1366 1365 1357 1364 1363 1362 1358 1355 1356 1361 1360 1359 TKesetecKniquesZereaOsousedintKeBMSmartAnaOticsOptimierforDB2forOSV11apredecessorproducttotoda ID: 263579
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1366 1365 1357 1364 1363 1362 1358 1355 1356 1361 1360 1359 coOumnstKatareusedOaterintKequer\.COearO\tKeseau[iOiar\coOumnsintKepa\OoadZiOOconsumeOessspaceintKeKasKtabOeZKentKe\tooareretainedinencodedform.EventKeresuOtsofe[pressionsma\benefitfromencodinJdata³ontKeÀ\´i.e.b\re-encodinJtKeresuOtsofe[pressionsastKe\areevaOuated.1.1ContributionsTKispaperdescribesKoZMoinsareprocessedonencodeddataintKe,nformi[:areKouseAcceOerator,:Aamain-memor\acceO-eratortotKedisN-based,nformi[databaseserverproductpacNaJedtoJetKerastKe,nformi[UOtimate:areKouseEdition,U:E.,:AreadsseOectedroZ-orJani]eddatatKatisstoredondisNb\tKe,nformi[databaseserverencodeseacKcoOumnindependentO\andstorestKatdataintKememor\of,:AusinJaPA;-OiNepaJeformat>2].Aquer\posedto,nformi[isautomaticaOO\routedto,:AiftKedatareferencedintKatquer\isrepOicatedin,:AotK-erZisetKe,nformi[dataservere[ecutesontKeoriJinaOdata.See>3]foranovervieZoftKe,:As\stem.DurinJquer\processinJMoinsareperformedontKeencodedcoOumnsZitKoutKavinJtoKaveacommondictionar\betZeentKosecoOumns.,nsteadZetranslatetKeencodedvaOueofonecoO-umntotKeencodedvaOueoftKeotKerbeforeZescantKesecondtabOe.MoreovertKistransOationsupportsami[ofcompressedanduncompressedvaOuesZitKinacoOumn.TKisapproacKprovidesusZitKbettercompressionandmoreÀe[ibOereorJani]ationastKedataisincrementaOO\updatedZKiOestiOOe[ecutinJtKeMoinZitKe[ceOOentperformance.SpecificaOO\tKecontributionsoftKispaperincOude1.:eMustif\tKebenefitofperforminJMoinsonencodedcoOumns.2.:eintroduceanoveO³on-tKe-À\´encodinJscKemeforpayloadcoOumnsusinJaneZKasKtabOedatastructuretKatassiJnssta-bOebucNetpositionstoinsertedvaOues.3.:ee[pOoretKeprobOemofaddinJvaOuesnotfoundintKeoriJi-naOdictionar\andtKebenefitofpartitioninJtKedomaintodeaOZitKtKisprobOem.4.:edescribeatecKniqueforperforminJKasKMoinsonencodedcoOumnseacKofZKicKma\KaveitsoZndictionar\.FortKispurposeZeproposeanotionofencodingtranslationandde-veOoptZovariantseagerdeferredtransOations.5.:econducte[tensivee[perimentsusinJ,:AontKeTPC-+datasettodemonstratetKeadvantaJesofourapproacK.,:AKasbeenJeneraOO\avaiOabOesinceMarcK2011ontKe/inu[operatinJs\stemon,nteOprocessor-basedserverstKe,BMA,;operatinJs\stemon,BMPO:ERprocessor-basedserverstKe+P-U;operatinJs\stemon,nteO,taniumprocessor-basedserversandtKeOracOeSoOarisoperatinJs\stemonOracOeSPARCservers.:KenrunninJon/inu[tKedatabaseserverandtKeacceOeratorcanbeinstaOOedontKesameordifferentcomputerscommunicat-inJviaTCP/,P.DurinJquer\processinJeacKquer\ise[ecutedinparaOOeOb\ZorNerprocesseson,:AandmerJedandreturnedto,nformi[b\acoordinatorprocess.:KenbotK,nformi[and,:AarerunninJontKesamemacKinetKecoordinatorandZorNernodessimpO\becomeprocessesontKesamemacKinetKatcommunicateviaOoopbacN.,nformi[and,:AcanbeondistinctSMPKardZareZitK,:ArunninJbotKtKecoordinatorandZorNerprocessesontKesameKardZare.,:AcanaOsobedepOo\edonabOadeserverforincreasedcapacit\andperformancesucKas,nteO;eon-based,BMserverssupportinJupto0coresand6TBofDRAM.Nodes TKesetecKniquesZereaOsousedintKe,BMSmartAnaO\ticsOp-timi]erforDB2for]/OSV1.1apredecessorproducttotoda\¶s,BMDB2AnaO\ticsAcceOeratorforDB2for]/OS.on,BMbOadeserverssupportupto4socNetsandupto640*BofDRAM.SincebotKtKenumberofcoresandmemor\capacit\oftKeKardZareisincreasinJrapidO\tKe,U:EsoftZareKasbeenpacNaJedÀe[ibO\enouJKtorundirectO\onKardZareorinavir-tuaOi]ed/cOoudenvironment.EacKdatabaseservercanKave]erooneormore,:AsattacKedtoit.1.2OutOineTKerestoftKispaperisorJani]edasfoOOoZs.Section2e[pOainstKebasicsofKasKMoins.Sections3and4tKenJointoencodinJforMoincoOumnsandpa\OoadcoOumnsrespectiveO\.Sections5and6presentourapproacKofpartitioninJaMoincoOumnandtZovariantsofencodinJtransOation.,nSectionZepresenttKeresuOtsandanaO\sisofoure[periments.:esurve\reOatedZorNinSectionandconcOudeinSection.2.JO,NS,:AusesKasKMoinsasitsprimar\MoinmetKod.AKasKMoiniscomposedofabuildphaseandaprobephase.BeOoZZedescribetKeKiJK-OeveOprocedureofMoininJoneormorebuiOdtabOesZitKoneprobetabOe.DurinJtKebuiOdpKaseoneormoretabOesareeacKscannedappO\inJpredicatesOocaOtotKattabOe.QuaOif\inJroZsaddtKeirMoin-coOumnvaOuestoaKasKtabOefortKattabOe.OptionaOO\loadcolumnstKatZiOObeusedOaterintKequer\ma\aOsobein-sertedintotKesamebucNetoftKeKasKtabOeZitKitsMoin-coOumnvaOues.TKisprocedureisrepeatedforeacKbuiOdtabOetoZKicKtKeprobetabOeisMoined.DurinJtKeprobepKasetKeprobetabOeisscannedappO\inJan\predicatesOocaOtotKattabOeandtKenevaOuatinJeacKMoinpred-icateb\probinJtKecorrespondinJKasKtabOetKatZasbuiOtforeacKbuiOdtabOetocKecNifeacKMoin-coOumnvaOuee[ists.,fitdoestKepa\OoadcoOumnsZiOObefetcKedfromtKeKasKtabOetodosubsequentJroupinJandaJJreJation.AOtKouJKtKeencodinJandpartitioninJtecKniquespresentedintKispaperareappOicabOeJeneraOO\itisconvenientandcOearertopresentourencodedMointecKniqueusinJtKeterminoOoJ\ofschemascommoninO/APs\stems>16]inZKicKoneormoredimensiontablesactastKebuiOdtabOestobeMoinedZitKaver\OarJefacttableastKeprobetabOe.SimiOarO\tKetecKniquesoftKispaperarenotOimitedtoMoinsbetZeenprimarykey(PK)foreignkey(FK)coOumnsaOtKouJKZeZiOOfinditcOearertoreferencetKeMoincoOumnstKatZa\.E[ampOeFiJure1sKoZsane[ampOeofprocessinJasimpOeMoinquer\betZeen./ocaOpredicatesarespecifiedonandJroupinJisdoneb\tKevaOuesof.TKustKeKasKtabOefromcontainstKevaOuesoftKeP.coOumntKepa\OoadcoOumnoftKequaOif\inJroZs.TKisKasKtabOeispassedtotKefact-tabOescan.akeschemasKavinJmoretKanoneOeveOofdimensiontabOestKistecKniquema\beappOiedrecursiveO\startinJfromtKeoutermostdimensiontabOesandMoininJinZard.,nsucKcasesatabOeZKicKisneitKerouter-mostnorinner-mostintKescKemaactsasbotKafacttabOeandadimensiontabOeinsuccessiveMoins.3.ENCOD,N*JO,NCO/UMNSPastZorNonMoinprocessinJovercompresseddataeitKerfo-cusedonnestedOoopMoins>1]ZKicKarenotsuitabOeforbusi-nessinteOOiJenceB,queriesorusedsimpOeapproacKessucKasencodinJbotKMoinsidesine[actO\tKesameZa\ZKicKsacrifice scanORDERS O_OrderDate… scan/,NE,TEM /_SKipDate… /_Order.e\,N … /ooN up tKe vaOues of *roup b\ AJJreJation O_Order.e\O_OrderDate DimensionFact +asK TabOe FiJure1E[ampOeofstar-MoinprocessinJ.compressionperformance>].,ntKissectionZeZiOOdeOvemoredeepO\intoperforminJKasKMoinsoncompressedvaOuese[pOor-inJbotKtKeadvantaJesandcKaOOenJesasZeOOaspracticaOtecK-niquesfordeaOinJZitKunencodedvaOuesanddifferentcompres-sionscKemesbetZeentKedifferentMoincoOumns.3.1:K\JoinonCompressedVaOues?SinceMoinsconsumetKebuONofquer\processinJtimeinmostB,queriesitseemsaOmostobvioustKatNeepinJvaOuescompressedZKiOeperforminJMoinsZiOOsiJnificantO\improvequer\perfor-mance.B\occup\inJOessspacecompressedvaOuesconsumefeZerresourcessucKasspaceinKasKtabOestKereb\reducinJcacKe-Oinemisses.TKisappOiestobotKMoincoOumnsasZeOOaspayloadcolumns.:eZiOOaddresstKesetZot\pesofcoOumnssep-arateO\.AdditionaOO\NeepinJvaOuesKiJKO\compressedpermitspacNinJmuOtipOevaOuesintoareJisterandcomparinJtKemZitKasinJOeinstructionacKievinJincreasedparaOOeOismtKrouJKsinJOeinstructionmuOtipOedataSIMDoperationssucKasvaOuecompar-isons>1].3.2T\pesofCompressionCoOumnsin,:Aarecompressedb\oneofafeZencodinJscKemes.Dictionar\encodinJinZKicKeacKvaOueisrepOacedb\itscodeisusedforcoOumnsZitKOoZcardinaOit\andatOeastsomerepetitionsandpreferabO\somesNeZintKoserepetitionssucKasF.coOumns.CoOumnsKavinJnorepetitionssucKasaP.coOumnZiOOJainnotKinJfromdictionar\encodinJandareusuaOO\com-pressedZitKminusencodingZKicKstorestKedifferenceofavaOuefromaJivenentr\intKedictionar\.ForstrinJfieOdsZeuseavari-anttKatappOies;ORinsteadofdifferencecaOOedprexencodingMinusencodinJstiOOrequiresadictionar\ZitKatOeastoneeOement.Fore[ampOetKevaOuesandcanbemorecompactO\representedinMust4bitsastKedifferencesfromasinJOedictionar\vaOue.Prefi[encodinJremovesacommonOeadinJportionandZorNsZeOOonUR/sinte-JersZitKOeadinJ]erosorotKerappOication-specificcommonaOit\sucKasµCUST0004¶µCUST004¶µCUST0101¶etc.:econsideredbutdiscardedman\otKercompressionmetKods.Run-OenJtKencodinJR/EcountstKenumberofsuccessivevaOuestKatareidenticaOsoismosteffectiveZKeninstancesareorderedasinC-Store¶sproMections>20].Abadi¶s³NuOOCompression´>1]isaspeciaOcaseofR/E.Bit-vectorencodinJiseffectiveonO\fore[tremeO\OoZ-cardinaOit\coOumns./empeO-=iv/=compressionZorNsonO\ZKenroZsneednotbeaccessedindividuaOO\e.J.forcompressinJentirepaJes.3.3MatcKinJEncodedVaOuesTKeencodinJscKemesdescribedaboveassiJnauniquecodetoeacKencodedvaOue.TKusZecanappO\tKeMoinpredicateoncodesinsteadofonvaOues.ButtKeMoincoOumnsonbotKsidesoftKeMoinmustbeencodedidenticaOO\.TKebasicideaforperforminJMoinsonencodedvaOuesisquitesimpOeiftKesamecompressionmappinJisappOiedtotZovaOuestKatareequaOtKentKeirencodedvaOuesareequaO.:KentKemappinJisanisomorpKismtKentKeconverseisaOsotrue.TKatisiftKeencodedvaOuesareequaOtKentKeunencodedvaOuesareequaOTKerearetKreeoptionsforreaOi]inJtKisidenticaOencodinJEncodinJMoincoOumnsidenticaOO\ondisNper-domainen-codinJ,tseemsnaturaOtKattZovaOuesbeinJtestedforequaOit\ZKicKaredraZnfromdifferentcoOumnssKouOdbeencodedZitKtKesamemappinJ.AbadietaO.>1]andman\previousautKorsKaveassumedtKissimpOeper-domainencod-ing.,denticaOO\encodinJbotKcoOumnstobeMoinedisideaOforMoinspeedbecausetKetZocoOumnscanbecompareddirectO\.ButZefoundtKisapproacKtobeunZorNabOe.FirstofaOOZouOdZeNnoZaprioiaOOtKecoOumnsauserZouOdMoinon?DBAsdoKaveabestpracticeofspecif\inJreferentiaOin-teJrit\R,asconstraintsorasKints.Sa\tKatZeKaveR,sfromtKecoOumnsofata-bOetoadimension.TKeR,saresuJJestiveofaMoinbutZKicKcoOumn¶sdistributionsKouOdZepicNforderivinJtKecommonencodinJ?TKe³Kub´oftKeR,sZiOObeaprimar\Ne\effectiveO\maNinJaOOtKecodesfi[edOenJtKsincetKeNe\OiNeO\Kasauniformdistribution.Section5.2describesman\reasonsZK\,:AusesvariabOeencodinJOenJtKs.TransOatinJbotKMoincoOumnstoaneZcommonencodinJatruntimeTKisistKemostÀe[ibOeoptionbecauseZecancKooseanencodinJtKatisbestfortKesubsetofvaOuestKatac-tuaOO\participateintKeMoinpotentiaOO\compressinJevenbet-tertKantKeoriJinaOencodinJoftKosecoOumns.ButZedopa\fortKeCPUcostofdecodinJandre-encodinJvaOuesonbotKcoOumns.FornumericaOcoOumnsZeusuaOO\empOo\minusen-codinJanditisfairO\cKeaptodecodeandre-encodesinceZedonotneedtoaccesstKedictionar\forever\sinJOecodeZearedecodinJ.:itKdictionar\encodinJdecodeinvoOvesarandomaccessandre-encodeinvoOvesaKasKtabOeOooNupsoarequitee[pensivetodoonbotKsidesoftKeMoin.EncodinJMoincoOumnsindependentO\andtransOatinJoneMoincoOumntotKeencodinJoftKeotKeratruntimeper-coOumnencodinJAspartofMoinprocessinJZecanunif\tKeencodinJoftKeMoincoOumns.,naKasKMoinZecaneitKerconverttKebuiOdsidetotKeencodinJusedintKeprobesideorvice-versa.:ecKosetKisoptionfor,:AZKicKenabOesustoindependentO\encodecoOumnsbecausetKevaOuespresentineacKcoOumnaret\picaOO\ver\differenteventKouJKtKe\aredraZnfromtKesamedomain.:ecaOOtKisper-columnencod-ing.TKedoZnsidetoper-coOumnencodinJistKatZemustper-formencodingtranslation.,n,:AZetransOatefromtKeen-codinJoftKebuiOdsidetotKeencodinJoftKeprobesideZKicKJivesreducedtransOationcostfortKeusuaOcaseZKeretKebuiOdsideissmaOOer.TransOationisformaOO\definedinDefinition1i.e.)==DefinitionConsidertZoencodedvaOuesfromdifferentcoOumnscompressedZitKtKemap-pinJsrespectiveO\.denotesde-compressionusinJtKemappinJ.Encodingtranslationisperf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detaiOKoZeverZefirstintroduce³on-tKe-À\´encodinJofpa\-OoadcoOumnsandtKeneedforpartitioninJeacKcoOumn¶sdomain.4.ENCOD,N*PAY/OADDATAON-T+E-F/YENCOD,N*NeedforOn-tKe-FO\EncodinJOurfocussofarKasbeenonencodinJofMoincoOumns.ButZKatabouttKepayloadcolumnsZKicKaretKecoOumnsusedOaterintKequer\sucKasforJroupinJ?TKepa\OoadofaMoint\picaOO\KascoOumnsfromtKedimensiontabOestKatareusedinJroupinJ.Fore[ampOeaquer\tofindtKeaveraJeorderpriceJroupedb\tKecustomercit\andtKeproductbrandZiOOpicNtKosecoOumnsfromMoinsZitKtKedimensions.TKeMoinNe\isusuaOO\MustaninteJerZKereastKepa\OoadsareoftenZiderstrinJs..eepinJtKemcompressedreducestKesi]eoftKeKasKtabOeforbotKMoinandJroup-b\onO\afterappO\inJtKe+AV,N*predicatesZeneedtodecompresstKem.TKeoriJinaOencodinJofapa\OoadcoOumnisinsufficienttoacKievetKisJoaOfortKereasonsOistedbeOoZ.TKus,:AencodestKepa\OoadvaOueson-the-OTFUpdates,tisunreaOistictoassumetKataOOvaOuesZiOObeen-codabOeZitKafi[eddictionar\.OvertimeneZvaOuesforacoO-umnJetinsertedandtKe\ZiOObestoredunencoded.SoeacKpa\OoadcoOumnKasatOeasttZorepresentations²encodedandunencoded²andpotentiaOO\moreiftKedistributionKassNeZ.ButKasKtabOedatastructuresdonotdirectO\KandOevariabOe-OenJtKpa\Ooads.SoZeeitKerKavetopadtKemaOOtounen-codedvaOuesorKavedifferentKasKtabOesZKereistKenumberofpa\OoadcoOumns.TKisissuearisesfortKeMoinNe\stoobutitiseasiertoKandOesinceissmaOOoften1.E[pressionsOTFencodinJcanbeappOiednotMusttocoOumnsbutaOsoe[pressions.Fore[ampOeJroupinJisoftenper-formedonacoarsifiedformofadimensioncoOumnsucKas.NormaOO\tKise[pressionresuOtZouOdbeOeftunencodedbutZitKOTFencodinJZecane[pOoittKesmaOOcardinaOit\ofmontKsandencodeitver\compactO\.CorreOationOTFencodinJcanaOsoe[pOoitcorreOations.,tiscommontoJrouponcorreOatedcoOumnssucKasand.DurinJOoadtKesecoOumnsZiOObeencodedindividuaOO\.Butatquer\timeZecane[pOoittKecorreOationamonJtKemtoproduceatiJKtercode.Predicates/ocaOand/orMoinpredicatesZiOOOiNeO\reducetKecardinaOit\ofeacKcoOumnaOOoZinJamorecompactrepresen-tationinareduceddictionar\.Fore[ampOepredicatesontKemontKand\earZouOdOiNeO\reducetKecardinaOit\ofaOOre-maininJdatecoOumnsb\anorderofmaJnitudeormore.OTFMappinJTabOeZitKStabOe+asKPositionsOTFencodinJisamappinJfromavaOuetoafi[ed-OenJtKcodeandZeneedtoconstructtKismappinJinasinglepassovertKeinputi.e.aspartoftKeoperatorpipeOinefortKebuiOdsideoftKeMoin.,:AusesanoveOOTFmappingtabletoconstructtKismap-pinJ.AsZeencounterunencodedvaOuestKe\areinsertedintotKismappinJtabOe.,faneZvaOueonenotseenuntiOtKenisen-counteredaninsertcaOOaddsittotKemappinJtabOeandoutputsanOTFcodeZKicKisactuaOO\anindexintotKebucNetZKeretKevaOueZasinserted.,fane[istinJvaOueisencounteredaninsertcaOOreturnstKeinde[oftKee[istinJvaOue. :edidnotuseapointertoaKeapobMectbecausetKatcostsan-otKerpointerasZeOOasmorefraJmentationintKememor\pooOandincursOatcKcontentionintKememor\aOOocator.:ecannotimpOementtKismappinJtabOeasastraiJKtKasKtabOebecausetKeOTFcodeassiJnedtoavaOuecanneverbecKanJedevenifthehashtableisresized.SotKeOTFmappinJtabOeisim-pOementedasaOistofKasKtabOeseacKdoubOetKecapacit\oftKeprevious.EacKKasKtabOeisastandardOinearprobinJKasKtabOeKoOdinJtKeunencodedvaOues.TKeOTFcodeassiJnedtoavaOueiscaOcuOatedfromtKeKasKbucNetitfaOOsintocumuOativeO\addinJtKecapacit\ofaOOearOierKasKtabOesandtKesi]eoftKeoriJinaOdictionar\itseOf.E[ampOeConsideramappinJtabOemadeupoftKreeKasKtabOesofcapacit\1024204and406entries.SupposetKattKeoriJinaOdictionar\Kas600entries.TKenavaOuetKatJoesintotKebucNet40intKetKirdKasKtabOeZiOOJetanOTFcode600+1024+2048+40=3712TKeKasKtabOesZitKintKemappinJtabOeareimpOementedasOocN-freedatastructures.TKeOistofKasKtabOesisaOocN-freearra\ofpointersandconcurrentinsertstotKeKasKtabOesusecompare-and-sZaponÀaJsoneÀaJperbucNetfors\ncKroni]ation.CompactionoftKeOTFCodeTKisOTFcodeisinitiaOO\si]edtotKeoftKema[imumnum-berofunencodedvaOuesZemiJKtencounter.,:AmaintainstKisupperboundasunencodedvaOuesareinserted.ForOTFencodinJovere[pressionsZeusea64-bitnumber.AftertKebuiOdsideoftKeMoinKasbeenfuOO\scannedandaOOpossibOeunencodedvaOuesKavebeenseenZeNnoZe[actO\KoZZidetKeOTFcodeneedstobe.SoZecanrevisittKevaOuesand³compact´tKeOTFcodesfurtKer.DB2ZitKB/UacceOeration>1]aOsoempOo\sOTFencodinJ.