3-2.模式对象管理(索引)

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1、SRC:Oracle8iAdministrator’sGuide(14)ManagingIndexes·GuidelinesforManagingIndexes·CreatingIndexes·AlteringIndexes·MonitoringSpaceUseofIndexes·DroppingIndexesGuidelinesforManagingIndexeslOracleprovidesseveralindexingschemes:lB*-treeindexes(currentlythemostcommon)lB*-treeclusterindexeslhashclu

2、sterindexeslreversekeyindexeslbitmapindexeslfunction-basedindexesldomainindexeslIndexesarelogicallyandphysicallyindependentofthedataintheassociatedtable.lOracleautomaticallyreflectschangestodata,suchasaddingnewrows,updatingrows,ordeletingrows,inallrelevantindexeswithnoadditionalactionbyuser

3、s.CreateIndexesAfterInsertingTableDatalYoushouldcreateanindexforatableafterinsertingorloadingdata(viaSQL*LoaderorImport)intothetable.lItismoreefficienttoinsertrowsofdataintoatablethathasnoindexesandthencreatetheindexesforsubsequentaccess.lYoumustalsocreatetheindexforaclusterbeforeinsertinga

4、nydataintothecluster.lIftheindexisextremelylarge,youmaywanttoperformthefollowingtasks.lToManageaLargeIndex:1.Createanewtemporarysegmenttablespace.2.Altertheindexcreator’stemporarysegmenttablespace.3.Createtheindex.4.Removethetemporarysegmenttablespaceandre-specifythe8creator’stemporarysegme

5、nttablespace,ifdesired.1.LimittheNumberofIndexesperTablelThereisatrade-offbetweenthespeedofretrievingdatafromatableandthespeedofupdatingthetable.SpecifyTransactionEntryParameterslByspecifyingtheINITRANSandMAXTRANSparametersduringthecreationofeachindex,youcanaffecthowmuchspaceisinitiallyandc

6、aneverbeallocatedfortransactionentriesinthedatablocksofanindex’ssegment.SpecifyIndexBlockSpaceUselWhenanindexiscreatedforatable,datablocksoftheindexarefilledwiththeexistingvaluesinthetableuptoPCTFREE.EstimateIndexSizeandSetStorageParameterslThemaximumsizeofasingleindexentryisapproximatelyon

7、e-halfthedatablocksize.Aswithtables,youcanexplicitlysetstorageparameterswhencreatinganindex.SpecifytheTablespaceforEachIndexlIndexescanbecreatedinanytablespace.Anindexcanbecreatedinthesameordifferenttablespaceasthetableitindexes.lIfyouusedifferenttablesp