Izinkemba zangempela zesizindalwazi - ama-globals - kade zaziwa, kodwa bambalwa abazi ukuthi zisetshenziswa kanjani ngempumelelo noma abanaso nhlobo lesi sikhali esikhulu.
Uma usebenzisa ama-globals ekuxazululeni lezo zinkinga abanekhono ngempela kuzo, ungakwazi ukuthola imiphumela evelele. Kuphakathi kokukhiqiza noma ekwenzeni lula isixazululo senkinga (, ).
Ama-Globals ayindlela ekhethekile yokugcina nokucubungula idatha, ehluke ngokuphelele kumatafula aku-SQL. Bavela ngo-1966 ngolimi (intuthuko yokuziphendukela kwemvelo - , ngemuva kwalokhu COS) kusizindalwazi sezokwelapha futhi isekhona , futhi yaphinde yangena kwezinye izindawo lapho kudingeka ukwethembeka nokusebenza okuphezulu: ezezimali, ukuhweba, njll.
Ama-Global kuma-DBMS esimanje asekela ukuthengiselana, ukugawulwa kwemithi, ukuphindaphinda, nokuhlukanisa. Labo. zingasetshenziselwa ukwakha izinhlelo zesimanje, ezithembekile, ezisabalalisiwe nezisheshayo.
I-Globals ayikukhawuleli kumodeli yobudlelwano. Bakunikeza inkululeko yokuthuthukisa izakhiwo zedatha ezithuthukiselwe imisebenzi ethile. Ezinhlelweni eziningi, ukusetshenziswa okuhlakaniphile kwama-global kungaba yisikhali esiyimfihlo ngempela, okuletha ukusebenza onjiniyela bohlelo lokusebenza abangaphupha ngakho kuphela.
Ama-Globals njengendlela yokugcina idatha angasetshenziswa ezilimini eziningi zokuhlela zesimanje, ezisezingeni eliphezulu nezisezingeni eliphansi. Ngakho-ke, kulesi sihloko ngizogxila kakhulu kuma-globals, hhayi olimini abaphuma kulo.
2. Indlela ama-globals asebenza ngayo
Ake siqale siqonde ukuthi ama-globals asebenza kanjani nokuthi ayini amandla awo. Ama-Globals angabhekwa ngezindlela ezahlukene zokubuka. Kule ngxenye yesihloko sizozibheka njengezihlahla. Noma njengezindawo zokugcina idatha ezilandelanayo.
Ukukubeka kalula, i-global iwuhlelo oluqhubekayo. Amalungu afanayo alondolozwa ngokuzenzakalelayo kudiski.
Kunzima ukucabanga into elula yokugcina idatha. Ngekhodi (ngezilimi ze-COS/M) ihlukile ohlwini olujwayelekile lokuhlanganisa kuphela kuphawu ^ ngaphambi kwegama.
Ukuze ulondoloze idatha emhlabeni jikelele, awudingi ukufunda ulimi lombuzo lwe-SQL; imiyalo yokusebenza nabo ilula kakhulu. Zingafundwa ngehora.
Ake siqale ngesibonelo esilula. Isihlahla esinezinga elilodwa esinamagatsha ama-2. Izibonelo zibhalwe nge-COS.
Set ^a("+7926X") = "John Sidorov"
Set ^a("+7916Y") = "Sergey Smith"
Lapho ufaka ulwazi emhlabeni jikelele (Setha umyalo), izinto ezi-3 ziyenzeka ngokuzenzakalelayo:
- Ilondoloza idatha kudiski.
- Ukwenza inkomba. Okukhona kubakaki kuwukhiye (ezincwadini zesiNgisi - “subscript”), futhi ngakwesokudla kokulinganayo yinani (“inani le-node”).
- Iyahlunga. Idatha ihlungwa ngokhiye. Esikhathini esizayo, lapho udabula uhlu, into yokuqala izoba "uSergey Smith", neyesibili "John Sidorov". Lapho ithola uhlu lwabasebenzisi abavela emhlabeni wonke, isizindalwazi asichithi isikhathi sokuhlunga. Ngaphezu kwalokho, ungacela ukukhishwa kohlu oluhlungiwe, kusukela kunoma yimuphi ukhiye, ngisho nongekho (okukhiphayo kuzoqala kukhiye wokuqala wangempela, oza ngemva kwalowo ongekho).
