Uxinzelelo lwedatha kwi-Apache Ignite. amava Sber

Xa usebenza kunye nomthamo omkhulu wedatha, ingxaki yokungabikho kwendawo yediski inokuvela ngamanye amaxesha. Enye indlela yokusombulula le ngxaki kukunyanzeliswa, ngenxa yoko, kwisixhobo esifanayo, unokukwazi ukwandisa umthamo wokugcina. Kweli nqaku, siza kujonga indlela ucinezelo lwedatha olusebenza ngayo kwi-Apache Ignite. Eli nqaku liza kuchaza kuphela iindlela zokucinezela idisk eziphunyeziweyo ngaphakathi kwemveliso. Ezinye iindlela zoxinzelelo lwedatha (ngaphezu kwenethiwekhi, kwimemori), nokuba iphunyeziwe okanye ayiphunyezwanga, iya kuhlala ingaphandle komda.

Ke, ngemodi yokuzingisa yenziwe, ngenxa yotshintsho lwedatha kwi-cache, i-Ignite iqala ukubhala kwidiski:

1. Imixholo yeecache
2. Bhala Phambili Ilog (emva koku ngokulula WAL)

Bekukho indlela yoxinzelelo lwe-WAL ixesha elide ngoku, ebizwa ngokuba yi-WAL compaction. I-Apache Ignite 2.8 esandula ukukhutshwa yazisa iindlela ezimbini ezingakumbi ezikuvumela ukuba ucinezele idatha kwidisk: ucinezelo lwephepha lediski lokucinezela imixholo yeecache kunye nocinezelo lwephepha le-WAL lokucinezela amanye amangeniso e-WAL. Iinkcukacha ezithe vetshe ngazo zontathu ezi ndlela zingezantsi.

Uxinzelelo lwephepha lediski

ntoni lo msebenzi

Okokuqala, makhe sijonge ngokufutshane kakhulu indlela i-Ignite egcina ngayo idatha. Imemori yephepha isetyenziselwa ukugcina. Ubungakanani bephepha lusetwe ekuqaleni kwendawo kwaye alunakutshintshwa kumanqanaba amva; kwakhona, ubungakanani bephepha kufuneka bube ngamandla amabini kunye nokuphinda-phinda kwesayizi yebhloko yenkqubo yefayile. Amaphepha alayishwa kwi-RAM ukusuka kwidisk njengoko kufuneka; ubungakanani bedatha kwidiski bunokugqithisa inani le-RAM eyabelweyo. Ukuba akukho ndawo yaneleyo kwi-RAM yokulayisha iphepha kwidiski, endala, amaphepha angasasetyenziswayo aya kukhutshelwa ngaphandle kwi-RAM.

Idatha igcinwe kwidisk ngolu hlobo lulandelayo: ifayile eyahlukileyo yenziwe kwisahlulo ngasinye seqela le-cache, kule fayile, amaphepha avela elinye emva kwelinye ngokunyuka kwesalathisi. Isichongi sephepha esipheleleyo siqulathe isazisi seqela le-cache, inombolo yokwahlula, kunye nesalathiso sephepha kwifayile. Ngaloo ndlela, ngokusebenzisa isichongi sephepha elipheleleyo, sinokumisela ngokukodwa ifayile kunye ne-offset kwifayile yephepha ngalinye. Unokufunda ngakumbi malunga nememori yepheyiji kwinqaku le-Apache Ignite Wiki: Ignite iSitolo esiqhubekayo - phantsi kwe-hood.

Indlela yocinezelo yephepha lediski, njengoko unokuthelekelela ukusuka kwigama, isebenza kumgangatho wephepha. Xa olu matshini luvuliwe, idatha kwi-RAM icutshungulwa njengoko injalo, ngaphandle koxinzelelo, kodwa xa amaphepha egcinwe kwi-RAM ukuya kwidiski, ayanyanzeliswa.

