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6/1/2015 TheSingleMostImportantThingtoKnowAbouttheOBIRPD|GreatBIWithOracleBI

https://greatobi.wordpress.com/2013/09/10/thesinglemostimportantthingtoknowabouttheobirpd/ 1/10

PostedbyJeffMcQuigg

GreatBIWithOracleBI

OracleBI(OBIEE)BestPracticesbyJeffMcQuigg

TheSingleMostImportantThingtoKnowAbouttheOBIRPD

SEP10

OvermyOBIcareerIvehadtoreviewdozensofcustomerandconsultantdevelopedRPDsaspartofeitheraformalizedhealthcheckengagementorsimplyadevelopercodereview.Frequentlythecustomerhassomeproblemsthattheycantsolve,orthattheyhavesolvedwithaworkaroundofsomesorts.Insomecasesthisissimplyduetonotfullyunderstandingtheconceptsandwhatyoucandowiththoseconcepts,butsometimesthereissomethingfarworseatplay:badadvicefromsupposedexperts.

TwicethisyearIhavecomeacrosscustomerswhohavebeentoldbyotherexpertsthatDimensionalHierarchiesarentthatimportantortheyshouldleavetheContenttabempty.OneofthesesocalledexpertswasevenanactualOracleemployee!ThisisdisastrousadviceasIwilldemonstrateinthispost.

Luckilyfollowingafewsimplepracticeswillensureyouareingoodshapeanddontenduppaintingyourselfinacorner.AlongthewayyouwillbegintounderstandhowtheBIServeractuallythinks.Onceyouareabletolearnhowtopredictwhatitwilldowith100%certainty,youcancontrolittodowhatyouwantittodoanddiagnosethesolutionswhenitdoesnt.

DimensionalHierarchiesinOBIEEareusedforavarietyofimportantfeaturesintheRPD,manyofwhichyoumaynotknowabout.Thispostwillexplorethefundamentalreasonfortheirexistenceandsomespecializedfeaturesthatrequiretheirexistence.ButmostlywelldiscussthesinglemostimportantthingtoknowabouttheRPD.



HierarchiesNotjustforDrillDown

Weallknowthatusersdrilldownalongdimensionalhierarchies,butwhatdoestheOBIBIServerusethemfor?WhenIaskthisquestion,Itendtogetalotofsilenceontheendofthephoneduringinterviews.ItisimportanttounderstandwhyweneedDimensionalHierarchiesinthefirstplace.Mygoalhereistoputtobedanyonewhosaystheyarenotneededoroptional.Illleavethemostimportantreasonforlastasitseguesintoalargerdiscussion.

1.LevelBasedMetrics

ALevelBasedMetric(LBM)isaregularmetricthathasbeenpinnedtoafixedlevelinahierarchy.ThesimplestexampleofthisisaMonthlyvalue,suchasMonthlyRevenue$.Inthisscenario,theregularRevenue$metricisfreetooperateatwhateverlevelsareneededbythequery,whetheritisthebasicgrainofthereport,asubtotalorgrandtotal,freetooperatewithdrilldownsanddrillacrosses.

TheMonthlyversionhoweverisforcingthemetrictobepinnedtotheMonthleveloftheDatehierarchy.Ineffect,itisforcingaGROUPBYMONTHinallcases.WhenyouhaveDaylevelonthereportalongwithRevenue$andMonthlyRevenue$,youcanexpecttheMonthlyRevenuevaluetoberepeatedforalldaysineachmonth.Behindthescenesthiswillbeeither2queriesoronequerywithanAGGREGATEfunctioninit.



