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11/7/2014 RittmanMeadConsultingTheMysteryofOBIEEBridgeTables

http://www.rittmanmead.com/2008/08/themysteryofobieebridgetables/ 1/12

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RittmanMeadDeliveredIntelligenceTheMysteryofOBIEEBridgeTables

August28th,2008byMarkRittman

IfyouveplayedaroundwiththeOracleBIAdministratortoolforawhile,youmayhavenoticedaboxyoucantickintheLogicalTablePropertiesdialog,calledBridgeTable.IfyourefamiliarwithRalphKimballandsomeofthisdimensionalmodelingideas,youveprobablyheardofthisconceptbefore,butitsnotallthatclearhowyouusebridgetablesinOBIEEandaquicksearcharoundtheinternetandtheOTNforumsdoesntreallycomeupwithanexamplesonhowitsused.

Bridgetablesareasolutiontowhatscalledthemultivalueddimensionproblem.Formostdimensionalmodelsyougenerallywanttolinkonesale,forexample,tooneproduct,onecustomer,onetimeperiodandsoon,andthistranslatesintoasimpledimensionalmodelwhereyourfacttablecontainsasinglekeyvalueperdimensionforeachrowthatsbeenstored.Insomecircumstancesthough,saywhereyouarerecordingthediagnosesforapatientortheclaimelementsinaclaim,youmightneedtorecordmorethanonekeyvalueforaparticulardimensionineachfacttablerow.Inentityrelationshipmodelingterms,youvegotamanytomanyrelationshipbetweenpatientadmissions



anddiagnoses,likethis:

andtheusualwayyouresolvethesemanytomanyrelationshipsistouseanintersectiontable,withthekeyfromthepatientadmissionstableandthekeyfromthediagnosestablecopiedacrosstoformtheintersection,andusuallywithaweightingcolumnthataddsupto1,sothatyoucanproperlyaddupallthediagnosesandnotovercountthem.

AsIsaid,thisisnotexactlynewstuffandbridgetables,ofwhichdiagnosisgroupaboveisoneofthem,areafairlycommondimensionalmodelingconstruct.Theproblemyouhitthoughwhenstartingtousethisfeatureisthatthedocumentationonitisprettyminimal,andonlyreallytalksaboutsettingthisfeatureonthebridgetableitselfanddoesntreallymentionwhattodowiththedimensiontablethathangsoffofit.WhatIlldointhispostingthenissetouthowIuseit,explainmyrationaleandthereafterinvitesomefeedback,soifsomeoneelsehascomeupwithabetterideathenwecanworkwiththatinstead.

GoingintoBIAdministratorandlookingatthephysicalmodelforthedatasetabove,itlookslikethis:

withthekeythingherebeingthatthefacttablewevegotthebridgetablejoiningtoboththefactanddiagnosisdimtablestoformanintersection.Ifyouimportedthismodelintothelogicalbusinesslayerasis,theBIAdministratorwouldthinktheintersectiontableisthefacttableastheothertablesjointoit.

Sowhatyoudonowisgointothepropertiesforthediagnosistableandindicatethatitsabridgetable,likethis:



Nowwhenyoulookatthelogicalmodelthefacttableisidentifiedcorrectly.

Ifyoutryandvalidatethemodelnowthough,yougetawarningbecausethediagnosesdimensiontabledoesntlinkthroughtothefacttable,asitgoesthroughthebridgetableinstead.

Nownotlinkingthroughtothefacttableissometimesallowed,basicallyinsituationswhereyouvesnowflakedyourlogicalmodelandthedimensiontableisactuallyahigherlevelinthesamedimension,butinthiscaseifwetryandusethismodelandbringinthediagnosesinformationintoaquery,wellgetametadataconsistencyerror.