+eretKebuiOdsideofKasKMoinsusespartitioninJsoZeKaveanopportunit\aftertKeinputKasbeenpartitionedtodotKiscom-pactionaspartofenterinJtKepa\OoadsintotKeMoinKasKtabOeitseOf.EacKOTFKasKtabOeisMustabitmaptKereisnopa\OoadsotKiscompactionrequiresonO\asimpOeOinearscanoftKebitmaptocomputeaprefi[popuOationcountforeacKoccupiedbucNetandtKenascanovertKepartitionZitKOooNupintotKeOTFKasKtabOetoreassiJnOTFcodes.Performance,mprovementb\OTFEncodinJToinvestiJatetKeimpactoftKeOTFencodinJonquer\perfor-manceZeranqueriesobtainedfromreaOcustomerZorNOoadstKatreferencebotKMoinandpa\OoadcoOumns.TKequeriesZeree[e-cutedZitKtKeOTFencodinJenabOedanddisabOedrespectiveO\ona100*BTPC-DSdataset.FiJure2sKoZstKatOTFencodinJimprovedtKeperformanceofaOOqueries²b\1%onaveraJeandupto52%. FiJure2,mpactoftKeOTFencodinJ.5.PART,T,ON,N*CO/UMNDOMA,NSTKissectiondescribesZK\andKoZ,:ApartitionsdatabeforeencodinJandstorinJit. 5.1ProbOemofUncompressedVaOuesAn\compressionscKemeusinJadictionar\KasafundamentaOcKaOOenJeKoZtodeaOZitKneZvaOuesnotpresentZKentKedic-tionar\Zascreated.TZocommonsoOutionsare/eaveRoomOnecommonapproacKtodeaOinJZitKneZvaO-uesistoOeavesufficientroomintKeinitiaOdictionar\forfuturevaOues.+oZevertKisKasanumberofprobOemsassociatedZitKit.+oZmucKspaceisenouJK?OverestimatinJtKenumberoffuturevaOuesmeanstKatbitcombinationsZiOObeZasted.Fore[ampOedoubOinJtKedictionar\si]efromvaOuestovaOuesaddsonebittoaOOvaOuesZKicKZouOdaOZa\sbe0forvaOuesintKeinitiaOdictionar\andZouOdbeunnecessar\ifnoneZvaOueseveroccurred.ConverseO\oncevaOuesKavebeenaddedtKereisnoZa\toaddadditionaOvaOuesZitKoutre-encodinJever\vaOue.FurtKermoreiftKeinitiaOdictionar\isdefinedtobeorder-preservinJsotKatranJepredicatescanbeappOiedtocompressedvaOues>]tKenaddinJneZvaOuesaftertKeinitiaOvaOuesdestro\stKisorder-preservinJpropert\astKere¶susuaOO\noassurancetKatvaOuesZiOObeaddedtotKedatabaseinan\particuOarordernoran\Za\topredictZKereneZvaOuesZiOOoccur.PartitiontKeEncodedDomainAsecondapproacKtodeaOinJZitKneZvaOuesistopartitiontKedomainandcreateseparatedictionariesforeacKpartition.,ntKisZa\tKeimpactofaddinJneZvaOuescanbeisoOatedfromtKedictionar\sofan\e[-istinJpartitions.TKeinitiaOdictionar\forapartitioncanbeoptimi]edfortKevaOuespresentattKetimeofitscre-ationandneZvaOuescansimpO\beaddedtoapartitionusinJacompOeteO\separatedictionar\tKatZiOObecreatedontKeÀ\asvaOuesarrive.TKecKaracteristicsoftKetZodic-tionariesandtKustKeencodinJscKemescanbecompOeteO\differentaOOoZinJtKecompressionofan\domaintoadapttotKecKaracteristicsoftKeneZvaOues.Fore[ampOecouOdusedictionar\encodinJanddeOtaencodinJ.PartitioninJaOsoisoOatesandOimitstKeimpactofcKanJinJtKecompressionscKeme.Fore[ampOesincetKevaOuesaddedtoarrivedinnoparticuOarorderatsomepointe.J.ZKenitisfuOOZemiJKtZanttore-assiJntKevaOuesindictionar\tomaNeitorder-preservinJ.DoinJsoZouOdaffectonO\tKevaOuesstoredin.AOternativeO\ZecouOdOeavetKevaOuesintKesecondpar-titionunencodedtoavoidtKecostofencodinJtKemtZice²onceZKentKe\arrivedandasecondtimeZKentKepartitionKasfiOOed.TKisunencodedpartitionZouOdofcourseKavetobeprocesseddifferentO\tKantKeencodedpartitionsincreasinJcodecompOe[it\.:eZiOOdiscusstKist\peofpartitioninJmoreinsubsequentsections.NotetKatpartitioninJadomainisver\differentfrombOocN-orpaJe-basedcompressionZKicKmereO\compressesZKatevervaOuesKappentooccurZitKinapK\sicaOcKunN.UnOiNebOocNcompressiondomainpartitioninJb\constructionJuaranteestKataparticuOarvaOuecanoccurinatmostonedictionar\ZKicKcansiJnificantO\simpOif\searcKinJforasinJOevaOue.5.2BetterCompressionAOtKouJKprovidinJaKomeforneZvaOuesisourprimar\rea-sonforpartitioninJtKedomainofeacKcoOumntKerecanbeotKerbenefitstodomainpartitioninJmostnotabO\bettercompression.RamanetaO.>1]describedadomainpartitioninJscKemecaOOedfrequencypartitioningtKate[pOoitssNeZinadomaintoencodemorefrequentvaOuesinfeZerbitsandOessfrequentvaOuesinmorebitsasin+uffmanencodinJZKiOestiOOdefininJandoperatinJonxed-lengthwithineacKpartition.Frequenc\partitioninJisautomaticaOO\doneb\,:AZitKoutinterventionoftKeDBA.E[ampOeConsiderafacttabOeoftKesaOesofproductsKav-inJvariouscountriesoforiJininFiJure3.AtOoadtimeforeacKcoOumnfrequenc\partitioninJindependentO\buiOdsaKistoJramoftKevaOueoccurrencesandpartitionstKeKistoJramintocoOumnpartitionsaccordinJtotKefrequenciesoftKoseoccurrences.TKentKevaOuesineacKpartitionareencodedusinJtKesamenumberofbits.,ntKecoOumnCKinaandtKeUSAaretKemostfre-quentandneedonO\onebittorepresenttKem.TKeEuropeanUnioncountriesarene[tmostfrequentandarerepresentabOeusinJ5bits.TKeremaininJ16orsonationsZouOdrequirebits.,ftKereZere1000000saOesoriJinatinJfromCKinaandtKeUSA100000fromtKeEUcountriesand10000fromotKersaOOvaOuescouOdberepresentedb\onO\000+5000+8000=Mbitsover5.6timesbettercompressiontKantKe.Mbitsrequiredifever\nationZasrepresentedb\eiJKtbitsneededtoen-codeaOOpossibOenations.SimiOarO\ZecanpartitiontKecoOumnintotKetop-64productsrepresentabOeusinJsi[bitsandaOOtKerest. Top 