(https://greatobi.files.wordpress.com/2013/09/lbm1.png)

ThisforcingofGROUPBYMONTHoccursintheflipscenarioaswellwhenthegrainonthereportishigherthanthatoftheLBM,itwillstillissuethatGROUPBYMONTHregardlessofthegrainofyourreport,resultinginbreakoutsandrowsyoumightnothaveexpected:



(https://greatobi.files.wordpress.com/2013/09/lbm2.png)

2.LevelBasedMetricsforNonConformedDimensions(NCDs)

ThistopicisoneofthemorecommonquestionsIseeonthediscussionforumsandwithcustomers.ThewayOBIworksmakesitmoredifficultthanitneedstobetomakeaNCDworkproperlywithotherfacts.However,thesolutiontomakingtheseNCDsworkinvolvessettingthecontenttabforeachmetrictotheTotalslevel.Effectively,youaresayingthatthemetricisattheAllorTotallevelofthatdimension,whichalsomeanstheNonelevel.Thispartgetsconceptuallytricky,buttosimplifyitjustthink:whenitsattheTotallevelforadimension,anyfilterorreferencetothatdimensionforthismetricwillbeignored.Thus,agroupbyorafilteronaNCDwhenusedwithametricattheTotalslevelwillbeignoredcompletely.

Example:

SupposeyouwantedtoseeCustomer,#SRsandOrder$amountsonasinglereport,butyouwantedtofilterdowntheSRsbasedonSRstatusofOpen.SinceSRStatusdimensiondoesnotworkwithOrderamountfacts,OBIwillnotbeabletoanswerthequestion:Order$byCustomerandSRStatus.SettingtheOrder$MetrictothetotalslevelfortheSRStatusdimensionwill



forceOBItoignorethatrelationshipcompletely,therebyconvertingitinto:Order$byCustomerUNION/STITCHJOIN#SRsbyCustomerwhereSRStatus=Open

Thistopicalonemightservewelltohaveitsownpost.However,Ihavewrittenthisupinapresentation(https://greatobi.files.wordpress.com/2011/06/mcquigg_advancedmetadatatopics.pdf)here,onpages1016

Note:SettingthetotalslevelontheContenttaboftheLTSismeaninglessandisidenticaltoleavingitblank.Ihaveseensomedevelopersbeincorrectaboutthis.

3.TimeSeries

Movingontoamorestraightforwardexample,youcannotusethetimeseriesfunctionswithoutestablishingaTimeHierarchywithappropriatelevels.

4.NestedAggregation

Nestedaggregationiswhereyoucanhavea2+stepaggregationsequence.Forexample,youmayneedaSum(Last(metric))ifyouarecomputingtotalmonthendheadcountusingdailysnapshottables.However,youneedtobeabitmoredescriptivewhenyoutellOBIthesequenceyouneedtotellitwhatdimensionsyouwanttoapplyLast()toandwhattoapplySum()tootherwiseithasnoidea.Thus,youractualnestedaggregationruleshouldbemorelike:Sum(Last(metric)byDate.Month)).Formoredetails,pleasecheckoutamorecomprehensivearticlehere(https://greatobi.wordpress.com/2013/03/21/obisnestedaggregationralphkimball/).

TheContentTab

Beforemovingontothenextfewitems,IneedtointroduceyoutotheContentTaboneachLogicalTableSource(LTS).ThistabiswithoutanyquestionthemostimportantportionofOBIRPDmodeling.Unfortunatelyitisalsotheonethatismostcomplicatedtomaster.AsaresultitisalsotheonethatisthemostincorrectandresultsinmoreRPDerrorsandproblemsthananythingelse.Inmyexperienceithasbeenandstillisthe#1causeofbrokenrepositories.

Whatissoimportantaboutthecontenttab?ThetopportioniswherethegrainofeachLTSisfullydescribedtoOBI.OBIusesthisinformationwhenpickingLTSs,bothdimensionsandfacts.ItiswhatisusedtoidentifywhatLTSisahighersource(oraggregatesource)vs.another.ThejoinstootherLTSs(acrossdim&facts)aretheskeletonoftheOBIRPDandisfundamentaltohowitoperatesandtheSQLitgenerates.ItishowitknowsthatSRStatuscanbeusedwiththeSRFactsLTSbutnotwiththeOrdersFactsLTS.ItishowitknowsthataMonthlytableisbetterthanadailytable,andwhenitcanusethemonthlysourceandwhenitcannot.



