ing).ModernDBMSssupportadhocandOLAPqueries,butmostDryad[16]andPig[21].Suchplatformsareoftentargetedatlarge-arenotrobustenoughtoscaletolargeclusters.Conversely,
4、“cloud”scale“cloudcomputing”tasks,hencewerefertothemascloudplatformslikeMapReduceexecutechainsofbatchtasksacrossplatforms,eventhoughtheycanbetargetedattraditionalclusters.clustersinafaulttolerantway,buthavetoomuchoverheadtosup-Thesecloudplatformssharemanyimplemen
5、tationtechniquesportadhocqueries.withparallelDBMSs,yettheymakedifferenttrade-offsthatyieldMoreover,bothclassesofplatformincursignificantoverheadinseveralbenefits:scale-uptomany(possiblyheterogeneous)nodes,executingiterativedataanalysisalgorithms.Mostsuchiterativeea
6、sierintegrationwithuser-definedcodetosupportspecializedal-algorithmsrepeatedlyrefineportionsoftheiranswers,untilsomegorithms,andtransparenthandlingoffailures(whichfrequentlyconvergencecriterionisreached.However,generalcloudplatformsoccurinlargeclusters).Ontheotherh
7、and,mostplatformssacri-typicallymustreprocessalldataineachstep.DBMSsthatsupportficeoneormoreof:high-levelprogrammingabstractions,prede-recursiveSQLaremoreefficientinthattheypropagateonlythefinedprimitiveslikejoins,ordeclarativeoptimizationtechniques.changesineachste
8、p—buttheystillaccumulateeachiteration’sMoreover,theseplatformstendtobemostusefulforbatchjobs,state,evenifitisnolongeruseful.User-definedfunctionsarealsoandsomea