64 traded Joods±6 bit code product CoOumn partitionsCeOO 4CeOO 1CeOO 2CeOO 3CeOO 5CeOO 6 voOprodoriJinFiJure3E[ampOeoffrequenc\partitioninJ.TKecompressionefficienc\acKievabOeb\frequenc\partitioninJbecomesmoreprominentinsNeZeddataasZeZiOOsKoZintKefoOOoZinJtZoe[ampOes.E[ampOeSupposetKataretaiOstoreisrunninJadataZare-KouseZKosescKemaissimiOartotKeTPC-DSbencKmarN.,ntKisdataZareKousetKefacttabOesstoretKedatesZKentKeproductsZeresKippedsoOdorreturnedandtKedimensiontabOestorestKedetaiOedinformationforeacKcaOendarda\.ObviousO\tKeamountsofsKipmentssaOesorreturnsarenotdistributeduni-formO\tKeseamountsareusuaOO\KiJKerontKeZeeNendtKandur-inJtKeZeeNandareespeciaOO\KiJKonKoOida\ssucKasTKanNs-JivinJDa\andCKristmas.TabOe1sKoZstKecoOumnsi]esofa1*BTPC-DSdatasetZKencompressedb\per-coOumnencodinJandper-domainencodinJ.SincetKesecoOumnsareF.coOumnsintKefacttabOestKedatesintKecoOumnsaresNeZedandKaveman\repetitions.Forcom-pressionZeuse+uffmanencodinJtomeasuretKeOoZerboundoffrequenc\partitioninJontKenumberofbits.,nper-columnencod-ingtKeencodinJofacoOumnisdoneb\usinJitsoZndictionar\totaNeadvantaJeofdatasNeZ.OntKeotKerKandinper-domainencodingtKeencodinJofacoOumnisdoneb\tKedictionar\foritsP.coOumnZKeretKereisnorepetition.TKeJainsincompressionacKievedb\e[pOoitinJdatasNeZtKedifferencesbetZeentKetKirdandfourtKcoOumnsaresKoZntobesiJnificant33%50%intKeTPC-DSdataset.E[ampOe/et¶sconsideradataZareKousetKatstorestKeen-tirepopuOationoftKeU.S.AccordinJtotKeU.S.censustKetop-1000frequentO\occurrinJOastnamesoccup\40.6%oftKeentire Kttp//ZZZ.census.Jov/JeneaOoJ\/ZZZ/data/2000surnames/ TabOe1Benefitoffrequenc\partitioninJinsNeZeddata. CoOumn OriJinaOSi]ebits CompressedUsinJSNeZbits CompressedUsinJSNeZbits TPC-DSDataSet soOd 2122 23351 44520246 returned 20044 301665 44254 soOd 4612536 15321 2321100 sKip 4612536 154600 23221450 returned 4610144 1560 233265 soOd 230202 65302 116435 sKip 230202 4634 11645361 returned 226416 50204 1111444 inv 3540000 4410000 10260000 U.S.CensusDataSet Oast name 44336 3232611 41525524 popuOation.TKusOastnamesaresNeZedandKaveman\repeti-tions.TKesi]esoftKecoOumncompressedintKesameZa\asinE[ampOe4arereportedinTabOe1andtKeJainacKievedb\e[-pOoitinJdatasNeZisaOsoquitesiJnificant21%.:enotetKatTabOe1indeedsKoZstKeadvantaJesofper-columnencodingoverper-domainencoding.TKatisZitKane[istenceofdatasNeZper-coOumnencodinJZKicKusesitsoZndictionar\andtKuscane[pOoitdatasNeZaOOoZsustoimprovecompressionratiosiJnificantO\tKanper-domainencodinJZKicKcouOdnote[pOoitdatasNeZ.E[ampOes4and5indicatetKatsNeZeddataarecommoninpractice.5.3CKaOOenJesforPartitioninJ:KentKepartitionedcoOumnsinE[ampOe3arestoredinaroZstoreorarestoredtoJetKerasacolumngroupbecausetKe\arefrequentO\accessedtoJetKersucKasandtKentKeintersectionoftKesepartitionsdefinescells.TKeseceOOscontaintKeroZsKavinJoneoftKevaOuesfromeacKcorrespondinJpartitioninZKicKeacKroZisformedb\concatenatinJtKefi[ed-OenJtKcodeforeacKofitscoOumns.,nFiJure3CeOO1containsaOOroZsKavinJeitKerCKinaortKeUSAasitsoriJinrepresentedusinJonO\onebitandoneoftKetop-64productsdenotedb\asi[-bitcode.NotetKatcodeOenJtKsarefi[edZitKinceOOsbutZouOdvar\fromceOOtoceOO.:KeneacKoftKesecoOumnsinacoOumnJrouporroZisparti-tionedtKenumberofceOOsistKeproductoftKenumberofpartitionsforeacKofitscoOumns.,nFiJure3tKe3partitionsforandtKe2partitionsforinduce2=6ceOOs.TKisquicNO\JetsoutofKandevenifeacKcoOumnKasonO\2parti-tionsoneforaOOencodedvaOuesandoneforunencodedvaOuesacoOumnJroupKavinJcoOumnsZouOdKaveceOOsZKosecon-tentsZouOdOiNeO\bever\sNeZedandsparse.TKisisbecauseoftKoseceOOsZouOdcontainroZsKavinJoneormoreunencodedvaOues.OneZa\toOimittKisproOiferationofceOOsincoOumnJroupsorroZstoresistoKaveMustoneceOOcaOOedtKecatch-allcelltoZKicKZeZiOOassiJnroZtKatKasatOeastoneunencodedvaOueinan\coOumn.E[ampOe6sKoZsane[ampOeoftKecatcK-aOOceOO.TKisscKememinimi]estKenumberofceOOsneededforunencodedvaOuesbutcompOicatesMoinprocessinJbecausenoZZeaOZa\sKavetoconsuOttKecatcK-aOOceOOinadditiontoitsencodedceOOasE[ampOe6iOOustrates.E[ampOeConsideraportionoftKeTPC-+scKemainFiJure4.OnO\tZocoOumnsoftKetabOearesKoZnintKefiJure.SupposetKedictionar\ofKastZopartitionsforandonepartitionforoZinJtofrequenc\partitioninJ.TKustZoencodedceOOsandtKecatcK-aOOceOOarecreated.TKeencodedceOOsKavetKedataintKeformofcodes.,ncontrastforuniformit\tKecatcK-aOOceOOstorestKeentireroZunencodedevenifsomecoOumnvaOuesareencod-abOe.Fore[ampOeaOtKouJKtKevaOueoftKefiftKroZisencodabOetKeentireroZisstoredunencodedintKecatcK-aOOceOOsincetKevaOue5/1/2010isnoten-codabOeduetoamissinJdictionar\entr\.TKustKevaOuee[istsintZoformsinencodedformandinunencodedform. CeOO 0 CeOO 1 CatcK-AOO CeOO Dictionar\ of /,NE,TEM 200300 /_Order.e\/_SKipDate/_Order.e\/_SKipDateFiJure4E[ampOeofdataencodinJZitKtKecatcK-aOOceOO.6.ENCOD,N*TRANS/AT,ONRecaOOfromSection3tKatMoincoOumnsarebetterencodedin-dividuaOO\³per-coOumnencodinJ´necessitatinJencodingtrans-lationdefinedinDefinition1.SinceKasKMoinst\picaOO\buiOdtKeKasKtabOefromtKesmaOOertabOetominimi]etKeKasKtabOe¶ssi]eparticuOarO\ifitsMoincoOumnisaP.itisusuaOO\cKeapertore-encodetKequaOif\inJroZsoftKebuiOdtabOesusinJtKeencodinJoftKeOarJerprobetabOe.,nastarscKematKismeanstKateacKP.ofeacKdimensiontabOeisdecodedandtKenre-encodedusinJtKedictionar\oftKecorrespondinJF.intKefacttabOeandaJainZeZiOOusetKisterminoOoJ\ZitKoutOossofJeneraOit\.ForroZstoresorcoOumnstoresKavinJcoOumnJroupstKepres-enceofacatcK-aOOceOOintroducedinSection5.3compOicatestKistransOationsomeZKatbecauseaparticuOarvaOuecanoccurintKefacttabOebotKinitsencodedforminencodedceOOsandinitsun-encodedformintKecatcK-aOOceOOe.J.tKetZorepresentationsfortKeF.vaOueinE[ampOe6.TKesemuOtipOerepresentationsfortKesamevaOueinducetZoaOternativeapproacKesforencodinJtransOationDimensionTRANSOationZKicKresoOvestKemuOtipOerepresentationsdurinJtKedimension-tabOescanandFactTRANSOationZKicKresoOvestKemdurinJtKefact-tabOescan.EacKKasitsprosandconsandisappOicabOeindifferentsituations.NotetKatputsmoreZeiJKtonreducinJtKeoverKeadofprocessinJfacttabOesZKereasstressesre-ducinJtKatofprocessinJdimensiontabOes.6.1TKeDTRANSApproacK,ntKisapproacKmuOtipOerepresentationsoftKesameF.vaOueareresoOvedattKestaJeoftKedimension-tabOescan.6.1.1HashTableConstructionOneKasKtabOeisbuiOtforaOOceOOsineacKpartitionoftKeF.pOusonetKeOastfortKecatcK-aOOceOO.TKeKasKtabOesforen-codedpartitionsareOiNeO\tobever\compactbecauseitKevaO-uesarecompressedandiieacKKasKtabOeisresponsibOeforonO\onepartitionnottKeentiretabOe.TKiscompactsi]eisKeOpfuOforimprovinJtKeprobinJperformanceintKeprobestaJe.TKeKasKtabOefortKecatcK-aOOceOOcontainsallquaOif\inJNe\vaOuesinun-encodedform.AnencodabOevaOuetKereforemustbeputintotZo KasKtabOesbecauseintKedimension-tabOescanZedonotNnoZZKicKF.vaOuesZiOOKavemuOtipOerepresentations.AOJoritKm1sKoZstKepseudocodeforbuiOdinJtKeKasKtabOes.ForeacKquaOif\inJroZoftKedimensiontabOetKeP.isdecodedusinJitsdictionar\intKedimensiontabOeandtKenre-encodedusinJtKedictionar\oftKefacttabOe/ines36.,ftKisP.vaOueisencodabOeZitKtKeF.dictionar\itscodeisaddedtotKeKasKtabOecorrespondinJtotKatF.partition/ines11.TKeP.isaOZa\saddedtotKeKasKtabOefortKecatcK-aOOceOOinunencodedform/ine12.TKisisbecauseF.vaOuecane[istintKecatcK-aOOceOOoftKefacttabOe. AOJoritKm1BuiOdinJtKeKasKtabOesin adimensiontabOedictfactdictdictfactordictisadictionar\ofafactordimensiontabOe /UTPUTasetofKasKtabOestnumpartpartofencodedpartitionsindictfactforeacKquaOif\inJroZintKedimensiontabOeloadColumnr,primaryKeyvaldecodepk,dict5/ ,fencodinJfaiOspartIdissettopartcode,partIdencodeval,dictfact/ ,fvalisencodabOeusinJdictfactpartIdnumpart/ tn]indicatestKe-tKKasKtabOe /addKeycode,HTTpartId/ encoded /endifaddKeyval,HTTnumpart/ catcK-aOO /endfor E[ampOeFiJure5sKoZstKeoutputofprocessinJascanontKetabOe.OnO\reOevantcoOumnsaresKoZnintKefiJure.SupposeapredicateisspecifiedtoseOecttKeroZsZitK³S´.AccordinJtotKedictionar\oftKefacttabOeinFiJure4tZoKasKtabOesarebuiOtfortKeencodedparti-tionsandonefortKecatcK-aOOceOO.+erein+T>0]representsZKereasin+T>1]representrespectiveO\.TKeOastKasKtabOecontainsaOO²fourintKise[ampOe²quaOif\inJNe\vaOues. O_Order.e\O_OrderStatus +asK TabOes+T>0] +T>1] +T>2]FiJure5E[ampOeofadimensiontabOescanusinJ,ftKecatcK-aOOceOOoftKefacttabOeisevercompOeteO\empt\tKismeanstKataOOvaOuesofaOOroZsoftKefacttabOeareencodedJuaranteeinJtKatever\F.vaOueKasonO\onerepresentation.AsaresuOttKefuOOdupOicationoftKeP.sisunnecessar\and/ine12inAOJoritKm1canbeb\passed.6.1.2HashTableProbeDurinJtKefact-tabOescantKeKasKtabOesconstructeddurinJtKedimension-tabOescanZiOObeprobed.,ntKeapproacKZKicKKasKtabOetoprobeforeacKpartitionispre-determinedbe-causetKeree[istsaone-to-onecorrespondencebetZeeneacKpar-titionoftKeF.anditsKasKtabOe.TKecorrespondinJKasKtabOeis :eassumetKataP.consistsofasinJOecoOumnforeaseofpre-sentation.ForacompositeNe\tKestepofconcatenatinJcodesorvaOuessKouOdprecedeZKicKKasbeenfuOO\impOementedin,:A.directO\probedZitKoutdecodinJorre-encodinJtKeF.vaOue.ForencodedpartitionstKisprobinJcanbedoneefficientO\sincetKeKasKtabOeisOiNeO\tofitintKe/2or/3cacKe.AOJoritKm2sKoZstKepseudocodeforprobinJtKeKasKtabOes.TKeaOJoritKmfirstderivestKeF.partitionoftKeceOOcurrentO\be-inJscanned/ine2andtKustKeKasKtabOetoprobeforeacKquaOi-f\inJroZtocKecNZKetKeritsF.satisfiestKeMoincondition/ines. AOJoritKm2ProbinJtKeKasKtabOesin afacttabOeasetofKasKtabOesnumpartUTPUTabitvectorVeccindicatinJmatcKinJroZsforeacKceOOintKefacttabOepartIdtKepartitionZKicKbeOonJstoforeacKquaOif\inJroZloadColumnr,foreignKey5/ ,faNe\isfound³true´isreturned /Vecci]lookupKeyfk,HTTpartIdendforendfor E[ampOeFiJure6sKoZstKeprocessofe[ecutinJascanontKetabOeusinJtKesetofKasKtabOesinFiJure5.NotetKattKeF.vaOueKasmuOtipOerepresentationsastKecodetKefirstpartitionandastKevaOueintKecatcK-aOOceOO.TKesemuOtipOerepresentationsareKandOedb\tKedupOicationoftKeP.sintotKeKasKtabOe+T>2]fortKecatcK-aOOceOO.Partition 