Eyona engundoqo Imisebenzi DBMS

Modern iinkqubo sedata esetyenziswa kwi izinto ezininzi, kodwa wonke umntu uyazi ukuba yintoni na nendlela ungasebenzisa imisebenzi ledatha. Ezi zixhobo inani kakhulu amathuba, ngoko ufanele uqonde ukuba angenza ntoni kwaye yintoni luncedo ukuba umsebenzisi ukusebenzisa ngokupheleleyo kubo.

ulawulo lwedatha

Kwindawo yokuqala, imisebenzi database iquka processing of ulwazi kwimemori bangaphandle, yaye lo msebenzi wenziwa kubonelelo izakhiwo ezisisiseko EP, apho zifuneka nje kuphela sigcine zibandakanyiwe ngqo kwiziko ledatha kodwa ukwenza imisebenzi ofisi ezahlukeneyo, ezifana ukufumana ngokukhawuleza ukufikelela naziphi iifayile ngezihlandlo ezahlukeneyo. Xa embodiments ezithile, ngokubonakalayo basebenzisa ithuba iinkqubo yefayile eyahlukeneyo, ngoxa abanye ukulungiselela umsebenzi, nokuba kwinqanaba izixhobo memory bangaphandle. Kodwa ke kule meko ke kubalulekile ukuqaphela ukuba imisebenzi database, ngezinga eliphezulu yophuhliso, umsebenzisi, xa kunjalo, akukho unolwazi nokuba kusetyenziswa nayiphi na inkqubo, kwaye ukuba kunjalo, njani na ukucwangcisa iifayile. Ingakumbi, le nkqubo sele ekuxhaseni umyalelo yayo azibize izinto zifakiwe kwiziko ledatha.

ulawulo lwezimali RAM

Xa uninzi amatyala umsebenzi ledatha kuqhelekile ukuba usebenzise oovimba kakuhle voluminous kwaye ubukhulu nobuncinane kudla kakhulu kuninzi RAM. Kakade ke, ukuba kwimeko unyango ngenxa yento data nganye iya nokutshintshanisa kunye nememori bangaphandle, isantya yokugqibela kuzakutelekisa isantya nkqubo, ngoko phantse kuphela ukhetho yokwenene kukwandisa data yayo kumthamo in RAM. Kulo mzekelo, kwanokuba indlela yokusebenza inika njengesikhuseli nkqubo ngokubanzi, umzekelo ukuya Unix, a oku akuyi kuba ngokwaneleyo ukuqinisekisa ukuba iziko ledatha le njongo yaye ephambili imisebenzi, njengoko sele umthamo omkhulu lwe data kwi iimpawu abangabaxhamli kumthamo inxalenye nganye ezithile kuvimba kusetyenziswa. Ngenxa kule nkqubo yophuhliso ukuxhasa iseti eyeyalo ezingqubano, kwakunye njengendlela yokuziqeqesha unique indawo yabo.

Kubalulekile ukuphawula inyaniso yokuba kukho umgca olwahlukileyo zokulawula, swi nga ubukho rhoqo kwimemori ye lonke ledatha. Le ndlela isekelwe kwingcinga ukuba kwixa elizayo isixa-RAM kwi computer yakho iya kuba nako ukwandisa khon 'ukuze singabi nawuphi na worry kumthamo, kunye nemisebenzi engundoqo yolu hlobo database apha uya kuwa kanye ngexesha. Okwangoku, yonke le misebenzi kusekho kwisigaba uvavanyo.

ulawulo transaction

A Okwenziwayo ukulandelelana imisebenzi kunye nokusetyenziswa kwenkqubo yolawulo base data lokunyanga njenge lungu elilodwa. Ukuba intengiselwano wabulawa ngokupheleleyo ngempumelelo, inkqubo 'liphuhlisa utshintsho esele ezenziwe nguye, kwimemori bangaphandle okanye akukho nanye kwezi nguqulelo aziyi kuboniswa kwi imeko ledatha. Lo msebenzi iyafuneka ukuze kuxhaswe ingqibelelo ubhalo wesiseko esetyenzisiweyo. Kufuneka kuqatshelwe ukuba ulondolozo kwekhosi oluchanekileyo inkqubo wentengiselwano yinto yokuqala efunekayo xa usebenzisa uvimba olunye-umsebenzisi, injongo kunye nomsebenzi ezahlukileyo kakhulu kwezinye iintlobo lweenkqubo.