Withoutthecontenttabproperlyfilledout,therulesofhowOBIselectsaLTSbecomeabitmuddled.FranklyIcannottellyouhowitdoeswhatitdoeswithoutthem;theonlyoneswhoprobablycanaresomeoftheoriginalnQuireengineersthattaughtmetheproductmanyyearsago.Ihavealsoavoidedevenbotheringwithitbyalwayscompletelyandproperlyfillingitoutasthefirststepindiagnosingproblemsgetthefoundationsolidfirstthenworryabouttheremainingproblems.

Withoutthecontenttabproperlyfilledout,manyoftheotherfeaturesofOBIdonotworkproperly.Icameacrossaperfectexampleofthisjustlastweek.ThecustomerhadfollowedtheapproachaboveonusingthetotalsleveltodealwithNonConformedDimensions.Itwasworkingfinewhentheyhad2facttablesand2NCDs.Butwhentheyaddeda3 factand3NCD,itstoppedworkingcompletely.Thereason?TheContenttabswerenotfilledinatall.Thus,OBIdidnothaveenoughinformationonhowtosolvetheproblem.SettingupthecontenttabsonthefactsanddimensionalLTSsolvedtheproblemperfectlyonthefirsttry.

LetmereiteratehowimportantContentTabsare:WhenIdoaRPDreview,thefirstthingIlookataretheContenttabs.Iftheyaremissingorincomplete,allbetsareoff;Icannotsolveanyproblemsuntiltheyareproperlyandcompletelyfilledout.Oncethatisdone,itisquitecommonfortheproblemtobecorrectedwithoutfurthereffort,butifnotatleasttheBIServerhastherightinformationandwehavethelanguageandunderstandingtoworkwiththeRPDtodowhatitshouldbedoing.

Forthosewhostilldontbelieveme,takealookatOraclesownBIAppsRPDallofthecontenttabsareproperlyfilledout.Theengineersthoughtitwasimportanttodosososhouldyou.

Properuseofcontenttabsallowsustodoafewmoreveryimportantfunctions:

5.GrainLeveling

Thisiswhereyouwanttomixtwofacttablegrainsonthesamereport.Forexample,youdliketoshowamonthlyreportwithactualsfromtheDaytableandBudgetsfromthemonthtable.AsOBIknowsthatbothlinkintotheDatedimension,itwillissuetheappropriatequeryforeachsource.Inthisexample,itknowshowtorollupDaytoMonthandthenequalizeitwithMonthlybudgets.

6.AggregateNavigation

AggregateNavigationisafundamentalcapabilityoftheproduct.IdinfactsayAggregateNavigationisasubsetofjustgeneralLTSSelectiontheprocessbywhichOBIselectsaLTStouse.ThecontenttabtellsOBIthataLTSattheMonthlevelisabettersourcethananLTSattheDaylevel.IttellsusthatwecannotusetheLTSwithouttheProductDimensionwhenwehaveProductonthereportOBIhastochooseadifferentoneifavailable.

rd rd



7.VerticalFederation

VerticalFederationconceptuallyisverysimple:putyouraggregatetableinadifferentdatabase.Thatsallitis.Thus,youcanhaveanaggregateattheMonthlevelbuiltfromaDailytable.YoucanelecttoputthataggregateinthesamephysicaldatabaseastheDailytable,oryoucouldthrowitinanEssbasecubeoraTimesTendatabaseasExalyticsdoes.ItdoesntmattertoOBIthatmuch;itstillhastowriteaqueryandgettheresultsets.WherethedataliesdoesntmatteratalltoselectingtherightLTS.

DoingitRight

So,howaboutsomethingpracticaltofollowtomakesureyouaresetupcorrectlyfromthebeginning?Followthesethreesimplerulestoensurethatyoudontpaintyourselfinacornerandbecomestuck.Onsmallersystemsitmayseemlikeoverkill,butthepointhereistoa)getintothehabitofdoingitcorrectlyfromthebeginning,b)makesurethatthestuffyoubuildworks,c)bepreparedforwhenyourRPDgrowsmuchlargerpayadollarnowor10later.

Ifyouhaventbeenfollowingthem,Istronglyurgeyoutostopeverythingandspenddevelopmentandregressiontestcyclestoproperlyandfullysetupyourcontenttabs.Youmayfindthatitisabitpainfultoaddthesein,asyouwillstarttogetalotofRPDwarningsonConsistencyCheck,butfightthroughthemandcleanthemallup.Youmaystarttonoticethatsomeofyourproblemsdisappear.