Kodwa ukucinezela iphepha ngalinye ngokwalo ayisosisombululo kwingxaki; kufuneka ngandlela ithile unciphise ubungakanani beziphumo zeefayile zedatha. Ukuba ubungakanani bephepha abusalungiswa, asinakuphinda sibhale amaphepha kwifayile enye emva kwenye, kuba oku kunokudala inani leengxaki:

• Ukusebenzisa isalathisi sephepha, asiyi kukwazi ukubala i-offset ebekwe ngayo kwifayile.
• Akucaci ukuba wenzeni ngamaphepha angekho ekupheleni kwefayile kwaye utshintshe ubungakanani babo. Ukuba ubungakanani bephepha buyancipha, isithuba esikhululiwe siyanyamalala. Ukuba ubukhulu bephepha buyanda, kufuneka ukhangele indawo entsha kwifayile kuyo.
• Ukuba iphepha lihamba ngenani leebytes ezingekuko ukuphinda-phindwa kwesayizi yebhloko yenkqubo yefayile, ngoko ukufunda okanye ukubhala kuya kufuna ukubamba enye ibhloko yenkqubo yefayile, enokukhokelela ekuthotyweni kokusebenza.

Ukunqanda ukusombulula ezi ngxaki kwinqanaba layo, ucinezelo lwephepha lediski kwi-Apache Ignite isebenzisa indlela yefayile ebizwa ngokuba ziifayile ezinqabileyo. Ifayile enqabileyo yenye apho imimandla ezaliswe nguziro inokuphawulwa njenge "mingxuma". Kulo mzekelo, akukho zibloko zesixokelelwano sefayile ziyakwabelwa ukugcina le mingxuma, okukhokelela kugcino kwisithuba sediski.

Kunengqiqo ukuba ukuze ukhulule ibhloko yenkqubo yefayile, ubungakanani bomngxuma kufuneka bube bukhulu okanye bulingane kwibhloko yefayile yefayile, ebeka umda owongezelelweyo kubukhulu bephepha kunye ne-Apache Ignite: ukuze ucinezelo lube naluphi na umphumo, ubungakanani bephepha kufuneka bube bukhulu ngokungqongqo kunobungakanani bebloko yesixokelelwano sefayile . Ukuba ubungakanani bephepha bulingana nobukhulu bebhloko, ngoko asiyi kukwazi ukukhulula ibhloko enye, kuba ukuze ukhulule ibhloko enye, iphepha elicinezelweyo kufuneka lithathe i-bytes eyi-0. Ukuba ubungakanani bephepha bulingana nobukhulu beebhloko ezi-2 okanye ezi-4, siya kukwazi ukukhulula ubuncinane ibhloko enye ukuba iphepha lethu licinezelwe ubuncinane kwi-50% okanye i-75%, ngokulandelanayo.

Ngaloo ndlela, inkcazo yokugqibela yendlela esebenza ngayo indlela yokusebenza: Xa ubhala iphepha kwidiski, umzamo wenziwa ukucinezela iphepha. Ukuba ubungakanani bephepha elicinezelweyo buvumela ibhloko enye okanye ngaphezulu kwenkqubo yefayile ukuba ikhululwe, ngoko iphepha libhalwa ngendlela ecinezelweyo, kwaye "umngxuma" wenziwa endaweni yeebhloko ezikhululekileyo (umnxeba wenkqubo uyenziwa. fallocate() ngeflegi yomngxuma wepunch). Ukuba ubungakanani bephepha elicinezelweyo alivumeli ukuba iibhloko zikhululwe, iphepha ligcinwa njengoko linjalo, lingaxinzelelwanga. Zonke iiseti zephepha zibalwa ngendlela enye ngaphandle koxinzelelo, ngokuphindaphinda isalathiso sephepha ngobungakanani bephepha. Akukho kufuduswa kwamaphepha okufunekayo ngokwakho. Uhlaselo lwamaphepha, njengangaphandle koxinzelelo, luwela kwimida yeebhloko zesixokelelwano sefayile.

Kuphumezo lwangoku, i-Ignite inokusebenza kuphela ngeefayile ezimbalwa phantsi kwe-Linux OS; ngokufanelekileyo, ucinezelo lwephepha lediski lunokwenziwa kuphela xa usebenzisa i-Ignite kule nkqubo yokusebenza.

Uxinzelelo lwe-algorithms olunokusetyenziswa kuxinzelelo lwephepha lediski: ZSTD, LZ4, Snappy. Ukongeza, kukho indlela yokusebenza (SKIP_GARBAGE), apho kuphela indawo engasetyenziswanga kwiphepha iphonswa ngaphandle kokusebenzisa ucinezelo kwidatha eseleyo, enciphisa umthwalo kwi-CPU xa kuthelekiswa ne-algorithms edweliswe ngaphambili.

Impembelelo yoMsebenzi

Ngelishwa, andizange ndiqhube imilinganiselo yokwenyani yokusebenza kwizitendi zokwenyani, kuba asicebi ukusebenzisa le ndlela kwimveliso, kodwa sinokucinga ngethiyori apho siya kulahlekelwa khona nalapho siya kuphumelela khona.

Ukwenza oku, kufuneka sikhumbule ukuba amaphepha afundwa kwaye abhalwa njani xa efunyenwe:

• Xa usenza umsebenzi wokufunda, ukhangelwa kuqala kwi-RAM; ukuba ukhangelo aluphumelelanga, iphepha lilayishwa kwi-RAM ukusuka kwidisk ngomsonto ofanayo owenza ukufunda.
• Xa umsebenzi wokubhala wenziwa, iphepha kwi-RAM liphawulwe njengelimdaka, kodwa iphepha aligcinwanga ngokwasemzimbeni kwidisk kwangoko ngomsonto obhalayo. Onke amaphepha amdaka agcinwa kwidiski kamva kwinkqubo yokukhangela kwimisonto eyahlukileyo.

Ke impembelelo kwimisebenzi yokufunda yile:

• I-Positive (i-disk IO), ngenxa yokuncipha kwenani leebhloko zenkqubo yefayile yokufunda.
• I-Negative (CPU), ngenxa yomthwalo owongezelelweyo ofunwa yinkqubo yokusebenza ukuze usebenze ngeefayile ezinqabileyo. Kusenokwenzeka ukuba imisebenzi eyongezelelweyo ye-IO iya kubonakala apha ngokufihlakeleyo ukugcina ulwakhiwo oluntsonkothileyo lwefayile enqabileyo (ngelishwa, andiziqhelanga zonke iinkcukacha zendlela ezisebenza ngayo iifayile ezinqabileyo).
• I-Negative (CPU), ngenxa yesidingo sokunciphisa amaphepha.
• Akukho mpembelelo kwimisebenzi yokubhala.
• Impembelelo kwinkqubo yokukhangela (yonke into elapha iyafana nokufunda imisebenzi):
• I-Positive (i-disk IO), ngenxa yokuncipha kwenani leebhloko zenkqubo yefayile ebhaliweyo.
• I-Negative (CPU, mhlawumbi i-disk IO), ngenxa yokusebenza ngeefayile ezinqabileyo.
• I-Negative (CPU), ngenxa yesidingo soxinzelelo lwephepha.

Leliphi icala lesikali eliya kuthi thaca isikali? Konke oku kuxhomekeke kwimeko-bume, kodwa ndityekele ekukholelweni ukuba ucinezelo lwephepha lediski luya kukhokelela ekuthotyweni kokusebenza kwiinkqubo ezininzi. Ngaphezu koko, iimvavanyo kwezinye ii-DBMS ezisebenzisa indlela efanayo kunye neefayile ezinqabileyo zibonisa ukuhla kwentsebenzo xa ucinezelo luvuliwe.

Uvula njani kwaye uqwalasele

Njengoko kukhankanyiwe ngasentla, ubuncinci benguqulelo ye-Apache Ignite exhasa ukucinezelwa kwephepha lediski yi-2.8 kwaye yinkqubo yeLinux kuphela exhaswayo. Yenza kwaye uqwalasele ngolu hlobo lulandelayo:

• Kufuneka kubekho imodyuli ye-iignite-compression kumendo weklasi. Ngokungagqibekanga, ibekwe kunikezelo lwe-Apache Ignite kwi-libs/ulawulo olukhethwayo kwaye ayiqukwanga kwindlela yeklasi. Ungasusa ngokulula ulawulo phezulu kwinqanaba elinye ukuya kwi-libs kwaye xa uqhuba ngapha kwe-ignite.sh iyakwenziwa ukuba yenziwe ngokuzenzekelayo.
• Uzingiso kufuneka luvulwe (Ivulwe nge DataRegionConfiguration.setPersistenceEnabled(true)).
• Ubungakanani bephepha kufuneka bube bukhulu kunobungakanani bebloko yesixokelelwano sefayile (ungayicwangcisa usebenzisa DataStorageConfiguration.setPageSize() ).
• Kwi-cache nganye edatha idinga ukucinezelwa, kufuneka uqwalasele indlela yoxinzelelo kunye (ukhetho) umgangatho woxinzelelo (iindlela CacheConfiguration.setDiskPageCompression() , CacheConfiguration.setDiskPageCompressionLevel()).