Yonke le misebenzi yenzeka ngokushesha okukhulu. Kukhompyutha yami yasekhaya bengithola amanani afika ku-750/isekhondi ngenqubo eyodwa. Kuma-multi-core processors amanani angafinyelelwa ifaka/isekhondi.
Yiqiniso, isivinini sokufaka ngokwaso asisho okuningi. Ungakwazi, isibonelo, ukubhala ngokushesha ulwazi kumafayela ombhalo - kanje Ukucubungula i-visa kusebenza. Kodwa endabeni yama-globals, sithola isitoreji esinenkomba esihlelekile njengomphumela, esingasetshenzwa kalula futhi ngokushesha esikhathini esizayo.
- Amandla amakhulu omhlaba yijubane okungafakwa ngalo amanodi amasha.
- Idatha emhlabeni ihlale ifakwe ohlwini. Ukuwadabula, kokubili ezingeni elilodwa nokujula esihlahleni, kuhlala kushesha.
Ake sengeze amanye amagatsha ambalwa ezingeni lesibili nelesithathu emhlabeni jikelele.
Set ^a("+7926X", "city") = "Moscow"
Set ^a("+7926X", "city", "street") = "Req Square"
Set ^a("+7926X", "age") = 25
Set ^a("+7916Y", "city") = "London"
Set ^a("+7916Y", "city", "street") = "Baker Street"
Set ^a("+7916Y", "age") = 36
Kusobala ukuthi izihlahla ezinamazinga amaningi zingakhiwa ngokusekelwe emhlabeni jikelele. Ngaphezu kwalokho, ukufinyelela kunoma iyiphi i-node cishe kuyashesha ngenxa ye-auto-indexing ngesikhathi sokufakwa. Futhi kunoma yiliphi izinga lesihlahla, wonke amagatsha ahlungwa ngokhiye.
Njengoba ubona, ulwazi lungagcinwa kukho kokubili ukhiye kanye nevelu. Ubude bokhiye obuphelele (isamba sobude bazo zonke izinkomba) bungafinyelela , kanye namagugu okwenqolobane. Inani lamazinga esihlahleni (inombolo yobukhulu) ngama-31.
Elinye iphuzu elithakazelisayo. Ungakha isihlahla ngaphandle kokucacisa amanani ama-node wamazinga aphezulu.
Set ^b("a", "b", "c", "d") = 1
Set ^b("a", "b", "c", "e") = 2
Set ^b("a", "b", "f", "g") = 3
Imibuthano engenalutho amanodi angenalo inani elinikeziwe.
Ukuze uqonde kangcono ama-globals, ake siwaqhathanise nezinye izihlahla: izihlahla zengadi nezihlahla zegama lesistimu yefayela.
Ake siqhathanise izihlahla ezisemhlabeni nezakhiwo ezijwayeleke kakhulu zohlelo kithina: nezihlahla ezijwayelekile ezikhula ezingadini nasemasimini, kanye nezinhlelo zamafayela.
Njengoba sibona ezihlahleni zasengadini, amaqabunga nezithelo kutholakala kuphela ekugcineni kwamagatsha.
Amasistimu wefayela - imininingwane igcinwa kuphela ekugcineni kwamagatsha, okungamagama amafayela afaneleke ngokugcwele.
Futhi nasi isakhiwo sedatha yomhlaba wonke.
Umehluko:
- Amanodi angaphakathi: ukwaziswa emhlabeni wonke kungagcinwa kuzo zonke izindawo, hhayi ekugcineni kwamagatsha.
- Amanodi angaphandle: Umhlaba jikelele kumele ube namanani achaziwe ekugcineni kwamagatsha, kuyilapho i-FS nezihlahla zengadi zingakwenzi.
