2023年OracleOCP認(rèn)證考試題庫解析

QUESTION1

Younoticethattheperformanceofthedatabasehasdegradedbecauseoffrequentcheckpoints.

Whichtwoactionsresolvetheissue?(Choosetwo.)

A.Disableautomaticcheckpointtuning

B.Checkthesizeoftheredologfilesizeandincreasethesizeifitissmall

C.SettheFAST_START_MTTR_TARGETparameteraspertheadvicegivenbytheMTTRAdvisor

D.Decreasethenumberofredologmembersiftherearemorethanoneredologmembersavailableineachredologgroup

CorrectAnswer:BC

Explanation/Reference:

檢查點進(jìn)程:

Thecheckpointprocess(CKPT)updatesthecontrolfileanddatafileheaderswithcheckpointinformationandsignalsDBWntowriteblockstodisk.Checkpointinformationincludesthecheckpointposition,SCN,locationinonlineredologtobeginrecovery,andsoon.CKPTdoesnotwritedatablockstodatafilesorredoblockstoonlineredologfiles.

檢查點作用:

(1)定期促進(jìn)DBWn進(jìn)程把內(nèi)存的臟塊寫回到數(shù)據(jù)文件,數(shù)據(jù)庫故障時不會丟數(shù)據(jù)

(2)削減實例恢復(fù)的時間

(3)確保全部已提交的數(shù)據(jù)在全都性關(guān)閉期間會被寫入數(shù)據(jù)文件

實例恢復(fù)時間:

指的是將數(shù)據(jù)文件的最終一個檢查點(檢查點位置)推動到掌握文件中記錄的最新SCN所需的時間.治理員可以通過設(shè)置MTTR目標(biāo)以及調(diào)整重做日志組的大小來掌握該時間.

MTTR:

MeanTimeToRepair,即平均修復(fù)時間.是指可修復(fù)產(chǎn)品的平均修復(fù)時間,就是從消失故障到修復(fù)中間的這段時間.MTTR越短表示易恢復(fù)性越好.在數(shù)據(jù)庫中可以通過設(shè)置參數(shù)FAST_START_MTTR_TARGET(單位為秒),掌握數(shù)據(jù)庫對單個實例執(zhí)行崩潰恢復(fù)所花費的時間.

FAST_START_MTTR_TARGE=非0值,啟用快速啟動檢查點功能,自動掌握發(fā)檢查點速度.

FAST_START_MTTR_TARGE=0,禁用快速啟動檢查點功能.

假如重做日志文件的size太小,會頻繁切換日志,即會頻繁發(fā)生檢查點,故可以增大重做日志文件的size削減檢查點發(fā)生頻率.

FAST_START_MTTR_TARGET假如設(shè)置的太小,為了要掌握數(shù)據(jù)庫單實例的實例恢復(fù)時間，則必需頻繁發(fā)生檢查點,確保內(nèi)存中已修改的數(shù)據(jù)塊能夠定期寫入到磁盤,故可以使用MTTRAdvisor來設(shè)置推舉的值.

QUESTION2

Identifythememorycomponentfromwhichmemorymaybeallocatedfor:Sessionmemoryforthesharedserver,BuffersforI/OslavesOracleDatabaseRecoveryManager(RMAN)backupandrestoreoperations

A.LargePool

B.RedoLogBuffer

C.DatabaseBufferCache

D.ProgramGlobalArea(PGA)

CorrectAnswer:A

Explanation/Reference:

LargePool

Thelargepoolisanoptionalmemoryareaintendedformemoryallocationsthatarelargerthanisappropriateforthesharedpool.Thelargepoolcanprovidelargememoryallocationsforthefollowing:

UGAforthesharedserverandtheOracleXAinterface(usedwheretransactionsinteractwithmultipledatabases)

Messagebuffersusedintheparallelexecutionofstatements

BuffersforRecoveryManager(RMAN)I/Oslaves

ByallocatingsessionmemoryfromthelargepoolforsharedSQL,thedatabaseavoidsperformanceoverheadcausedbyshrinkingthesharedSQLcache.ByallocatingmemoryinlargebuffersforRMANoperations,I/Oserverprocesses,andparallelbuffers,thelargepoolcansatisfylargememoryrequestsbetterthanthesharedpool.

QUESTION3

YouexecutedthefollowingcommandtocreateatablespacecalledSALES_DATA:

SQLCREATETABLESPACEsales_data

DATAFILESIZE100M

SEGMENTSPACEMANAGEMENTAUTO;

WhichtwostatementsaretrueabouttheSALES_DATAtablespace?(Choosetwo)

A.Thedatabaseautomaticallydeterminestheextent-sizingpolicyforthetablespace.

B.Thesegmentsareautomaticallyshrunkwhenthecontentsareremovedfromthem.

C.Theallocationofextentswithinthetablespaceismanagedthroughthedictionarytables.

D.Thespaceutilizationdescriptionofthedatablocksinsegmentsisrecordedinbitmapblocks.

E.Thespaceutilizationdescriptionofthedatablocksinsegmentsismanagedthroughfreelists.

CorrectAnswer:AD

Explanation/Reference:

段空間治理:本地治理的表空間中的.段空間治理方式可指定為:

自動:OracleDB使用位圖治理段中的空閑空間.位圖描述了段中每個數(shù)據(jù)塊的狀態(tài),該狀態(tài)與可插入行的塊中的空間量有關(guān).當(dāng)數(shù)據(jù)塊中可用空間增多或削減時,位圖中會反映數(shù)據(jù)塊的新狀態(tài).通過使用位圖,OracleDB可以提高治理空閑空間的自動化程度.因此,這種空間治理方式稱為自動段空間治理(ASSM).

手動:此方法指定要使用空閑列表來治理段中的空閑空間.空閑列表是由一些數(shù)據(jù)塊組成的列表,這些數(shù)據(jù)塊中有可插入行的空間.由于這種治理段空間的方式需要為在表空間中創(chuàng)立的方案對象指定并優(yōu)化PCTUSED、FREELISTS和FREELISTGROUPS存儲參數(shù),因此這種方式稱為手動段空間治理.支持使用此方法是為了向后兼容,建議使用ASSM.

可通過dba_tablespaces查看分區(qū)和段空間治理方式:

SYS@ENMOEDUselecttablespace_name,extent_management,segment_space_managementfromdba_tablespaces;

TABLESPACE_NAMEEXTENT_MANSEGMEN

--------------------------------

SYSTEMLOCALMANUAL

SYSAUXLOCALAUTO

TEMPLOCALMANUAL

USERSLOCALAUTO

EXAMPLELOCALAUTO

UNDOTBS1LOCALMANUAL

QUESTION4

InwhichofthescenariowilltheDBAperformrecovery?(Chooseallthatapply.)

A.Thealertlogfileiscorrupted

B.Atablespaceisaccidentallydropped

C.Oneoftheredologmembersiscorrupted

D.Adatabaseuserterminatesthesessionabnormally

E.Theharddiskonwhichthedatafilesisstorediscorrupted

CorrectAnswer:BE

Explanation/Reference:

DBA一般在數(shù)據(jù)庫消失