0Partition 1CatcK-AOO CeOO +T>0] +T>1] +T>2] +asK TabOes Direct ProbesFiJure6E[ampOeofafacttabOescanusinJ6.2TKeFTRANSApproacKTKemaindraZbacNofistKeKiJKcostoftKefuOOdu-pOicationofP.s.TKiscostbecomesproKibitiveZKendimensiontabOesarever\OarJe.,ncontrasttKeapproacKaimsatavoidinJtKatdupOicationb\pa\inJanadditionaOcostintKefact-tabOescan.6.2.1HashTableConstructionTKeapproacKconstructstKeKasKtabOesintKesameZa\astKoseintKeapproacKexceptthelastonecontain-ingunencodedvalues.:KereasNeepsallP.vaOues²eventKouJKman\oftKemareencodabOe²intKecatcK-aOOKasKtabOetKeapproacKinsertsonlyunencodableP.vaOuesintotKatKasKtabOe.,ntKeencodedvaOuesandtKeun-encodedvaOuesaredisjointunOiNetKoseinSection6.1.SincenodupOicationisrequiredtKeKasKtabOesaresmaOOerandfastertoconstruct.AOJoritKm3sKoZstKepseudocodeforbuiOdinJtKeKasKta-bOes.UntiO/ine6itisidenticaOtoAOJoritKm1.,n/inespartIdparttKeP.vaOueisunencodabOeusinJtKedictionar\oftKefacttabOeotKerZiseitisencodabOe.TKustnumpartNeepsencodabOeNe\sintKesameZa\asinAOJoritKm1buttnumpartcontainsonO\unencodabOeNe\s/ine. AOJoritKm3BuiOdinJtKeKasKtabOesin adimensiontabOedictfactdictdictfactordictisadictionar\ofafactordimensiontabOe /UTPUTasetofKasKtabOestnumpartpartofencodedpartitionsindictfactforeacKquaOif\inJroZintKedimensiontabOeloadColumnr,primaryKeyvaldecodepk,dict5/ ,fencodinJfaiOspartIdissettopartcode,partIdencodeval,dictfact/ tnumpartKoOdencodabOeNe\sbuttnumpartunencodabOeNe\s /addKeycode,HTTpartIdendfor E[ampOeTKeKasKtabOesbuiOtb\tKeapproacKforE[ampOeistKesameasFiJure5e[cepttKatKasonO\tKevaOue6.2.2HashTableProbeTKeapproacKresoOvestKemuOtipOerepresentationsoftKesameF.vaOuedurinJtKefact-tabOescan.TofindtKeF.vaO-uestKatareactuallyencodablebutwereleftunencodedZeattempttoencodeeacKunencodedF.vaOueintKecatcK-aOOceOO.,ftKeencodinJsucceedstKequer\enJineneedstoprobetKeappropri-ateencodedKasKtabOefortKatF.vaOue.OtKerZisetKequer\enJineprobestKecatcK-aOOKasKtabOefortKeNe\.AOJoritKm4sKoZstKepseudocodeforprobinJtKeKasKtabOes.ForencodedpartitionsuntiO/ineitisidenticaOtoAOJoritKm2./ines23areaddedtoprocesstKecatcK-aOOceOOdifferentO\fromAOJoritKm2.ForeacKquaOif\inJroZZecKecNifitsF.vaOuecanbeencodedusinJtKedictionar\oftKefacttabOe/ines1314.DependinJontKeencodabiOit\ZKicKKasKtabOetoprobeisdeter-minedtobeeitKeroneoftKeencodedonesunencodednumpartortKeunencodedonetnumpart/ines1520.E[ampOeFiJuresKoZstKeprocessofe[ecutinJascanontKetabOeintKepreviouse[ampOe.TKeF.vaOuesintKeencodedpartitionsaretreatedintKesameZa\asinE[ampOe.TKenintKecatcK-aOOceOOtKeF.vaOueisactuaOO\encodabOeandisconvertedtotKecodeoftKefirstpartition.SotKeencodedKasKtabOe+T>0]isprobedfortKecode.,ncontrastsincetKeF.vaOueisnotencodabOeataOOtKeunencodedKasKtabOe+T>2]isprobedfortKevaOue. Partition 0Partition 1CatcK-AOO CeOO 400 +asK TabOes +T>0] +T>1] +T>2]FiJureE[ampOeofafacttabOescanusinJ.EVA/UAT,ONUsinJtKe,:AproductcodeZenoZverif\tKatMoininJencodeddataisbeneficiaOSection.2.1.:etKencontrasttKeperformanceofper-coOumnversusper-domainencodinJSection.2.2.Fi-naOO\forcoOumnJroupsandroZstorestKatuseper-coOumnencod-inJandpartitioninJtoisoOateneZvaOuesina³catcK-aOO´ceOOZecompareourtZoapproacKestoencodinJtransOationSection.2.3. AOJoritKm4ProbinJtKeKasKtabOesin afacttabOeasetofKasKtabOesnumpartUTPUTabitvectorVeccindicatinJmatcKinJroZsforeacKceOOintKefacttabOeisanencodedceOOpartIdtKepartitionZKicKbeOonJstoforeacKquaOif\inJroZloadColumnt,foreignKeyVecci]lookupKeyfk,HTTpartIdendforeOse10/ istKecatcK-aOOceOO /foreacKquaOif\inJroZloadColumnr,foreignKey13/ ,fencodinJfaiOspartIdpartcode,partIdencodefk,dictfact15/ ,fisencodabOeusinJdictfactpartIdnumpartVecci]lookupKeycode,HTTpartIdeOseVecci]lookupKeyfk,HTTnumpartendifendforendifendfor .1E[perimentaOSettinJTomeasuretKeperformanceonareaOs\stemZeimpOementedfiveaOternativeconfiJurationssKoZninTabOe2inanearO\ver-sionof,:A.KaveaOread\beene[pOainedindetaiOinSection6.simuOatestraditionaOquer\pro-cessinJb\decodinJtKecoOumnvaOuesimmediateO\beforeMoinprocessinJ.usestKesameencodinJforbotKoftKeMoincoOumnsasin>]sodoesnotrequireencodinJtransOation.FinaOO\doesnotencodevaOuesataOO.TabOe2FiveconfiJurationsusedfortKee[periments. Description EncodinJtransOationdurinJdimensionquer\processinJSection6.1 EncodinJtransOationdurinJfactquer\process-inJSection6.2 Run-timedecodinJbeforejoining Per-domainencodinJi.e.usinJonO\onedic-tionar\ZitKoutencodinJtransOation NoencodinJataOO TZoversionsoftKestandardTPC-+datasetZereusedforoure[periments.1.TomorereadiO\var\parametersandobservetKeireffectsZeinitiaOO\constructedaTPC-+datasetcom-posedofonO\one³fact´tabOeandone³dimen-sion´tabOeeacKcontaininJonO\tKetZoortKreecoOumnsreferencedintKequeriesZeran.TofocusonMoinperformanceande[cOudeotKere[pensiveoperationssucKasGROUPBYORDERBYZeusedtKeSQ/quer\beOoZ.,tsimpO\MoinsZKicKKasauniquenesscon-straintZitKZKicKKasarouJKO\uniformdis-tributiondraZnfrom.TKeOocaOpredicateon