Tosolvethis,whatIwoulddoisremovethediagnosisdimensionfromthelogicalmodel,andinsteadaddittothelogicaltablesourceforthebridgetable,likethis:



ThenIdaddanycolumnsthatIneededfromthediagnosisdimensionphysicaltableintothebridgetable,whichIcandonowasIveaddedthedimensiontabletothebridgetableLTS,sothatthisbridgetablenowbecomesmydiagnosisdimension,likethis:

SowhatIvedonehereistakethedimensiontable,whichbeforelinkedtothebridgetableandthereaftercausedthemetadatainconsistency,andinsteadaddedittothebridgetablelogicaltablesourceandaddeditscolumnstothebridgetablelogicaltable.

IfIrunareportnow,thedatacomesoutasyouwouldexpect,withmultiplediagnosesperpatientandtheweightingappliedcorrectly.



HoweverImconsciousthattome,gettingridofthelogicaldimensiontableseemsabitwrong,andothershavesaidthattheydontusethebridgetablefeatureatall,andinsteadjustcombinethevarioustablesintoasinglelogicaltablesource.Ifanyonesgotanyotherwayofusingbridgetables,addacommenttothispostandwellseewhattheconsensusis.

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1. MikeNicholsSays:

August29th,2008at12:52am

ThanksMarkforthegreatpost.IhavespentthelastyearrelearningmyDiscovererskillsonOBIandhaveappreciatedyoruposts.LookingforwardtoOpenWorld.Iwonderifyouhavetriedstartingwithaviewthatprejoinsthebridgetableandthedimensiontable.ThenusetheviewasasourceinOBIEE.HowdoesOBIhandlethistypeofsituation.CurioushowtheSQLcomesout.ThisishowInormallysolvethebridgetableforusersanyway.Ifindwouldimporttheviewindiscoverertohidethecomplexityofthebridgefromtheendusers.Whatareyourthoughts?

2. GerardBraatSays:

September2nd,2008at9:15pm

HiMark,Thanksforthepost.Ithinkyoudonotneedtodeletethedimensiontable.ByjustaddingtheDIMtablealsotoLTSofthebridgebutleavethedimtableinthelogicalmodel,youresolvetheinconsistencyandleavethemodelintuitiveandintact.However,thepurebridgetablesituationinaDWHstarschemaisslightlydifferent:Itisadimensionjoiningtoafact,saySALES_REP_DIMtoCOMPENSATION_FACTwhichjoinsviaabridgetoSALES_TEAM.InthiscaseyoucannotaddtheSALES_REPdimensiontothebridgebecauseitdoesnotjointothefactandhencedoesnotsolvetheproblem.THeotherwayaroundisnotallowedsincethegranularityofthebridgeishigherthanitsatellitedimensions.Ihave,untiltoday,nosolutionforthisproblem.I

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amkeentodiscoverwhattheeffectisintheOBIEEserverengine,ofcheckingtheBridgeTablebox.Tobecontinued

Cheers,Gerard

3. MarkRittmanSays:

September3rd,2008at10:13am

HIGerard,Mike

Mikethanksforthecomments.IntermsofdefiningaviewoutsideofOBIEE,asyousaythisprobablymakesthingsaloteasier,howeverforthisinvestigationIwastryingtoseehowOBIEEuseditsbridgetablefeaturehencegivingitago.Asyousaythough,resolvingtheissueinthedatabaselayerpriortomanipulatingitviaBIAdministratorisoftenthesimplestapproach.

GerardIthinkIdidtryaddingthedimtothebridgetableLTSandIgotthesameerror.IlltrythisagainwhenIgetamomentandseeiftheproblemstilloccurs.Thanksfortheheadsupontheotherbridgetablescenario,ifyougetasolutionthenletmeknow,Illkeepaneyeopenaswellforthis.

4. JohnBroadwaterSays:

September11th,2008at6:18pm

Thesearegreatposts.Veryclearandveryvaluable.Ingeneral,thispostdescribeshowIhaveusedbridgetablesinotherenvironmentsEndusersjustseeasingleviewcombiningthebridgeandthebridgeddimension.

Myquestion:arethereanyfrontendquerytoolssmartenoughtoautomaticallyapplytheweightingfactortoreferencedfactamounts?

5. SammySays:

October24th,2008at9:16am

IthinkthemultivalueddimensionsolutionliketheloopsolutioninBO.Maybethatneedaverymatureandcomplexsolutionsupply.