Le propati ukuba nawuphi na umcimbi iqala kuphela kwisikolo sikarhulumente engqinelanayo ledatha yaye ngaloo ndlela alishiye kwi imeko enye emva kokuphela inkqubo, iyenza lula kakhulu ukuba ukusebenzisa nakwicandelo yomsebenzi kwiziko ledatha. Kunye nolawulo olululo intengiselwano yenziwe yi KDE ulawulo umsebenzisi ngamnye ngamnye ngaxeshanye, kuloo mgaqo, banokuziva yinxalenye yonke. Nangona kunjalo, oku ngendlela enye ukumelwa enezigaba, njengoko kwiimeko ezininzi xa abantu abasebenza kunjalo baya kukubona ubukho oogxa bakhe ukuba basebenzisa inkqubo multiuser, kodwa enyanisweni inika kanye ingqiqo ledatha. Imisebenzi ezifana ledatha multi-umsebenzisi iye ezinxulumene ne iikhonsepthi yolawulo transaction ezifana isicwangciso uphumezo serial, kunye serialization.

Athetha ntoni?

Serializing transaction parallel ephunyeziweyo kubandakanya ukwakhiwa ekhethekileyo isicwangciso somsebenzi, apho isiphumo iyonke kufikelelwe kulingana ngexabiso umphumo efunyenweyo umxube, ngenxa lokubulawa kwabo yokulandelelana.

Isicwangciso uphumezo Uthotho na isakhiwo ethile inyathelo, nto leyo ekhokelela serialization. Kakade ke, ukuba isixokelelwano ifunyenwe kukubonelela ngokwenene A uphumezo serial zentengiselwano ngumxube, ngoko naliphi na umsebenzisi uvelise intengiselwano, ubukho abanye baya kuba imperceptible ngokupheleleyo, ngaphandle kokuba oko kuya kusebenza kancane kuthelekiswa imo elinye-umsebenzisi.

Kukho ezinye ezisisiseko algorithm serialization. Kwiinkqubo ezingundoqo, ithandwa kakhulu namhlanje ezi ubuchule zisekelwe ungqamaniso capture izinto database ezahlukeneyo. Kwimeko yaso nasiphi na algorithm serialization ubonelela ngamathuba ungquzulwano phakathi iintengiselwano ezimbini okanye ngaphezulu ukufikelela izinto ezithile ledatha. Kwimeko enjalo, ukuxhasa le nkqubo, kufuneka buyisela emva, oko kukuthi, ukuphelisa naziphi na iinguqulelo ezenziweyo kuvimba ngokweenkqubo omnye okanye ngaphezulu. Oku nje enye iimeko apho inkqubo multi-umsebenzisi, omnye uba phambi kwabanye.

ukugawulwa

Enye yeemfuno eziphambili kwiinkqubo mihla ukuqinisekisa ukuthembeka yokugcina ulwazi imemori yangaphandle. Ngokukodwa, zinikeza ukuba omnye imisebenzi ephambili kuvimba iquka ubuchule bokulungisa imeko yokugqibela obanzi ledatha emva kokuvela naziphi na izixhobo okanye hardware ukusilela. Xa uninzi amatyala athatyathiweyo ingqalelo iinketho ezimbini ukusilela zekhompyutha:

• soft, nabanako ukuchazwa njengesikhululo ngesiquphe khomputha yakho (ityala ixhaphakileyo - Power Emergency Off);
• engqongqo, obubonakala ngokuba yincwadi evuliweyo ukulahleka kwenxalenye okanye epheleleyo data egcinwe kwi kwimidiya yangaphandle.

Njengoko software Imizekelo likaxakeka inkqubo cima ikhompyutha xa uzama ukusebenzisa naziphi ukuba omnye imisebenzi ziphambili DBMS ayiqukwanga okanye ngozi nayiphi na into eluncedo yomsebenzisi, apho intengiselwano ethile kungekagqitywa. Le meko lokuqala ingqalelo uhlobo olulodwa ukusilela soft, ngeli xa kwimeko yokugqibela kuyimfuneko ukuze kupheliswe iziphumo zenkqubo enye.