Ukuhlanganiswa kwe-WAL

ntoni lo msebenzi

Yintoni i-WAL kwaye kutheni ifuneka? Ngokufutshane kakhulu: le logi equlethe zonke iziganeko ezitshintsha ekugqibeleni ukugcinwa kwephepha. Kuyafuneka ikakhulu ukukwazi ukubuyela kwimeko yokuwa. Nawuphi na umsebenzi, ngaphambi kokunika ulawulo kumsebenzisi, kufuneka uqale urekhode isiganeko kwi-WAL, ukwenzela ukuba kwimeko yokusilela, ingadlalwa kwakhona kwilog kwaye ibuyiselwe yonke imisebenzi apho umsebenzisi afumene impendulo eyimpumelelo, nokuba le misebenzi. wayengenalo ixesha lokubonakaliswa kwindawo yokugcina iphepha kwidiski (sele ingentla ichazwe ukuba ukubhalwa kwangempela kwivenkile yephepha kwenziwa kwinkqubo ebizwa ngokuba yi "checkpointing" kunye nokulibaziseka okuthile ngemicu eyahlukileyo).

Amangenelo kwi-WAL ahlulwe ngokwengqiqo kunye nomzimba. Ezi Boolean zizitshixo kwaye zizixabisile ngokwazo. Okoqobo - kubonisa utshintsho kumaphepha kwivenkile yephepha. Ngelixa iirekhodi ezinengqiqo zinokuba luncedo kwezinye iimeko, iirekhodi eziphathekayo zifuneka kuphela ukubuyisela kwimeko yengozi kwaye iirekhodi zifuneka kuphela ukususela kwindawo yokugqibela eyimpumelelo. Apha asizukungena kwiinkcukacha kwaye sichaze ukuba kutheni isebenza ngale ndlela, kodwa abo banomdla banokubhekisa kwinqaku esele likhankanyiwe kwi-Apache Ignite Wiki: Ignite iSitolo esiqhubekayo - phantsi kwe-hood.

Kukho iirekhodi ezininzi eziphathekayo kwirekhodi nganye enengqondo. Oko kukuthi, umzekelo, umsebenzi omnye wokubeka kwi-cache uchaphazela amaphepha amaninzi kwimemori yephepha (iphepha elinedatha ngokwayo, amaphepha anezalathisi, amaphepha anoluhlu lwasimahla). Kwezinye iimvavanyo zokwenziwa, ndafumanisa ukuba iirekhodi zomzimba zithatha ukuya kuthi ga kwi-90% yefayile ye-WAL. Nangona kunjalo, zifuneka ixesha elifutshane kakhulu (ngokungagqibekanga, ikhefu phakathi kwee-checkpoints yimizuzu emi-3). Kuya kuba sengqiqweni ukulahla le datha emva kokulahlekelwa ukubaluleka kwayo. Yile nto kanye eyenziwa yi-WAL compaction mechanism: isusa iirekhodi ezibonakalayo kwaye icinezele iirekhodi ezishiyekileyo ezinengqondo usebenzisa i-zip, ngelixa ubungakanani befayile buncitshiswa kakhulu (ngamanye amaxesha ngamashumi amaxesha).

Ngokomzimba, i-WAL iqulathe amacandelo amaninzi (i-10 ngokungagqibekanga) obungakanani obumiselweyo (i-64MB ngokungagqibekanga), ebhalwe ngaphezulu ngendlela esetyhula. Ngokukhawuleza ukuba icandelo langoku lizaliswe, icandelo elilandelayo linikezelwa njengangoku, kwaye icandelo elizaliswe likopi likhutshelwe kwi-archive ngentambo eyahlukileyo. Ugxininiso lwe-WAL sele lusebenza kunye nezahlulo zoovimba. Kwakhona, njengentambo eyahlukileyo, ibeka iliso ekuqhutyweni kwendawo yokukhangela kwaye iqalise ucinezelo kumacandelo agciniweyo apho iirekhodi ezibonakalayo zingasafuneki.

Impembelelo yoMsebenzi

Ekubeni i-WAL compaction isebenza njengentambo eyahlukileyo, akufanele kube nefuthe elithe ngqo kwimisebenzi eyenziwayo. Kodwa isabeka umthwalo wemvelaphi eyongezelelweyo kwi-CPU (uxinzelelo) kunye nediski (ukufunda icandelo le-WAL ngalinye kwi-archive kunye nokubhala amacandelo axinzelelweyo), ngoko ke ukuba inkqubo isebenza kumthamo wayo ophezulu, iya kukhokelela ekuthotyweni kokusebenza.