6. SanSays:

November20th,2008at8:25am

HiMark,ThisisthewayImodeleditanditworkedfineforme.InsteadofusingtheBridgetabletojointothefactthewayIdidiintheBMMlayerisiJoinedtheDimension(Diagnoses)totheFacttableandinsidetheLTSofdimensionImappedthebridgetableastheothersourceanditworksfineformeanditgivsmecorrectresult.Pleaseadvice.Regards,San

7. ParagSays:

March12th,2009at4:38pm

HelloMark,Thanksforallthepostsandinsights.Theyareextremelyhelpfulinthedesignanddevelopment.

Ihaveaquestion.Wouldthisapproachworkwith2facttables,evenifthereisaconfirmeddimensionbetweenthe2.



Thefactgroupsarejoinedusingthethehierarchiesanddefiningcontentlevelforthefacts,dimensionsandmeasures.Butthequeriesarelengthyandlongrunning.

Thanks,Parag

8. BibudeshSays:

July3rd,2009at5:00am

HiMark,Ithinkhavingabridgewillbemorebeneficaliftherearetwoormoremultivalueddimensions.Ifitsonlyonethenitsbettertohaveboththedimensionsinfactitselfandhavetheweightfactorortheproratafactormaintainedinthefact.Thiswillreducecomplexitywhileauditingtheresultsandendqueries.RegardsBibudesh

9. RoySays:

August11th,2010at9:13am

HiMark,

Thisisaverygoodpostandhelpful.CanyoupleasegiveanexampleofPatientAdmissionandDiagnoseswithsomerecordsandshowhowtheylooklikewhenDiagnosesGroupiscreated,too?Iamnotabletounderstandhowtomovethekeysfromthosetwotablestothebirdgetabletoconvertmanytomanyrelationshipintotwoonetomanyrelationships.

Regards,Roy.

10. MohammadRafiAnsariSays:

September1st,2010at10:08am

CanyoupleaseshareRPDforTheMysteryofOBIEEBridgeTables.


September1st,2010at10:10am

HiMark,

Thisarticleisreallynice.ifpossiblecanyoupleasesendmeTheMysteryofOBIEEBridgeTablesrpdatrafiansari2002@gmail.comIwillbethankfulltoyou.

RegardsMohammadRafiAnsari919213626363

12. MarkRittmanSays:

September1st,2010at1:59pm

HiMohammad,

ImafraidIvenotgotitavailablenow,thepostingis>2yearsoldnow,sorry.

Mark




September3rd,2010at5:42am

HiMark,

Thanksforurreply.

ItsokifRPDisnotavailablenowIwilltrytodoitbymyself.WellIneedsomemorehelpfromyourside.ActuallyIamplanningforOBIEECertificationbutidontknowwhatwillbethepatternforthat.SoIneedyouprecioushelp,ifyoucanarrange/providemeanysoftmaterialoranysamplepaperoforacleforstudy.Sothaticanscoremoreinpaper.

RegardsMohammadRafiAnsariEmail:[email protected]:919213626363

14. JebySays:

September19th,2010at6:52am

HiMark,

Usefularticlethatshowsonemorewayhowtobridgetables.IwasperforminganupgradefromSiebelanalyticstoOBIEE10.1.3andwehadlotsofconsistencyerrorspostupgradewhichwerenotvisibleinanalytics.Theyseemedtobearisingfrombridgetables(althoughtheerrorswereonBMMobjectsnotevenrelatedtothebridges).OurOracleconsultantjustdeletedthebridgetablesandalltheerrorsvanished.Iwasalsosurprisedtoseethatallthebridgeshavingthesourceasfacttables.Canyoupleaseshareyourthougtsonifandwhenyouconsiderafacttabletobehaveasabridge?

15. RobSays:

October6th,2010at7:28pm

Thankyouforsharingyourexpertisethisarticlesavedmequiteabitoffrustration.Isubscribetoandamimpressedbyyourrssfeed,aswell.Rockon!

