MYSQL教程之Oracle已过期？
客户还是可以使用DBaaS系统所能提供的所有能力。数据库云服务消除了组织对专职人员、本地数据库存储设备的需要。他们不必安装、配置和维护任何软硬件。oracle转自MarkRittman的BLOGhttp://www.rittman.net/archives/001130.html
IsOracleALegacyTechnology?
OneofthenicethingsaboutworkingwiththeOracleRDBMS,comparedtosayworkingwithtechnologiessuchasAS/400,COBOLormainframesisthatitsgenerallyperceivedasa"hot"technology.SalarysurveysshowOracleskillsasbeingoneofthemostin-demandskillsets,theOracledatabaseiswayaheadofthecompetitionintermsoffeaturesanduseofnewtechnology,andmostoftheworldstopcompaniesuseOracleastheirdatabaseofchoice.ButwhatifinfactwevegonepastthepeakofOraclesascendancy,anditsnowalegacyproduct,withallworkinfuturebeingmainlyaboutmaintainingsystemsinplace,andmigratingthemtonewer,morefashionablesystems?AcoupleofexcellentrecentarticlesbyMogensNørgaardraisedthisasapossibility,andcertainlygiveyouafewthingstothinkoverwhenyouconsidertheOracledatabasetechnologystack.
ThefirstarticlewasattheendofMogenschapterinOracleInsights:TalesOfTheOaktable,wherehelooksatthekeyfactorthatmakesOracleparticularlysuitedtoeffectivetuning-thefactthatthedatabasekernelisheavilyinstrumented(thefamous"waitinterface"),andbecauseofthis,youcanobtainprecisedetailsaboutexactlywhatisslowingdownyourapplication.Otherdatabases,suchasDB2andMicrosoftSQLServer,donthavethisinstrumentation(oratleastitsnotpubliclyaccessible)andthereforeitsmuchmore"hitandmiss"withthoseplatforms.
ApointthatMogensmakesmid-waythroughthearticlethoughisthat,whilstitsallwellandgoodinstrumentingthedatabase,inmostcasesanapplicationconsistsofaSAN,operatingsystem,anapplicationserver,applicationcodeandsoon,andifyouveonlygotfeedbackonhowthedatabaseisperforming,youveonlygotpartofthestory.Mogensmakesthegoodpointthat,whilstMicrosofthaventexposedSQLServersinternalsinthesamewaythatOraclehave,infacttheyvegotahistoricalchancetoinstrumenttheentireapplicationplatform,astheyownthetechnologybehindWindowsServer,IIS,.NETandsoon,apointmadeagainbyNiallLitchfieldinathreadoncomp.databases.oracle.server.
Wherethisgoesontothoughisthat,whilstitsfantasticwhatOraclesdonewithinstrumentingthedatabasekernel,whatMogensisactuallyfindinginreallifeisthat,likediskstorageandoperatingsystemsbeforeit,thedatabaseitselfisnowbecomingacommodity,withno-onethesedaysgettingfiredforbuyingMicrosoftSQLServer,andmanyorganisationslookingtoopensourcedatabasessuchasmySQLtohandletheirday-to-daydatabaseneeds.Whilstthisismovingdatabasesasawholeintothelegacycategory,itparticularlyhurtsOraclebadlyasfirstly,theOracleRBDMSisexpensiveandstilltothisdayrequiresalevelofadministrativeskillwellaboveSQLServerandmySQL,andsecondly,forOracle,databaserevenuesarestillthemajorityoftheirtotallicenserevenues.Accordingtothearticle,
"OracleandDB2arenowlegacydatabases:veryfewtrulynewsalescomparedtolicenserenewalsandadd-onsalestoexistingcustomers,veryfewyoungpeoplecomingoutofschoolswantingbadlytolearnaboutthem.SQLServeristhesafechoicethatwontgetyoufired,andtheopensourcedatabasessuchasmySQLwillprevailwhentheycandelivertheneccessary(ratherfew,basic)functionalitiesthatthedevelopersoftomorrowwillrequire(suchashandlingtransactionscorrectly,havegoodbackupmethods,andsoon)."
TheironyasfarasMogensisconcerned,isthat"wheneverasystemortechnologyreachesalevelofperfection(inotherwords,scienceisusedasarule)itwillbereplacedbysomethingmorechaoticthatlooks(andperhapsevenis)cheaper",somethingthathappenedtomainframesbeforeand,justatthepointwhereitreachesthelevelof"technicalperfection",couldpossiblybethefateoftheOracleRDBMSitself.
MogensmadethesamepointsagaininhiscolumnintheAutumn2004editionofOracleScene,and,thinkingabouttheearlierpointaboutdatabasesingeneralbeingmadeintoacommodity,saysthatthiswillhavethefollowingeffectondatabaseprofessionals:
"SotheDBAsareslowlybeingreplaced,outsourced,divertedtoothertasks,orbeingaskedtofocusonotherthings,too.Thatmeansthreethingsforourdatabaseworld:
1.Thedatabaseswillusuallyrun,becausenobodyisfiddlingwithparametersandotherstuff.
2.Nonewfeatureswillbetestedandimplemented(afterall,7.3isstillplentyofdatabasetechnologyformostuses).
3.Whenthingsfinallygowrong,alotofothercomplications,duetothelackofdailynursing,fiddling,andcaring,willbediscovered,makingthetroubleshootingandrestore/recoveryprocessevenharderinanevenmorecriticalsituation.
