oracle体系结构

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1、OracleArchitecturalComponents网络通讯室王鹏飞ObjectivesAftercompletingthislesson,youshouldbeabletodothefollowing:OutlinetheOraclearchitectureanditsmaincomponentsListthestructuresinvolvedinconnectingausertoanOracleinstanceOverviewofPrimaryComponentsInstanceSGARedologbuffercacheSharedpoolDataDi

2、ct.cacheLibrarycacheDBWRSMONPMONCKPTLGWROthersUserprocessServerprocessPGAControlfilesDatafilesArchivedlogfilesParameterfilePasswordfileRedologfilesDatabaseDatabasebuffercacheOracleServerAnOracleserver:Isadatabasemanagementsystemthatprovidesanopen,comprehensive,integratedapproachtoinfo

3、rmationmanagementConsistsofanOracleinstanceandanOracledatabaseOracleServerOracleInstanceAnOracleinstance:IsameanstoaccessanOracledatabaseAlwaysopensoneandonlyonedatabaseConsistsofmemoryandprocessstructuresEstablishingaConnectionandCreatingaSessionConnectingtoanOracleinstanceconsistsof

4、establishingauserconnectionandcreatingasession.ConnectionestablishedSessioncreatedDatabaseuserUserprocessOracleserverServerprocessOracleDatabaseAnOracledatabase:IsacollectionofdatathatistreatedasaunitConsistsofthreefiletypesControlfilesDatafilesArchivedlogfilesParameterfilePasswordfil

5、eRedologfilesOracleDatabasePhysicalStructureThephysicalstructureofanOracledatabaseisdeterminedbytheoperatingsystemfilesthatprovidetheactualphysicalstoragefordatabaseinformation.ControlfilesDatafilesRedologfilesControlfilesDatafiles(includesdatadictionary)HeaderOnlineredologfiles)Memor

6、yStructureOracle’smemorystructureconsistsoftwomemoryareasknownas:SystemGlobalArea(SGA):Allocatedatinstancestartup,andisafundamentalcomponentofanOracleInstanceProgramGlobalArea(PGA):AllocatedwhentheserverprocessisstartedSystemGlobalArea(SGA)TheSGAconsistsofseveralmemorystructures:Share

7、dpoolDatabasebuffercacheRedologbufferOtherstructures(e.g.lockandlatchmanagement,statisticaldata)TherearetwooptionalmemorystructuresthatcanbeconfiguredwithintheSGA:LargepoolJavapoolSystemGlobalArea(SGA)SGAisdynamicandsizedusingSGA_MAX_SIZE.SGAmemoryallocatedandtrackedingranulesbySGAcom

8、ponen