Kakade ke, xa nayiphi na kwimeko yokuphinda ledatha oluqhelekileyo kuyimfuneko ukuba isixa esithile ulwazi olongezelelweyo. Ngamanye amazwi, ukuba ulondolozo eqhelekileyo ukuthembeka yokugcina i data kwisiseko sedata kufuneka uqinisekise i komsebenzi yokugcina ulwazi, yaye inxalenye data lisetyenziswa kwakhona kufuneka kulindwa ngenyameko. Indlela oqhelekileyo ukuqinisekisa ukugcinwa kweenkcukacha ezingasafunekiyo, uthathwa ukuba ukungena utshintsho.

Yintoni na kwaye usebenzise njani?

Le magazini yinxalenye eyodwa ledatha, nto leyo zingafumaneka kwinani imisebenzi database azifakwanga, kwaye igcinwa ngenyameko kakhulu. Kwezinye iimeko, nkqu ngexesha elifanayo inikeza ngexhaso iikopi ezimbini zale magazini, xa zosasazo ezahlukeneyo emzimbeni. Evenkileni wafumana ulwazi malunga naziphi na iinguqu ezenzeka kwindawo engundoqo ye-database, kunye neenkqubo zolawulo ezahlukeneyo utshintsho journaled kumanqanaba ahlukeneyo. Kwezinye iimeko, ungeniso log evumelana ngokupheleleyo othile umsebenzi logic utshintsho, kwindawo ethile - umsebenzi ubuncinane zangaphakathi ezinxulumene zangaphandle ukuguqulwa memory page, lo gama ezinye DBMSs ziquka ukusetyenziswa kudityaniswe iindlela ezimbini.

Xa kunjalo, a-ebizwa ngokuba 'qhinga yokurekhoda pre-kwinjongp "kule magazini. Xa irekhodi yayo isicelo, ibonisa utshintsho kuyo nayiphi na into database luwele imemori yangaphandle phephancwadi phambi kwento bume. Yinto eyaziwayo ukuba imisebenzi Access database iquka ukuthotyelwa eqhelekileyo nale protocol, esebenzisa iphephancwadi ukusombulula naziphi na iingxaki ezinxulumene recovery database xa kuthe kwakho naziphi na ndoyisiwe.

bahlehla

Imeko elula na ukubuyiselwa intengiselwano ngamnye liqengqwa umva. Ngenxa yale nkqubo, akukho mfuneko ukusebenzisa inkqubo ngokubanzi utshintsho yelog, kwaye oko kwanele ukuyisebenzisa for transaction ngalinye imisebenzi imagazini ukuguqulwa zasekuhlaleni, yaye emva koko buyisela emva intengiselwano ngokuzisa imisebenzi Ngokufanayo, ukususela ekupheleni irekhodi nganye. Indlela esakhiwe ngayo umsebenzi ledatha kudla kubandakanya ukusetyenziswa nje isakhiwo ezinjalo, kodwa kwiimeko ezininzi iinkuni asekuhlaleni nangoku aluxhaswanga, yaye ukubuyisela nokuba ngamnye intengiselwano ngamnye wenziwe nkqubo ngokubanzi, ngokuba zonke iirekhodi lwesivumelwano nganye odityanisiweyo uluhlu umva.

Xa kuthe soft ukusilela yangaphandle database memory kungaquka izinto ezahlukeneyo aguqulwe kancincane yi iintengiselwano ayikagqitywa yi lixesha nasisihlo ukungaphumeleli, kwaye inokuba akukho izinto ezahlukeneyo, abo ziphuculwe ukuba ziye zagqitywa ngempumelelo phambi kokuba ityala ngokusebenzisa imixholo RAM lwezimali leyo ubalekela ngokupheleleyo xa kukho iingxaki ezifanayo. Ukuba protocol ziyathotyelwa, ebonelela ukusetyenziswa jenali bobulali ngokuyimfuneko ubhale kwimemori bangaphandle, ezinxulumene ulungiso yazo naziphi na izinto ezinjalo.

