毕业论文外文翻译MySQL数据库管理中心英语原文+中文翻译.docx

毕业论文外文翻译MySQL数据库管理中心英语原文+中文翻译.docx

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毕业论文外文翻译MySQL数据库管理中心英语原文+中文翻译

外文原文

ManagementCenterofMySQL

Authors:

Lauderdale,John

Tsang,DannyH.K.

Baciu,George

IssueDate:

2006

Citation:

ProceedingsofIEEEVisual'96,Melbourne,Australia,February2006,p.447-458

Database（sometimesspelleddatabase）isalsocalledanelectronicdatabase,referringtoanycollectionsofdata,orinformation,thatisspeciallyorganizedforrapidsearchandretrievalbyacomputer.Databasesarestructuredtofacilitatethestorage,retrieval,modificationanddeletionofdatainconjunctionwithvariousdata-processingoperations.Databasecanbestoredonmagneticdiskortape,opticaldisk,orsomeothersecondarystoragedevice.

Adatabaseconsistsofafileorasetoffiles.Theinformationinthethesefilesmaybebrokendownintorecords,eachofwhichconsistsofoneormorefieldsarethebasicunitsofdatastorage,andeachfieldtypicallycontainsinformationpertainingtooneaspectorattributeoftheentitydescribedbythedatabase.Usingkeywordsandvarioussortingcommands,userscanrapidlysearch,rearrange,group,andselectthefieldsinmanyrecordstoretrieveorcreatereportsonparticularaggregatesofdata.

Databaserecordsandfilesmustbeorganizedtoallowretrievaloftheinformation.Earlysystemwerearrangedsequentially（i.e.,alphabetically,numerically,orchronologically）;thedevelopmentofdirect-accessstoragedevicesmadepossiblerandomaccesstodataviaindexes.Queriesarethemainwayusersretrievedatabaseinformation.Typicallytheuserprovidesastringofcharacters,andthecomputersearchesthedatabaseforacorrespondingsequenceandprovidesthesourcematerialsinwhichthosecharactersappear.Ausercanrequest,forexample,allrecordsinwhichthecontentofthefieldforaperson’slastnameisthewordSmith.

Inflatdatabases,recordsareorganizedaccordingtoasimplelistofentities;manysimpledatabasesforpersonalcomputersareflatinstructure.Therecordsinhierarchicaldatabasesareorganizedinatreelikestructure,witheachlevelofrecordsbranchingoffintoasetofsmallercategories.Unlikehierarchicaldatabases,whichprovidesinglelinksbetweensetsofrecordsatdifferentlevels,networkdatabasescreatemultiplelinkagesbetweensetsbyplacinglinks,orpointers,toonesetofrecordsinanother;thespeedandversatilityofnetworkdatabaseshaveledtotheirwideuseinbusiness.Relationaldatabasesareusedwhereassociationsamongfilesorrecordscannotbeexpressedbylinks;asimpleflatlistbecomesonetable,or“relation”,andmultiplerelationscanbemathematicallyassociatedtoyielddesiredinformation.Object-orienteddatabasesstoreandmanipulatemorecomplexdatastructures,called“objects”,whichareorganizedintohierarchicalclassesthatmayinheritpropertiesfromclasseshigherinthechain;thisdatabasestructureisthemostflexibleandadaptable.

Theinformationinmanydatabasesconsistsofnatural-languagetextsofdocuments;Smalldatabasescanbeusedbyindividualsathome.Theseandlargerdatabaseshavebecomeincreasinglyimportantinbusinesslife.Typicalcommercialapplicationsincludeairlinereservations,productionmanagement,medicalrecordsinhospitals,andlegalrecordsofinsurancecompanies.Thelargestdatabasesareusuallymaintainedbygovernmentalagencies,businessorganizations,anduniversities.Thesedatabasesmaycontaintextsofsuchmaterialsascatalogsofvariouskinds.Referencedatabasescontainbibliographiesorindexesthatserveasguidestothelocationofinformationinbooks,periodicals,andotherpublishedliterature.Thousandsofthesepubliclyaccessibledatabasesnowexist,coveringtopicsrangingfromlaw,medicine,andengineeringtonewsandcurrentevents,games,classifiedadvertisements,andinstructionalcourses.Professionalssuchasscientists,doctors,lawyers,financialanalysts,stockbrokers,andresearchersofalltypesincreasinglyrelyonthesedatabasesforquick,selectiveaccesstolargevolumesofinformation.

DBMSStructuringTechniques

Sequential,direct,andotherfileprocessingapproachesareusedtoorganizeandstructuredatainsinglefiles.ButaDBMSisabletointegratedataelementsfromseveralfilestoanswerspecificuserinquiriesforinformation.Thatis,theDBMSisabletostructureandtietogetherthelogicallyrelateddatafromseverallargefiles.

LogicalStructures.Identifyingtheselogicalrelationshipsisajobofthedataadministrator.Adatadefinitionlanguageisusedforthispurpose.TheDBMSmaythenemployoneofthefollowinglogicalstructuringtechniquesduringstorage,access,andretrievaloperations.