Itmeanssomethingelse,too:Forcompaniesspecialisinginthissortofscenario,withabunchoftechiesstillaroundwhocanstaycurrentwiththelatestwithoutforgettingthe(basicsofthe)past,therewillbelotsofworkforthenext10years."
whilstforOracleinparticular,theeffectsarelikelytoinvolveachangeinbusinessplan
"...Ithinkit’sfairlysafetosaythistoday:
OracleandDB2arelegacydatabases,youdon’tgetfiredcurrentlyfromchoosingSQLServer,andtheopensourcedatabaseswillbecomethedefaultassoonasthey’regoodenough,whichwillhappenrealsoonnow,sincemoreandmoreworktakesplaceoutsidethedatabase,turningthedatabaseintoadatadump.TheopensourcedatabaseswilldotothedatabasemarketwhatLinuxiscurrentlybusydoingintheO/Smarket.Oraclegetsmostofitslicenseprofitsfromthedatabase.Iftheydon’tfindadditionalsourcesofincome(andprofit),suchasPeopleSoft,theywillfailbecauseoftheconstantattackontheirprofitsanctuaries(thedatabaselicencesandSupport).OraclewillbeboughtbyIBMorHPiftheydon’tmanagetogrowtoacomparablesize."
Sowhatdoesthismeanforusthen,whosecareers(presumably)arebasedaroundourknowledgeofOracle?WellIthinkitssafetosaythat,whilstImintotalagreementwithMogensonhisassessmentofthemarket(whichunfortunatelyalwayspickscheapestandsimplestabovecomplexityandcostly)ImsureeveryonewouldagreethattheOracleRDBMSisntgoinganywhereinthenearfuture.IfyouspoketoTomKyte(orindeedMogens)youcouldpointtoanynumberofnewfeaturesthatmakeOraclemorepowerful,easiertoadministerandlesscostlytorun,andnodoubtwhendatabasessuchasSQLServerandmySQLgetthefeaturesthatOraclecurrentlyhas,theyllbejustascomplextoadminister.
However,timeandtimeagainnowIcomeacrosssituationswherethedatabaseisconsideredjustpartoftheunderlyingplatformandalltherealactivitytakesplaceonthemid-tierandintheapplication,andifyouvegoingtodothat,youmightaswellusemySQLorAccess.Also(andthisisparticularlypronouncedintheBIandOLAPworld,andwillbemoresowhenYukoncomesout)rivaldatabasesarecatchingupwithOracleintermsoffeatures,andinmostcaseshaveabetter"outofthebox"experiencethatdoesntscareoffcuriousfirst-timeusersofthedatabase.
Ithinklikeinanywalkoflife,itpaystohedgeyourbets,andifyouspeaktomostadvocatesofOracletechnology(includingmanyoftheOaktablemembers)theyalsohaveagoodunderstandingofrivalRDBMSs,andinsomecasesrecommendtheminpreferencetoOracle.Also,itdependswhereyouareinyourcareer-Im36nowandworkingwithOraclemoreorlessforallofmyITcareer,andinallprobabilitywillcontinuetoworkwithdatabasesfortherestofmytimeintheindustry.If,however,Iwasjuststartingout,IdprobablyfocusmoreonJavaor.NETapplicationcoding,lookmoreat"mid-tier"issuesandspendlesstimeonthedatabase,storageandtheoperatingsystem.Still,havingsaidthat,IstillcomeacrossAS/400-basedapplications,andconsultantswhostillmakeapacketlookingafterthesesupposed"legacy"systems,anddonthavetospendalltheirtimerecertifyingandgettingtheirheadsaroundconceptssuchas"gridcomputing"and"service-orientatedarchitectures",soitcouldjustpaytosititoutandleteveryoneelsefightitoutoverthenextnewgreatthing.
正如前文所提到的，MySQL易学、易部署、易管理和易维护。 分区表是个亮点！从分区表也能看出微软要做大作强SQLServer的信心。资料很多，这里不详细说。但是重点了解的是：现在的SQLServer2005的表，都是默认为分区表的。因为它要支持滑动窗口的这个特性。这种特性对历史数据和实时数据的处理是很有帮助的。 两个月啃那本sqlserver2005技术内部-存储引擎，花了几个月啃四本书 不过话说回来了，绝大多数的性能优化准则与对sqlserver存储的结构理解息息相关 但是随着数据量的增大，这种成本差距会逐渐减小，趋于相等。（500万数量级只相差10%左右） 还不是性能有问题！否则面向对象的数据库早就实现了！建议使用CLR的地方一般是和应用的复杂程度或操作系统环境有很高的耦合度的场景。如你想构建复杂的算法，并且用到了大量的指针和高级数据模型。 我是新手，正在学习数据库和操作系统，深感理论的泛广，唯有一步一步来，但是又感觉时间不够，收集了很多资料却总是没能认真的看完，希望有一个讨论板块，大家共同解决，共同分享，共同努力 你可以简单地认为适合的就是好，不适合就是不好。 不过话说回来了，绝大多数的性能优化准则与对sqlserver存储的结构理解息息相关 SP4是一个累积性的ServicePack，包含自以前的ServicePack发布以来所有的修补程序（包括MS03-031安全公告）。 比如日志传送、比如集群。。。
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