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限制,如果WHERE子句的查询条件里有不等号(WHEREcoloum!=),MySQL将无法使用索引。类似地,如果WHERE子句的查询条件里使用了函数(WHEREDAY(column)=),MySQL也将无法使用索引。计划|数据
EndUsers
Theendusersarewhoyouaredesigningandbuildingthedatawarehousefor?yourcustomers.Theyrelyontheinformationtheyextractfromthewarehouseinordertoworkmoreeffectivelyandefficiently.Theyalsoultimatelydeterminewhetherornotyourdatawarehouseprojectmetitsstatedgoals.Forthesereasons,yourprojectmustbebuiltaroundprovidingtheenduserswiththeinformationtheyneedinauser-friendlyfashion.
Theprimaryendusersfordatawarehouseinformationarereportrecipientsandquerydesigners.Theyprovidetheresultsoftheirworktothedecisionmakerswhodeterminethecourseofyourorganization.
ReportRecipients
Reportrecipientsaretheendusersmostdependentupontheinformationextractedfromthedatawarehouse.Theyincludebusinessanalysts,financialanalysts,mid-levelmanagers,seniormanagersandexecutives.Althoughsomeofthereportrecipientswillhaveparticipatedinthedesignprocess,theywillhavedifferentperspectivesasendusers.Theywillhavethegreatestinterestsinreportcontentformatandrequirements,timeframeandupdatefrequency,adhocquerycapabilitiesanddrilldown/drillthroughrequirements.
Reportcontentandformatrequirementsdefinewhatinformationispresentedandarranged.Yourenduserswilleachhaveaspecialperspectiveonwhatinformationisimportantintheperiodicreportstheyrelyon.Manytimestheywillneedsimilarsourcedata,butthereportswillcontaindifferentcalculatedvaluesandextrapolations.Evenwhentheyagreeonwhatinformationmustbepresent,theyeachhaveadifferentsetofrequirementswhenitcomestohowtheinformationisarranged.Eachoftheseviewsmustbetakenintoconsiderationwhendefiningyourprojectrequirements.
QueryDesigners
Querydesignersaretechnicallycompetentpeoplewhoaretaskedwithbuildingthequeriesthatprovidethereports.Theyhavetopleasethereportrecipientswhileworkingunderthoselimitationsimposedbythestructureandcontentofthedatawarehouse.
Thequerydesignersareavaluableresourceinthesameareasasthoserepresentedbythereportrecipients,butfromadifferentperspective.Theyfrequentlyaskyoutoincludecalculatedcolumnsthereportrecipientsdontknowarenecessary.Theyalsoaskforsimplerstructureinmanyareas,soastomaketheirquerydesignsmoremanageableandalsodemandhighlydenormalizedtableswhereverpossible.
Management
Managementwilltypicallyprovidethemostdemandingandleastdetailedsetofrequirementsfromthedatawarehouseproject.Youcanexpectsuchrequestsas,"Ineedtoknowhowprofitableweareonaquarterlybasis."or"Whoareourtop100customers?"Youwillthenhavetoworktodefineprofitabilityandtopcustomerintermsthatcanbeappliedtothedatawarehouse.
Managementrequirementsusuallyfallintothreegeneralcategories:strategicreportingandprojections,tacticalreportingandenterprisestandardscompliance.
StrategicReportingandProjections
Strategicreportingandprojectionarelongtermprocessesaimedatpositioningtheorganizationtoremaincompetitiveinthemarketplace.Strategyisdefinedasaplandesignedtoplaceanorganizationinanadvantageouspositionpriortocompetition.Fromthiswecanseethattheinformationneededtosupportstrategicinitiativesconcernslong-termtrendandmarketpenetrationanalysis,long-termrawmaterialinventoryavailabilityandusage,changesinthetechnicalenvironment,workforceprojectionsandcustomerdemographicinformation.Eachmanagementteamwillhaveitsownlistofspecificinformationtheyneedinordertohelpthemformulateoradjustthecorporatestrategy.
TacticalReporting
Tacticalreportingdealswithunderstandinghowday-to-dayoperationsaremeetingstrategicobjectives.Theseshort-termreportsmayconsistofdaily,weekly,monthly,quarterlyorannualanalysesofthecurrentstateofaffairswithintheorganization.Thesereportswillcontainoperationalinformationonsalesstatistics,workforceutilization,inventorymanagementandmeasuresspecifictoeachindustry.Thetimelinessofthesereportsrequiresinformationbemadeavailableasrapidlyaspossibleafteritiscaptured.Itisnotunusualformanagementtorequirethatdailyreportsbeavailablewhentheyarriveforworkonthefollowingday,orthatweeklyreportsbeavailableby9:00AMonMondaymorning.Yourdatawarehousewillhavetobetunedtoprovidetherequiredlevelsofperformance.
EnterpriseStandardsCompliance
Enterprisestandardscomplianceconsistsofinsuringthatallpartsoftheorganizationareworkingintheacceptedmanner.Thereportsthathelpmanagementdeterminetheextenttowhichthisistruecanrangefromverysimple,withonlyafewrows,eachcontainingonlyfourorfivecolumns,tocomplex,multi-pagereports,supportedbypivottablesandcharts.Theextenttowhichyourmanagementteamwishestotrackstandardscompliancewilleffectthelevelofdetailthatyouwillneedtocapture.Forinstance,shouldthemanagementteamwanttoinsurethateachworkgroupiscomplyingwithcorporatestandardsregardingworkhoursandbreaktimes,yourwarehousewillhavetocontainallthepertinentdataoneachemployeesscheduleoveraspecifiedperiodoftime.Youwillalsohavetobuildsummarytablestosupportmoregeneralanalyses.
SystemsStaff
Yoursystemsstaffmemberswillhelpidentifythebesthardware,softwareandconnectivityconfigurationsforyourwarehousingoperation.Theyalsowillhelpyouidentifytherisksandlimitationspresentedbyeachpossibleconfiguration.
Hardware
Hardwareconsistsofalltheprocessing,storageandperipheralcomponentsuponwhichyourdatawarehouseoperationwillreside.Yoursystemsspecialistswillhelpyoumakeintelligentandinformedchoicesregardingmainframe,mid-range,mini-computerorpersonalcomputerprocessing;multipleprocessing,eitherparallelordistributed;distributedorconcentratedstorage;andallthedecisionsthatdeterminethephysicalstructureofyourwarehouseenvironment.
OperatingSystemandSoftware
Insomecases,theoperatingsystem(OS)andsoftwarechoicesavailabletoyouwillbedeterminedbyyourhardwareselections.Inothercases,thehardwarechoiceswillaffect,butnotdictate,theOSandsoftwareoptionsavailabletoyou.Yoursystemsspecialistswillworkwithyoutodeterminewhichcombinationsfityourprojectsneedswhilecomplyingwithcorporatestandards.
Connectivity
Connectivitydealswithallthecomponentsandassociatedcommunicationsthatallowonecomputertosendandreceiveinformationfromanother.Yoursystemteammemberswillprovideyouwithvaluableinformationregardingthechoicesavailable,recommendedconfigurations,currentlyimplementeddesignsandanyenterprisestandardsyourprojectmustcomplyto.
SecurityStaff
Yourorganizationssecurityspecialistsfallintotwomaincategories,information/systemssecurityandfacility/physicalsecurity.Ineachcase,thesespecialistswillprovideyourteamwithinformationvitaltothesuccessofyourproject.
Information/SystemSecurity
Informationandsystemsecurityissuescenteronthreeprimarycategories:authentication,authorizationandusecontrol.
Authenticationistheprocessofinsuringthataparticularindividualisaccuratelyidentified.Authorizationdealswiththosemechanismsthatpreventapersonfromgainingaccesstoapplicationsordatabasestheyshouldnothaveaccessto,whileinsuringaccesstoapplicationsordatabasestheyhasobtainedapprovalfor.Usecontrolisconcernedwithlimitingeachindividualtooperationsthathavebeenidentifiedasappropriatefortheirjobandoperationalfunctions.