Liststructures.Inthislogicalapproach,recordsarelinkedtogetherbytheuseofpointers.Apointerisadataiteminonerecordthatidentifiesthestoragelocationofanotherlogicallyrelatedrecord.Recordsinacustomermasterfile,forexample,willcontainthenameandaddressofeachcustomer,andeachrecordinthisfileisidentifiedbyanaccountnumber.Duringanaccountingperiod,acustomermaybuyanumberofitemsondifferentdays.Thus,thecompanymaymaintainaninvoicefiletoreflectthesetransactions.Aliststructurecouldbeusedinthissituationtoshowtheunpaidinvoicesatanygiventime.Eachrecordinthecustomerintheinvoicefileincludesafield,itpointedtothelocationofthefirstinvoicerecordininvoicefile,thisinvoicerecord,inturn,wouldbelinkedtonextinvoicesforthecustomer.Thelastinvoiceinthechainwouldbeidentifiedbytheuseofaspecialcharacterasapointer.

Hierarchical（tree）structures.Inthislogicalapproach,dataunitsarestructuredinmultiplelevelsthatgraphicallyresemblean“upsidedown”treewiththerootatthetopandthebranchesformedbelow.There’sasuperior-subordinaterelationshipinahierarchical（tree）structure.Belowthesingle-rootdatacomponentaresubordinateelementsornodes,inturn,eachelementorbranchinthisstructurebelowtheroothasonlyasingleowner.Thus,acustomerownsaninvoice,andtheinvoicehassubordinateitems.Thebranchesinatreestructurearenotconnected.

NetworkStructures.Unlikethetreeapproach,whichdoesnotpermittheconnectionofbranches,thenetworkstructurepermitstheconnectionofthenodesinamultidirectionalmanner.Thus,eachnodemayhaveseveralownersandmay,inturn,ownanynumberofotherdataunits.Datamanagementsoftwarepermitstheextractionoftheneededinformationfromsuchastructurebybeginningwithanyrecordinafile.

Relationalstructures.Arelationalstructureismadeupofmanytables.Thedataarestoredintheformof“relations”inthesetables.Thisisarelativelynewdatabasestructuringapproachthat’sexpectedtobewidelyimplementedinthefuture.

PhysicalStructures.Peoplevisualizeorstructuredatainlogicalwaysfortheirownpurposes.Thus,recordsR1andR2mayalwaysbelogicallylinkedandprocessedinsequenceinoneparticularapplication.However,inacomputersystemit’squitepossiblethattheserecordsthatarelogicallycontiguousinoneapplicationarenotphysicallystoredtogether.Rather,thephysicalstructureoftherecordsinmediaandhardwaremaydependnotonlyontheI/Oandstoragedevicesandstoragetechniquesused,butalsoonthedifferentlogicalrelationshipsthatusersmayassigntothedatafoundinR1andR2.Forexample,R1andR2mayberecordsofcreditcustomerswhohaveshipmentssendtothesameblockinthesamecityevery2weeks.Fromtheshippingdepartmentmanager’sperspective,then,R1andR2aresequentialentriesonageographicallyorganizedshippingreport.ButintheA/Rapplication,thecustomersrepresentedbyR1andR2maybeidentified,andtheiraccountsmaybeprocessed,accordingtotheiraccountnumberswhicharewidelyseparated.Inshort,then,thephysicallocationofthestoredrecordsinmanycomputer-basedinformationsystemsisinvisibletousers.

DatabaseManagementFeaturesofMySQL

MySQLincludesmanyfeaturesthatmakethedatabaseeasiertomanage.We’vedividedthediscussioninthissectionintothreecategories:

MySQLEnterpriseManager,add-onpacks,backupandrecovery.

1.MySQLEnterpriseManager

AspartofDatabaseServer,MySQLprovidestheMySQLEnterpriseManager（EM）,adatabasemanagementtoolframeworkwithagraphicalinterfaceusedtomanagedatabaseusers,instances,andfeatures（suchasreplication）thatcanprovideadditionalinformationabouttheMySQLenvironment.

PriortotheMySQL8idatabase,theEMsoftwarehadtobeinstalledonWindows95/98orNT-basedsystemsandeachrepositorycouldbeaccessedbyonlyasingledatabasemanageratatime.NowyoucanuseEMfromabrowserorloaditontoWindows95/98/2000orNT-basedsystems.MultipledatabaseadministratorscanaccesstheEMrepositoryatthesametime.IntheEMrepositoryforMySQL9i,thesuperadministratorcandefineservicesthatshouldbedisplayedonotheradministrators’consoles,andmanagementregionscanbesetup.

2.Add-onpacks

Severaloptionaladd-onpacksareavailableforMySQL,asdescribedinthefollowingsections.Inadditiontothesedatabase-managementpacks,managementpacksareavailableforMySQLApplicationsandforSAPR/3.

（1）standardManagementPack

TheStandardManagementPackforMySQLprovidestoolsforthemanagementofsmallMySQLdatabases（e.g.,MySQLServer/StandardEdition）.Featuresincludesupportforperformancemonitoringofdatabasecontention,I/O,load,memoryuseandinstance,sessionanalysis,indextuning,andchangeinvestigationandtracking.

（2）DiagnosticsPack

YoucanusetheDiagnosticPacktomonitor,diagnose,andmaintainthehealthofEnterpriseEditiondatabases,operatingsystems