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1、Chapter20:DataAnalysisChapter20:DataAnalysisDecisionSupportSystemsDataWarehousingDataMiningClassificationAssociationRulesClusteringDecisionSupportSystemsDecision-supportsystemsareusedtomakebusinessdecisions,oftenbasedondatacollectedbyon-linetransaction-processingsystems.Examplesofbusinessdec
2、isions:Whatitemstostock?Whatinsurancepremiumtochange?Towhomtosendadvertisements?ExamplesofdatausedformakingdecisionsRetailsalestransactiondetailsCustomerprofiles(income,age,gender,etc.)Decision-SupportSystems:OverviewDataanalysistasksaresimplifiedbyspecializedtoolsandSQLextensionsExampletask
3、sForeachproductcategoryandeachregion,whatwerethetotalsalesinthelastquarterandhowdotheycomparewiththesamequarterlastyearAsabove,foreachproductcategoryandeachcustomercategoryStatisticalanalysispackages(e.g.,:S++)canbeinterfacedwithdatabasesStatisticalanalysisisalargefield,butnotcoveredhereData
4、miningseekstodiscoverknowledgeautomaticallyintheformofstatisticalrulesandpatternsfromlargedatabases.Adatawarehousearchivesinformationgatheredfrommultiplesources,andstoresitunderaunifiedschema,atasinglesite.Importantforlargebusinessesthatgeneratedatafrommultipledivisions,possiblyatmultiplesit
5、esDatamayalsobepurchasedexternallyDataWarehousingDatasourcesoftenstoreonlycurrentdata,nothistoricaldataCorporatedecisionmakingrequiresaunifiedviewofallorganizationaldata,includinghistoricaldataAdatawarehouseisarepository(archive)ofinformationgatheredfrommultiplesources,storedunderaunifiedsch
6、ema,atasinglesiteGreatlysimplifiesquerying,permitsstudyofhistoricaltrendsShiftsdecisionsupportqueryloadawayfromtransactionprocessingsystemsDataWarehousingDesignIssuesWhenandhowtogatherdataSourcedrivenarchitecture:datasourcestransmitnewinformationtowarehouse,eithercontinuouslyorperiodically(e
7、.g.,atnight)Destinationdrivenarchitecture:warehouseperiodicallyrequestsnewinformationfromdatasourcesKeepingwarehouseexactlysynchronizedwithdatasources(e.g.,usingtwo-phasecommit)istooexpensiveUsuallyOKtohaveslightlyout-of-datedataatwarehouseData/upd