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1、buffercache的调整与优化（二）（缓冲区缓存的调整与优化（二））AdjustmentandoptimizationofBuffercache(two)Personalclassification:OraclePerformanceTuningAdjustmentandoptimizationofBuffercache(two)Classification:Oracleperformanceoptimizationsixslzsixsixslzslzsixsixslzsixsixsixsixsixsixsixsixsixsixsi
2、xsixsixsixsixsixzixzixzixzixzixzixzix✓Tx✓Txzixzixzixzix✓Tx✓Tx✓Tx✓Tx✓Tx✓Tx✓Tx✓Tx✓Tx✓TxAdjustmentandoptimizationofBuffercache(two)_sixsixsixsixsixsixsixslzsixxixzixxixzixzixzixzixztxztxztxztxBuffercacheisactuallysubdividedintoseveraldifferentBuffercache,suchaskeeppool,recy
3、clepool,defaultpool,andthefollowingdescribestheuseofdifferentbuffercache・AgeneraldescriptionaboutBuffercache,pleasereferto:theadjustmentandoptimizationofBuffercache(a)First,theapplicationofdifferentbufferpoolAbufferpoolcorrespondstoaOracledatablock,andthethreedifferentpo
4、olareactuallydifferentdegreesofaccesstoblocksindatabuffercacheTheusualmethod.Thehottestblocks,hotandcoldstorage,blocktodifferentbufferpool.Infact,severaldifferentbufferpoolindifferentsizedistributionInaddition,thealgorithmsadoptedareallLRUalgorithms,sotheblockcacheandage
5、doutalgorithmareessentiallythesame.Anydifferentbufferpoolwillcacheonlythereaddatablockaccordingtotheaccessmode,thatis,ifalltablesarescanned,allblocksarecached,iftheindexisfastScanning,thecacheindexofallleafnodesblock・Keepbuffercache-poolcorrespondingtokeepRecyclebufferca
6、che-poolcorrespondingtorecycleNKbuffercaches,correspondingtodb_nk_cache_sizeDefaultbuffercache-poolcorrespondingtodafaultKeeppool:Forthesmalltablewilloftenvisititspermanentmemory,thatisplacedintothekeeppool.Itsroleistoensurethatthispartofthedataaccessoftencannotbereplace
7、dbypermanentmemoryandmemory,Thusincreasingthespeedofaccessingthesedata・Thispoolisbestabletomaintaina99%hitrate,thatistosay,toensurethatthesizeofthepoolcancachemostoftheobjectsthatareplacedinthepool.Recyclepool:Forlargesegmentthatisnotfrequentlyaccessed,youcanconsiderplac
8、ingitinrecyclepooltoeliminateitassoonaspossible・Dafaultpool:Thebufferpoolofordinaryobjects,thosethatare