Eyona njongo iphambili yale isenzo emva kokuvela kusilela ezithambileyo yimeko inkumbulo olungaphandle database engundoqo eya kuvela kwimeko ukulungisa kwi EAP naluphi na utshintsho for transaction igqityiwe kwaye ngeke ziqulathe imizila iinkqubo ezingaphelelanga. Ukuphumeza oku isiphumo, imisebenzi sedata ephambili kulo mzekelo, buyisela imicimbi uncommitted, phinda lo msebenzi, iziphumo apho ekugqibeleni kuya kuvela kwimemori bangaphandle. Le nkqubo ibandakanya kakhulu oluninzi ubuqili, leyo kakhulu zinxulumene lombutho ulawulo phephancwadi kunye nezithinteli.

ukuhluleka hard

Ukuba kuyimfuneko, buyisela kuvimba emva kukuvela lokungaphumeleli kanzima kuyinto lowu nje kuphela, kodwa kananjalo backup ledatha. Le yokugqibela ikopi epheleleyo database ngelo xesha njengoko phephancwadi yaqala ukugcwalisa. Kakade ke, kufuneka ube nenkqubo recovery eqhelekileyo ufuna ukhuseleko lowu, ke ngoko, njengoko kuchaziwe ngaphambili, ukuba ukugcinakala kwayo kwimemori lwangaphandle ebekwe iimfuno engqongqo kakhulu. Kulo mzekelo, ukufunyanwa database kukuba, olusekelwe phezu iikopi mpepha lowu kudlalwa zonke iintengiselwano olwenziwe lwagqitywa ngexesha lentlekele. Ukuba kuyimfuneko, oko nokuba idlalwe umsebenzi imicimbi ezingaphelelanga yaye aqhubeka nomsebenzi wawo yesiqhelo emva kokuphela inkqubo yokubuyisa ixesha ekuphulukenwe nalo, kodwa ezininzi iinkqubo yokwenene, nkqubo akwenziwanga ngenxa yokuba ngokwayo ukuchacha emva ukusilela nzima yinkqubo elide.

Support ulwimi

Ukusebenza kunye iinkcukacha zale mihla ukusebenzisa iilwimi ezahlukeneyo, yaye ledatha ekuqaleni, ukuqeshwa, imisebenzi kunye nezinye iimpawu ezahlukileyo kakhulu kwinkqubo mihla nokubonelela ngenkxaso ekhethekileyo iilwimi ezininzi. Ezi kakhulu SDL kunye DML, ekujongwe ukuba ukuchaza ledatha onokuyi kunye data ukuxhaphaza, ngokulandelelana.

SDL isetyenziselwa ukuchaza isakhiwo ubhalo-database, oko kukuthi, ukuqonda isakhiwo ethile kwiziko ledatha, efumaneka kubasebenzisi. DML nayo ibandakanya isethi abaqhubi nokuqhathwa lolwazi, ikuvumela ukugcina ulwazi kwidathabheyisi, kwakunye ucime, uguqule kancinane, okanye sebenzisa data ekhoyo.

iimpawu DBMS zibandakanya iintlobo ezahlukeneyo inkxaso ulwimi emanyanisiweyo obonelela zonke izibonelelo ezifunekayo ukuze ukusebenza okuqhelekileyo iinkcukacha, ukususela ekudalweni kwayo ekuqaleni, kwaye inikeza ujongano lomsebenzisi eqhelekileyo. Ulwimi umlinganiselo inika imisebenzi esisiseko ye-database ye ixhaphakileyo imihla yethu iinkqubo zonxulumelwano, esetyenziswa yi SQL.

Yintoni na?

Kwindawo yokuqala ulwimi sidibanisa imisebenzi esisiseko DML kunye SDL, oko kukuthi, inika ithuba izigqibo semantics ezithile kweenkcukacha ezinobume , nokusebenzisa ulwazi oluyimfuneko. izinto database nokuthiywa Ngaloo ezahlukeneyo inkxaso ngqo kwi kwinqanaba lolwimi ngengqiqo ukuba ukuguqulwa ikhutshwa phandle amagama into compiler kwi identifier zazo zangaphakathi, ezisekelwe phezu iitafile inkonzo inkxaso ngokukhethekileyo kubalawuli-. Undoqo kwenkqubo yolawulo, isimiso, angavumelaniyo ngee tafile okanye imiqolo ngamnye.

Ulwimi SQL iquka uluhlu lwezixhobo ezizodwa ukuchaza izithintelo ledatha. Kwakhona, naziphi na izithintelo ezinjalo ziqukiwe kule tafile ezizodwa, iikhathalogu, kunye nokuhlolwa ingqibelelo wenziwa ngqo kwinqanaba loluntu, oko kukuthi kwinkqubo yokufunda ngamnye iingxelo database loguqulelo emafini, ngokusekelwe ziyafumaneka kwi izithintelo ngengqibelelo database, echitha ukujikelezisa ikhowudi ahambelanayo.