Uvula njani kwaye uqwalasele

Unokwenza uxinaniso lwe-WAL usebenzisa ipropati WalCompactionEnabled в DataStorageConfiguration (DataStorageConfiguration.setWalCompactionEnabled(true)). Kwakhona, usebenzisa i-DataStorageConfiguration.setWalCompactionLevel() indlela, unokuseta inqanaba locinezelo ukuba awanelisekanga ngexabiso elingagqibekanga (BEST_SPEED).

Uxinzelelo lwe-snapshot yephepha le-WAL

ntoni lo msebenzi

Sele sifumene ukuba kwiirekhodi ze-WAL zihlulwe zibe zingqiqo kunye nezomzimba. Kutshintsho ngalunye kwiphepha ngalinye, irekhodi ye-WAL ebonakalayo yenziwa kwimemori yephepha. Iirekhodi eziphathekayo, kwakhona, zikwahlulahlulwe zibe yi-2 subtypes: irekhodi ye-snapshot yephepha kunye nerekhodi ye-delta. Ngalo lonke ixesha sitshintsha into ethile kwiphepha kwaye siyidlulisela kwindawo ecocekileyo ukuya kwindawo engcolileyo, ikopi epheleleyo yeli phepha igcinwe kwi-WAL (irekhodi le-snapshot yephepha). Nokuba sitshintshe i-byte enye kuphela kwi-WAL, ingxelo iya kuba nkulu kancinane kunobukhulu bephepha. Ukuba sitshintsha into kwiphepha esele lingcolile, ngoko irekhodi ye-delta yenziwa kwi-WAL, ebonisa utshintsho kuphela xa kuthelekiswa nesimo sangaphambili sephepha, kodwa kungekhona lonke iphepha. Ekubeni ukusetha kwakhona imeko yamaphepha ukusuka kumdaka ukuya kucoceko lwenziwa ngexesha lenkqubo yokukhangela, ngokukhawuleza emva kokuqala kwendawo yokukhangela, phantse zonke iirekhodi eziphathekayo ziya kubandakanya kuphela iziqwenga zamaphepha (ekubeni onke amaphepha ngokukhawuleza emva kokuqala kwendawo yokukhangela icocekile) , emva koko njengoko sisondela kwindawo yokukhangela elandelayo, icandelo lerekhodi le-delta liqala ukukhula kwaye liphinde libuyisele kwakhona ekuqaleni kwendawo yokukhangela elandelayo. Imilinganiselo kwezinye iimvavanyo zokwenziwa zibonise ukuba isabelo samaphepha e-snapshots kwinani elipheleleyo leerekhodi eziphathekayo zifikelela kwi-90%.

Umbono we-WAL yoxinzelelo lwe-snapshot yephepha kukucinezela izifinyezo zephepha usebenzisa isixhobo sokucinezela esenziwe eselenziwe (jonga ucinezelo lwephepha lediski). Kwangaxeshanye, kwi-WAL, iirekhodi zigcinwa ngokulandelelanayo kwimowudi ye-append-kuphela kwaye akukho mfuneko yokubophelela iirekhodi kwimida yeebhloko zesixokelelwano sefayile, ngoko ke apha, ngokungafaniyo nendlela yocinezelo lwephepha lediski, asifuni fayile ezimbalwa apha. yonke; ngokufanelekileyo, lo matshini awuzukusebenza kuphela kwi-OS Linux. Ukongeza, ayisenamsebenzi kuthi ukuba sakwazi kangakanani ukucinezela iphepha. Nokuba sikhulule i-byte eyi-1, esi sele sisiphumo esihle kwaye sinokugcina idatha ecinezelweyo kwi-WAL, ngokungafaniyo noxinzelelo lwephepha lediski, apho sigcina iphepha elicinezelweyo kuphela ukuba sikhulule ngaphezulu kwe-1 ibhloko yenkqubo yefayile.

Amaphepha anedatha ecinezelekileyo kakhulu, isabelo sawo kwivolumu ye-WAL iphezulu kakhulu, ngoko ke ngaphandle kokutshintsha ifayile yefayile ye-WAL sinokufumana ukunciphisa okukhulu kubukhulu bayo. Ukunyanzeliswa, kubandakanywa neerekhodi ezinengqiqo, kuya kufuna utshintsho kwifomathi kunye nokulahlekelwa kokuhambelana, umzekelo, kubathengi bangaphandle abanokuba nomdla kwiirekhodi ezinengqiqo, kodwa abayi kukhokelela ekunciphiseni okukhulu kwefayile.