Ngokuphathelene nama-node angaphakathi, singasho ukuthi isakhiwo somhlaba wonke siyi-superset yesakhiwo samagama ezihlahla ezinhlelweni zefayela nezihlahla zengadi. Labo. nezimo kakhudlwana.
Ngokuvamile, umhlaba jikelele isihlahla esi-odwe esinekhono lokugcina idatha endaweni ngayinye.
Ukuze uqonde kangcono umsebenzi womhlaba wonke, ake sicabange ukuthi bekungenzekani uma abadali bezinhlelo zamafayela besebenzisa indlela efana neyembulunga yonke ukuze bagcine ulwazi?
- Ukususa ifayela elilodwa kuhla lwemibhalo kuzosusa ngokuzenzakalelayo uhla lwemibhalo, kanye nazo zonke iziqondiso ezingaphezulu eziqukethe uhla lwemibhalo olulodwa kuphela olusanda kususwa.
- Ngeke kube nesidingo sezinkomba. Bekuzoba khona amafayela anamafayili amancane namafayela angenawo amafayili amancane. Uma kuqhathaniswa nesihlahla esivamile, igatsha ngalinye liyoba isithelo.
- Izinto ezifana namafayela e-README.txt angase angadingeki. Konke okwakudingeka kushiwo mayelana nokuqukethwe kohla lwemibhalo kwakungabhalwa kufayela lohla lwemibhalo ngokwalo. Esikhaleni sendlela, igama lefayela alihlukaniseki egameni lenkomba, ngakho-ke bekungenzeka ukuthi udlule ngamafayela nje.
- Isivinini sokususa izinkomba ezinemibhalo engezansi efakwe esidlekeni singakhuphuka kakhulu. Izikhathi eziningi ku-Habré kube nezindatshana mayelana nokuthi kuyisikhathi esingakanani futhi kunzima kangakanani ukususa izigidi zamafayela amancane (, ). Kodwa-ke, uma wenza isistimu yefayela-mbumbulu emhlabeni jikelele, kuzothatha imizuzwana noma izingxenyana zayo. Lapho ngihlola ukususa izihlahla ezingaphansi kukhompyutha yasekhaya, kususe amanodi ayizigidi ezingama-1-96 esihlahleni esinezigaba ezimbili ku-HDD (hhayi i-SSD) ngomzuzwana ongu-341. Ngaphezu kwalokho, sikhuluma ngokususa ingxenye yesihlahla, hhayi nje lonke ifayela elinama-globals.
Ukususa izihlahla ezingaphansi kungenye iphuzu eliqinile lomhlaba jikelele. Awudingi ukuphindaphinda kulokhu. Lokhu kwenzeka ngokushesha okukhulu.
Esihlahleni sethu lokhu kungenziwa ngomyalo Kill.
Kill ^a("+7926X")
Ukuze siqonde kangcono ukuthi yiziphi izenzo ezitholakala kithi emhlabeni jikelele, ngizohlinzeka ngethebula elifushane.
Imiyalo eyisisekelo nemisebenzi yokusebenza nama-globals e-COS
Ukusetha amagatsha ku-node (uma ingakachazwa) namanani e-node
Ikopisha umucu ongezansi
Ukukhipha isihlahla esincane
Isusa inani lenodi ethile. Umuthi ongaphansi ophuma ku-node awuthintwa
Ukunqamula ngokuphelele kwesihlahla, kungene phakathi esihlahleni
Amagatsha ahambayo we-node ethile
Ihlola ukuthi i-node ichaziwe
Ikhulisa nge-athomu inani le-node. Ukuze ugweme ukwenza ukufunda nokubhala, kwe-ACID. Muva nje kunconyiwe ukuthi ushintshele ku
Siyabonga ngokunaka kwakho, sesilungele ukuphendula imibuzo yakho.
Disclaimer: Lesi sihloko kanye nokuphawula kwami kuso kuwumbono wami futhi akuhlobene nesimo esisemthethweni se-InterSystems Corporation.
Ukuqhubeka . Uzofunda ukuthi yiziphi izinhlobo zedatha ezingaboniswa emhlabeni wonke nokuthi imiphi imisebenzi enikeza inzuzo enkulu.
Source: www.habr.com