Facility/PhysicalSecurity
Facilityandphysicalsecurityissuesareconcernedwithwhereandwhenparticularindividualsmaybeincorporateproperties,whattheycandowhilethereandmakingsurecorporatepropertyissecuredagainstmaliciousdamageandtheft.Threeofthecategoriesoffacilityandphysicalsecurityarethesameasthoseforinformationandsystemsecurity:authentication,authorizationandusecontrolaswellaslossprevention.
Asisthecasewithinformationandsystemsecurity,authenticationistheprocessofinsuringthatanindividualis,infact,whotheypurporttobe.Authorizationconcernstheprocessofallowingonlythosewiththeproperclearancestoenterspecificareaswithincorporatefacilities,whileprovidingcompleteandreadyaccessforthosewhoshouldbethere.Usecontroldealswithinsuringeachfacilityorphysicalstructureisusedinaccordancewithcorporatepolicy,andthosepresentcomplywithallsafetyandregulatoryrequirements.Losspreventioninvolvesprotectingbothcorporateandpersonalpropertyfromtheftorlossthroughothermeans(fire,vandalism,etc.),aswellasprovidingforthesafetyofthoseindividualswhoareworkingatorvisitingatthefacility.
PhysicalMaintenanceStaff
Thephysicalmaintenancestaff?janitors,plumbers,electriciansandfacilitiesplanners?canprovideadditionalinformationtoyourprojectteam.Althoughthisgroupisseldomincludedinprojectrequirementsplanningsessions,theirinputcanbeessential.
Facilities
Assessingthefacilitiesavailabletoyourprojectteamforthedesignanddevelopmentphases,aswellasidentifyingthephysicallocationsforhardwareandforthelong-termwarehouseoperationsteamarevitaltoinsuringtheprojectcanbecompleted.
Ifyouareunabletofindworkspaceandmeetingroomsforyourteammembers,theprojectwillbedelayedatbest.Ifyoufailtoidentifytheroominwhichyourdatabaseserverwillbelocated?andreservetherequiredspaceandutilitiesassoonaspossible?youmayfindyourselfwithacompleteprojectplanandexcellentdesigndocumentation,butwithnoplacetosetthehardware.
Youwillalsoneedtoverifythatteammemberscanaccess,bothphysicallyandthroughtelecommunications,thevariouslocationsassociatedwithyourproject.Theyalsoneedtoknowthedatesandtimesaccessisvalidforeachfacility,andwhat,ifany,priornotificationsandapprovalsarenecessary.
Foreachoftheinvolvedfacilities,youneedatleastsomeparticipationfrompersonnelassignedtothatfacility,primarilythefacilitiesmaintenancestaff.Thesearethepeoplewhocanbestadviseyouonthosefactorsthatwilllimityouroptionsinthisrespect.
MaintenanceSchedules
Thefacilitiesmaintenanceteamswillalsobeabletoadviseyourteamastoscheduledmaintenanceactivitiesthatwillaffectyourprojectschedule.Suchmaintenanceactivitiesinclude:newconstruction,repairs,telecommunicationsupdates,powergridmaintenanceandlargescalepersonnelrelocations.
Thefacilitiesteammemberswillalsobeabletoadviseyourprojectteamonestimateddowntimesforunscheduledmaintenanceactivities.Theseactivitiesaretypicallyassociatedwithexternalproblemscompletelyoutsidethecontrolofyourorganization.Yourorganizationwillmostlikelyhaveaplaninplacefortherestorationofservicesshouldanysuchproblemoccur.Thisistheinformationthatthefacilitiesteammemberscanprovideandthussaveyourteamtheeffortofreconstructingthesupportingestimatesanddisasterrecoveryplans.
由MySQL用来存储数据的文件格式以已经被广泛地测试过,但是总是有外部情况可以导致数据库表被破坏: |
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