OnO\isincOudedintKereOeasedproduct. ZasomittedZKeneverZesetitsseOectivit\to1.TotesttKeeffectsofscaOinJZeJeneratedtZosi]esoftKefacttabOe²100Mand500MroZs²andfivesi]esoftKedimen-siontabOe²1.10.100.1Mand10MroZs.TKeresuOtsarepresentedinSection.2. SE/ECTCOUNT FROM/,NE,TEMORDERS:+ERE/ OrderNe\ OrderNe\ANDNOT,SNU//O Order.e\AND/ OrderNe\constant 2.Toverif\tKatoursimpOifieddatasetdidn¶tbiasourresuOtsZeaOsotestedaZidersetofqueriesonastandardTPC-+scaOefactor10datasetZKoseresuOtsarepresentedinSection.3.TKee[perimentsZeredesiJnedtovar\fourparametersitKenumberofroZsintKedimensiontabOesizeiitKenumberofroZsintKefacttabOesizefactiiitKeratiooftKenumberofunencodedroZstotKetotaOnumberofroZsratiounencandivtKeseOectivit\ofaOocaOpredicateontKefacttabOefact.TKeparameterssizesizefactZerediscussedearOier.:evariedratiounencamonJ01/161/1/4and1/2re-OoadinJtKeentiredatasetforeacK.:econtroOOedfactb\var\inJtKeconstantintKeSQ/quer\above.EacKe[perimentrantKesamequer\seventimes.Toomitpossi-bO\spuriousoutOiersZeremovedtKeminimumandtKema[imumoftKesevenrunsandaveraJedtKerest.RecaOOtKat,:Aisamain-memor\acceOeratorsotKereisnodisN,/Oinan\oftKeseresuOts.TKise[ecutiontimeisdecomposedintotKreecomponenttimesprobebuildandbaseprobemeasurestKetimeforprobinJtKeKasKtabOesandbuildtKatforbuiOdinJtKeKasKtabOes.basetKebasecostofMustscanninJtKefacttabOeZitKoutperforminJMoinsZKicKistKesameforaOOaOternativese[cept.,tismeasuredb\runninJasinJOetabOequer\²notaMoinquer\²tKatcontainstKesamepredicatesontKefacttabOe.baseisusefuOforvisuaOi]inJvariabOeportionsoftKetotaOe[ecutiontime.,nFiJ-ures12tKesetKreecomponenttimesaredistinJuisKedb\tKefiOOt\pestKedarN-soOidportionindicatesprobetKeOiJKt-soOidportionbuildandtKecross-KatcKedportionbaseasbeOoZ. probe build base AOOe[perimentsZereconductedonan,BMS\stem[equippedZitKtZoquad-core;eonCPUsand4*Bofmainmemor\.TKeCPUKasMBofsKared/3cacKe.TKeserverrunsonSUSE/inu[Enterprise10.+\per-tKreadinJisdisabOed.Ours\stemisimpOementedinCusinJ*CC4.2..2SimpOifiedTPC-+ResuOtsUntiOSection.2.2aOOtKeroZsareencodedratiounenctoconcentrateontKebenefitsofcompression.AftertKatsomeroZsremainunencodedratiounenctodiJintotKedifferencesbetZeenfactisaOZa\ssettobe1toavoidunnecessar\predicatese[ceptZKenvar\inJtKenumberofquaOif\inJroZsintKefacttabOe.7.2.1JoiningEncodedvs.UnencodedData,ncreasinJJoinPredicatesFirstZesKoZtKebenefitofMoininJencodedversusunencodedMoincoOumnsastKenumberoftKoseMoinpredicatesincreases.FiJurecontraststKeZaOOcOocNtimeoftKeMoinZitKencoded TKise[perimentrequiredsOiJKtO\var\inJbotKtKedatatoaddMoincoOumnsandtKequer\toaddMoinpredicates.coOumnsversusunencodedcoOumnsastKenumberofMoincoOumnsvariesfrom1to4ZKeresizefactsize100.ratiounenc0andfact1.0. FiJureBenefitofencodinJdata.COearO\tKeadvantaJeofMoininJencodeddataver-susunencodeddataincreasesZitKtKenumberofMoinpredicates.TKeinitiaOMumpintKee[ecutiontimeoffrom1to2iscausedb\tKetriJJerinJoftKeOoJictKatconcatenatesmuOtipOeMoin-coOumnvaOuesintocKunNseacK1632or64bits.TKereafteritsperformanceremainsconstantintKeranJebetZeen2and4MoinpredicatesbecausetKecompressionoftKeMoin-coOumnvaOuesNeepstKecompositeNe\ZitKinonO\onecKunN.,ncon-trasttKetimeforincreasessteadiO\asMoincoOumnsareaddedbecausetKeunencodedvaOuesincreasetKenumberof,ncreasinJDimensionTabOeSi]eNe[tZedemonstratetKebenefitofMoininJencodedversusun-encodeddataastKesi]eoftKedimensiontabOeincreasesfrom1.to10MroZsassKoZninFiJure.TKefacttabOeremainsfi[edat500MroZssizefact500Mandfact1.0.EacKbardenot-inJtKetimeforaparticuOarconfiJurationiscomposedofprobebuildandbaseintKeorderofappearancefromtoptobottom.JoinsonencodeddatatKefirstandsecondbarsoutperformtraditionaOMoinstKetKirdbartKatde-codetKedatabeforeaMoinb\upto40%.TKereasonsaretZofoOd.FirstdeferdecodinJuntiOaftertKeMoinisdone.SecondtKecompressedvaOuesofsuOtinreOativeO\smaOOerKasKtabOestKanforreducinJtKenumberofcacKemissesZKenprobinJtKeKasKtabOes.FurtKerin-vestiJationreveaOstKattKeOatterreasonisfarmoresiJnificanttKantKeformersincedecodinJisasimpOeOooN-upintKedictionar\soisquitefast.,ntKisfiJureareidenticaObecauseaOOdataisencodedratiounenc0.TKereOativeimprovementinprobebecomesparticuOarO\dra-maticZKentKeKasKtabOesoffitintKecacKebuttKosedonote.J.ZKensize1M.+eretKesi]eoftKeencodedMoincoOumnisbeOoZ32bitssotKeKasKtabOesofcanfitintKe/3cacKebecause32bitsMBtKesi]eoftKe/3cacKe.,ncontrasttKeKasKtabOesofareabouttZiceasbiJandKenceZiOOnotfitin/3.FordimensiontabOessmaOOertKan1MroZsbotKtKeencodedanddecodedKasKtabOesfitintKe/3cacKe.ForOarJeronesKoZ-everneitKeroftKemfit.TKisistKereasonZK\tKemarJinreacKesitsma[imumatsize7.2.2Per-Domainvs.Per-ColumnEncodingNe[tZecomparetKeencodinJoftKeMoincoOumnsusinJtKesamedictionar\per-domainversusseparatedictionariesper-coOumn.TabOe3summari]estKeconsequencestobotKtKecom-pressionratiooftKe10M-roZdimensiontabOeandtKe TKetotaOnumberofbucNetsisb\constructionabouttZotimestKeactuaOnumberofP.vaOuestominimi]ecoOOisions. :orNdoneZKiOetKeautKorZasat,BMTKisZorNisOicensedundertKeCreativeCommonsAttribution-NonCommerciaO-NoDerivs3.0Unported/icense.TovieZacop\oftKisOi-censevisitKttp//creativecommons.orJ/Oicenses/b\-nc-nd/3.0/.Obtainper-