吉林大学大型数据库设计与实现dba-05.ppt

DataDictionaryContentsandUsage

ObjectivesAftercompletingthislesson,youshouldbeabletodothefollowing:IdentifykeydatadictionarycomponentsIdentifythecontentsandusesofthedatadictionaryQuerythedatadictionary

ControlfilesDatafilesRedologfilesDatabaseDataDictionaryDuringdatabasecreation,theOracleservercreatesadditionalobjectstructureswithinthedatafiles.DatadictionarytablesDynamicperformancetablesDataDictionaryTablesDynamicPerformanceTables

DataDictionaryThedatadictionaryisasetofread-onlytablesandviewsthatrecord,verify,andprovideinformationaboutitsassociateddatabase.DescribesthedatabaseanditsobjectsIncludestwotypesofobjects:BasetablesStoredescriptionofdatabaseCreatedwithCREATEDATABASEDataDictionaryviewsSummarizebasetableinformationCreatedusingcatalog.sqlscript

DataDictionaryContentsThedatadictionaryprovidesinformationabout:LogicalandphysicaldatabasestructureDefinitionsandspaceallocationsofobjectsIntegrityconstraintsUsersRolesPrivilegesAuditing

HowtheDataDictionaryIsUsedThedatadictionaryhasthreeprimaryuses:TheOracleserverusesittofindinformationabout:UsersSchemaobjectsStoragestructuresTheOracleservermodifiesitwhenaDDLstatementisexecuted.UsersandDBAscanuseitasaread-onlyreferenceforinformationaboutthedatabase.

DataDictionaryViewCategoriesThedatadictionaryconsistsofthreemainsetsofstaticviewsdistinguishedfromeachotherbytheirscope:DBA:WhatisinalltheschemasALL:WhattheusercanaccessUSER:WhatisintheusersschemaDBA_xxxUSER_xxxALL_xxxObjectsownedbythecurrentuserObjectsaccessiblebythecurrentuserAlloftheobjectsinthedatabase

FullNotesPageforPractices

DynamicPerformanceTablesDynamicperformanceviewsrecordcurrentdatabaseactivity.ViewsarecontinuallyupdatedwhilethedatabaseisoperationalInformationisaccessedfrom:MemoryControlfileDBAusesdynamicviews