Njengoxinzelelo lwephepha lediski, ucinezelo lwe-snapshot yephepha le-WAL linokusebenzisa i-ZSTD, LZ4, i-Snappy compression algorithms, kunye ne-SKIP_GARBAGE mode.

Impembelelo yoMsebenzi

Akunzima ukuqaphela ukuba ukwenza ngokuthe ngqo ukunyanzeliswa kwe-WAL ye-snapshot yephepha kuchaphazela kuphela imisonto ebhala idatha kwimemori yephepha, oko kukuthi, loo misonto etshintsha idatha kwi-cache. Ukufunda iirekhodi zomzimba ezivela kwi-WAL kwenzeka kanye kuphela, okwangoku i-node iphakanyisiwe emva kokuwa (kwaye kuphela xa iwela ngexesha lokujonga).

Oku kuchaphazela imisonto etshintsha idatha ngale ndlela ilandelayo: sifumana isiphumo esibi (CPU) ngenxa yesidingo sokucinezela iphepha ngexesha ngalinye phambi kokubhala kwidiski, kunye nesiphumo esihle (idiski IO) ngenxa yokuncipha komthamo idatha ebhaliweyo. Ngako oko, yonke into ilula apha: ukuba ukusebenza kwenkqubo kunqunyelwe yi-CPU, sifumana ukuthotywa okuncinci, ukuba kunqunyelwe yi-disk I / O, sifumana ukwanda.

Ngokungathanga ngqo, ukunciphisa ubungakanani be-WAL kwakhona kuchaphazela (kakuhle) imijelo elahla amacandelo e-WAL kwindawo yokugcina kunye ne-WAL yokudibanisa imisinga.

Iimvavanyo zentsebenzo zangempela kwindawo yethu usebenzisa idatha yokwenziwa ibonise ukunyuka okuncinci (imveliso yanda nge-10% -15%, i-latency yehla nge-10% -15%).

Uvula njani kwaye uqwalasele

Ubuncinci inguqulelo ye-Apache Ignite: 2.8. Yenza kwaye uqwalasele ngolu hlobo lulandelayo:

• Kufuneka kubekho imodyuli ye-iignite-compression kumendo weklasi. Ngokungagqibekanga, ibekwe kunikezelo lwe-Apache Ignite kwi-libs/ulawulo olukhethwayo kwaye ayiqukwanga kwindlela yeklasi. Ungasusa ngokulula ulawulo phezulu kwinqanaba elinye ukuya kwi-libs kwaye xa uqhuba ngapha kwe-ignite.sh iyakwenziwa ukuba yenziwe ngokuzenzekelayo.
• Uzingiso kufuneka luvulwe (Ivulwe nge DataRegionConfiguration.setPersistenceEnabled(true)).
• Imo yocinezelo kufuneka isetwe ngokusebenzisa indlela DataStorageConfiguration.setWalPageCompression(), ucinezelo luvaliwe ngokungagqibekanga (DISABLED mode).
• Ngokuzithandela, unokuseta inqanaba loxinzelelo usebenzisa indlela DataStorageConfiguration.setWalPageCompression(), bona ijavadoc yendlela yamaxabiso asebenzayo kwindlela nganye.

isiphelo

Iindlela zokucinezelwa kwedatha eziqwalaselwayo kwi-Apache Ignite zinokusetyenziswa ngokuzimeleyo enye kwenye, kodwa nayiphi na indibaniselwano yazo iyamkeleka. Ukuqonda indlela asebenza ngayo kuya kukuvumela ukuba uqonde ukuba iyifanele kangakanani na imisebenzi yakho kwindawo okuyo kunye noko kuya kufuneka uyincame xa uyisebenzisa. Uxinzelelo lwephepha leDiski lenzelwe ukucinezela ugcino oluphambili kwaye linokunika umlinganiselo woxinzelelo ophakathi. Uxinzelelo lwe-snapshot yephepha le-WAL liya kunika iqondo eliphakathi loxinzelelo lweefayile ze-WAL, kwaye kunokwenzeka ukuba ziphucule ukusebenza. Ukuhlanganiswa kwe-WAL akuyi kuba nefuthe elihle ekusebenzeni, kodwa kuya kunciphisa ubungakanani beefayile ze-WAL kangangoko kunokwenzeka ngokususa iirekhodi eziphathekayo.

umthombo: www.habr.com