外文翻译--改进ADO.NET性能.doc

附录1.英文资料ImprovingADO.NETPerformanceImproving.NETApplicationperformanceandscalabilitySummary:Thischapterprovidesprovenstrategiestohelpyoudesignanddevelopscalabledataaccesssolutions.Topicscoveredincludedifferenttechniquestopassdataacrossapplicationlayers,managingthedatabaseconnectionpool,optimizingstoredprocedurecalls,reducingdatasetserializationcost,techniquesforpagingthroughlargeresultsets,managingtransactions,handlingBLOBS,andmuchmore.ObjectivesOptimizeyourdataaccessdesign.ChoosebetweenDataSetsandDataReaders.Runefficientdatabasecommands.Passdatabetweenlayersefficiently.Performefficienttransactions.Optimizeconnectionmanagement.Evaluatethecostofpagingthroughrecords.Evaluatecriteriaforanalyzingdataaccessperformance.Applyperformanceconsiderationstobinarylargeobject(BLOB)manipulation.OverviewWell-designeddataaccesscodeanddataprocessingcommandsareessentialelementsforapplicationperformanceandscalability.Typically,thedatabaseisafocalpointforapplicationloadbecausethemajorityofapplicationrequestsrequiredatathatcomesfromadatabase.Thischapterprovidesprovenstrategiesfordesigningandimplementingdataaccesscodeforperformanceandscalability.HowtoUseThisChapterUsethischaptertoimprovetheimplementationofyourdataaccesscodeforperformanceandscalability.Togetthemostoutofthischapter,considerthefollowing:Jumptotopicsorreadbeginningtoend.Themainheadingsinthischapterhelpyoutoquicklyidentifyandthenlocatethetopicthatinterestsyou.Alternatively,youcanreadthechapterbeginningtoendtogainathoroughappreciationoftheissuesthataffectADO.NETperformance.Usethechecklist.UseChecklist:ADO.NETPerformanceintheChecklistssectionofthisguidetoquicklyviewandevaluatetheguidelinespresentedinthischapter.UsetheArchitecturesectionofthischaptertounderstandhowADO.NETworks.Byunderstandingthearchitecture,youcanmakebetterdesignandimplementationchoices.UnderstandcoreADO.NETcomponents,suchasdataproviderobjectsandtheDataSetobject.UsetheDesignConsiderationssectionofthischaptertounderstandthehigh-leveldecisionsthatwillaffectimplementationchoicesforADO.NETcode.Measureyourapplicationperformance.learnaboutthekeymetricsthatyoucanusetomeasureapplicationperformance.Youhavetomeasureapplicationperformancesothatyoucanidentifyandresolveperformanceissues.Testyourapplicationperformance.Testing.NETApplicationPerformancetolearnhowtoapplyperformancetestingtoyourapplication.Youhavetoapplyacoherenttestingprocessandanalyzetheresults.Tuneyourapplicationperformance.Tuning.NETApplicationPerformancetolearnhowtoresolveperformanceissuesthatyouidentifythroughtheuseoftuningmetrics.TuneSQLServer.ReadChapter14,ImprovingSQLServerPerformancetoensurethatyourMicrosoftSQLServerdatabaseisappropriatelyconfigured.ArchitectureADO.NETreliesondataproviderstoprovideaccesstotheunderlyingdatasource.Eachdataproviderexposesasetofobjectsthatyouusetomanageconnections,retrievedata,andupdatedata.Thecoreobjectsarethefollowing:ConnectionCommandDataReaderDataAdapterInaddition,ADO.NETprovidestheDataSetobject,whichprovidesadisconnectedcacheofdata.TheDataSetobjectdoesnotrequireaspecifictypeofdatasourceandisnottiedtotheunderlyingdatasourcethatthedatawasobtainedfrom.ThebasicADO.NETarchitectureisshowninFigure12.1.Figure12.1:ADO.NETarchitectureThefollowinglistoutlinesthepurposeofeachofthemainADO.NETobjects:Connection.Thisobjectrepresentsaconnectiontoadatabase.Command.ThisobjectrepresentsanSQLstatementthatisrunwhileconnectedtoadatasource.ThisobjectcanbeastoredprocedureoradirectSQLstatement.DataReader.Thisobjectretrievesaread-only,forward-onlystreamofdatafromadatabase.TheDataReaderobjectisdesignedforconnectedscenariosandoffersbetterperformancethanreadingdataintoaDataSetobjectattheexpenseoffunctionality.FormoreinformationabouthowtouseDataReaderobjectsandDataSetobjects,seeDataSetvs.DataReaderlaterinthischapter.DataAdapter.ThisobjectchannelsdatatoandfromaDataSetobjectandt