16. FrankSays:

October14th,2010at3:08pm

ThebridgetableoptionisnotavailableanymorewithOBIEE11g.Ithasbeenchangedwithaninterestinglookuptableoptionwhichofcourseisnotthesamefonctionnality.

Regards

17. saudSays:

January17th,2012at12:04pm

awesome

18. DSSays:

August28th,2012at10:46pm

MarkyouaretheexpertandIhavebeenstrugglinginthisonething.IwanttomakeaMasterDetailreportto



workwheremasteriscomingfromoneFacttableanddetailiscomingfromanotherFacttable.However,theybothsharedcommondimensionsandtheyareinsamesubjectarea.

19. DavidSays:

September10th,2012at7:31pm

Hi,Nicearticleithelpmetounderstandmanythings.IalsohaveaproblemwhichIwantyoutohelpme.Thisisjustasimpleexampletoilustratemyquestion.

Facttable:PERSON_ROLE

DimensionaltablesDIMPERSONPersoncatalogDIMROLERolebyPerson{DIM_PERSON_ID,ROLE_Name}soitislikeabridgeplusdimensional

APersoncanhavemultiplesroles,butintheFacttableimonlyusingoneregisterperperson.

myFacttable{DIM_PERSON_ID,DIM_GROUP_ROLE}

inthissimplecasecouldIusethesamevalueforbothcolumns?oricanbindmytwodimensionstosinglecolumnontheFacttable?

Thanks

20. LakshmananSays:

September28th,2012at3:00am

WehaveaBalancedScoreCardwhichshowsKPIfigures.OndrilldownthisshouldshowAccountcategoryfigures.

ManytoManyOneKPIreferstomanyAccountcategories.OneAccountcategoryisusedinmanyKPI.

TherearetwowaysofjoininglogicaltableswithabridgetableinOBIEE10g.

Afterjoiningyoucancopyandpastethetablecolumnsintoonetableorletthembeintwotables.

Butthefiguresarecomingwrongaftersuchjoin.Afterstrugglingforonemonth,wegaveup.

TomakethissimplewesimplymergedtheDim_KPIintotheDim_Accountsphysically.Thestructurelooksfunnywith200columnsinDim_AccountsforeachKPI.ButthenthisiswhatOBIEEdoeswithlogicaltables.Andwedonothavewrongfiguresproblem.

AnditisveryeasytoverifyanaccountbelongstowhichallKPI.

AddinganewaccountiseasyweexportthetabletoanxlsforfinanceguytoaddnewaccountandmentionunderwhichallKPIitshouldbereferred.

21. AnirbanSays:

January16th,2013at2:11pm

HiMark,

Thanksverymuchforthepost.Itisreallyveryveryhelpful.JustwantedtoknowifIwanttoimplementthebridgetableconceptiOBIEE11.1.1.6,howIcanimplementitasthereisnooptionforBridgetableinOBIEE



11.1.1.6.

ThanksAnirban

22. OsamaAbdallahSays:

July2nd,2013at4:16pm

HiMark,

Thankyouforthegreatpost.IbelieveIhaveasolutionforyou.Youcanbypassthebridgetablesolutionaltogetherbycreatinganaliastableofthesecondfacttable,andlinkittotheprimaryfacttableinthephysicallayerasonetomany.ThenintheBusinessModelandMappingLayer,youcanmergethealiasfacttablethroughtheLTSwiththeprimaryone.MakesuretocreatethejoinsofthetwotablesintheirLTS.Sonowyoudendupwithonebigfacttable.YoucanthensplitoffthatbigfacttableintotwotablesinthePresentationLayer.

Ivehadalmostthesameexactscenarioatwork,whereIneededtomergeanothertablewiththemainfacttable.AndthisistheapproachthatItook.InthePresentationLayer,Ididputitasonefacttable.ButlikeIsaid,youcansplititintomultipletables.

Idontthinkthebridgeoptionisreliable.Itriedit,anditfrustratedme:).ItsoneofthesethingsthatOraclesometimesputsouttherethatdontwork.Butthecustomerspayforthemanyway.hehehehehhe.

Takecare,OsamaAbdallah

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