ForeveryLogicalDimensiontable,alwaysmakeaHierarchy,evenifitisjustTotals&Details.Thisonlytakesalittlebitofeffort,andsetsyouupforalloftheitemsdiscussedinthisarticle.AlwaysfullyandcompletelyfillintheContenttabforeverysingleLTS,bothFactandDimension.Thetwowillultimatelyneedtopointtoeachother.Iftheydonot,youllgetaRPDwarning.Dothisallofthetime,nomatterifyouhaveonly3tablesinyourRPD.DoingsoenablesthemorepowerfulfeaturesofOBI,butalsomakesjustaboutanythingworkmoreproperlyinmorescenarios.DontlietoOBIaboutgrainsorHierarchystructure.Ifyoumissoneoraddanextra,ifyouassignthewronggrain,OBIwillmakeyoupayforitwithaverydifficulttodiagnoseproblem.IfarelationshipbetweentwofieldsisM:M,donotmodelthemasa1:Mparent:childOBIwillbiteyouatsomepoint.GothroughtheefforttogiveOBItherightinformationtomaketherightdecision.

ThealternativeofcourseistohaveRPDproblemsandtakemuchlongertosolvenewonesandgetfrustratedwiththeproductin



ThealternativeofcourseistohaveRPDproblemsandtakemuchlongertosolvenewonesandgetfrustratedwiththeproductingeneral.InmyyearsofworkingwithOBI,theRPDisveryreliableitgeneratestherightSQL.Ifitisnotgeneratingitcorrectly,itisnearlyalways(99.99%)thearchitectsfaultfornottellingOBItherightdetailseitherthroughomissionourincorrectly.

PostedonSeptember10,2013,inBITheoryandBestPractices,OBIEEDevelopment,RepositoryandtaggedContentTab,dimensions,Hierachies,Hierarchy,LevelBasedMetrics,Levels,NonConformedDimensions,OBIEE.Bookmarkthepermalink.7Comments.

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Comments5

obi|September11,2013at2:47pmNiceone

DougRoss|September14,2013at9:05pmGoodexplanation.

VenkatG|September28,2013at5:37pmHiJeff,ThanksalotforsharingsuchgreatRpdmodelingtechniquesthatveryfewpeoplereallyunderstandsandfindstimetoshareknowledgewithOracleBIcommunity.iwishyouwouldfindtimetowriteafullbookonthistopicOracleBIMetaData

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ModelingCompleteReferencePracticalApproachforRequirementsModeling

IhopewewillseemanymoresuchmodelingtechniquesandprojectimplementationmethodologiesforOBIAProjectsonyourblog

CongratsforyourrecentOracleprojectexcellenceawardforHRAnalyticsproject,

VenkatG

rmoff|October30,2014at5:25amJeffgreatarticle.AnycommentsontheCheckLevels/GetLevelsfunctionintheAdminToolwhendefininganLTScontent?Itfrequentlysuggestsblanksfordimsagainstafacttable,whichrunscontrarytoyouradviceAlwaysfullyandcompletelyfillintheContenttabforeverysingleLTS,bothFactandDimension.

thanks,Robin.

JeffMcQuigg|October30,2014at7:54amHeyRobin,

Ifitleavesthemblankitsbecauseitdoesntworkproperly,notbecauseitthinksitsoktoleavethemblank.IdonttrustmanyoftheautomatedpiecesofwhattheAdmintooldoes,insteadpreferringtheapproachofthedeveloperknowingexactlywhatshouldbedoneandthendoingit.SamethinggoesforwhenyouimportphysicaltablesyouneverimportFKs.Dothemyourselfsoyouknowexactlywhatishappening.IdontlikeunintendedconsequencesintheRPDduetoinaccurateoroverlyaggressivecode.

Iwasusingitjustyesterdayanditgotafewthingswrong.Sono,Idrecommendnotusingitunless(likeIwas)youareinabrandnewRPDyouveneverseenanditcanpointyouintherightdirectionwithdimensionsyouareunfamiliarwith.

JeffM.

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