The chikuru mabasa ari DBMS

Modern Database hurongwa kushandiswa pazvinhu zvizhinji, asi kwete vose vanoziva zvavari uye ungashandisa sei Database mabasa. Ezvemutauro Ava akawandisa zvingangoitika, saka unofanira kunzwisisa kuti vanogona kuita uye chii rinobatsira inodzidzisa kuzvishandisa zvakazara.

date utariri

Pakutanga, ari Database mashandiro zvinosanganisira kubudiswa mashoko ari zvokunze mundangariro, uye kushanda iri urongwa dzinokosha hurongwa ari EP, izvo zvinodiwa kwete chete kuti chitoro mashoko zvakananga zvaisanganisira ari Database asi kuchiita siyana hofisi akadai sokuti kuwana kutsanya kuwana chero mafaira pazviitiko zvakasiyana. Mumamwe embodiments, nokushingaira akashandisa mukana siyana faira mugadziriro, apo vamwe kuriritira basa, kunyange pachiyero kwokunze ndangariro mano. Asi iyi zvinokosha kuziva kuti Database mashandiro, aine anokudzwa okukura, inodzidzisa, chero zvazvingava, haana kuudzwa here chero hurongwa rinoshandiswa, uye kana zvakadaro, sei kuronga mafaira. Kunyanya, hurongwa yave achitsigira ayo padzoro anodana zvinhu zvaisanganisira ari Database.

RAM buffer utariri

Mugore Ruzhinji rwakapindura zviitiko Database basa kwakakurumbira kushandisa nokururamisira voluminous Databases uye shoma kukura kazhinji zvikuru iripo RAM. Chokwadi, kana ari vairapwa nerimwe date chinhu zvichabviswa vakatsinhanisa nezvinhu kwokunze ndangariro, nokumhanya yokupedzisira kuukurira kumhanya wegadziriro, saka anongoda bedzi nzira chaiyo iri kuwedzera ayo buffering Data mu RAM. Muchiitiko chino, kunyange kana uchishandisa hurongwa inopa hurongwa-kwazvo buffer, somuenzaniso Unix, mumwe ichi haangakwaniri rekuona kuti Database iri chinangwa uye chikuru mashandiro, sezvo ane yakakura Vhoriyamu mashoko pamusoro kunobatsira ehupfumi kuti buffering nomumwe zvakananga chikamu Database kushandiswa. Nokuda ichi budiriro hurongwa kutsigira pachake yakatarwa racho buffers, uyewo rakasiyana kuranga kwavo kutsiviwa.

Zvinokosha kucherechedza kuti pane yoga mutsetse rokudzora mugadziriro, nezvezvaiitwawo chichiitwa kuvapo muna kuyeuka rose Database. mirayiridzo iyi inobva kubvuma kuti munguva pfupi uwandu RAM pakombiyuta yako achakwanisa kuwedzera zvokuti harichazonzi upi buffering kunetseka, uye dzinokosha mashandiro kwaiita Database pano achawira chete panguva. Panguva iyoyo, mabasa ose aya vari kuedzwa Pasika achiri.

mutengapwe utariri

A kutengeserana ndiko kutevedzana remapazi nokushandiswa Data chawo utariri hurongwa iyo anobata sezvo rimwe sangano. Kana kutengeserana zvizere vaurayiwa zvinobudirira, kuti hurongwa rinoburitsa kuchinja kwakaitwa naro, muna kwokunze kuyeuka kana hapana kuchinja izvi haingazopedzwizve vakafungisisa mamiriro ari Database. oparesheni ichi chinodiwa kuti kutsigira musoro kuvimbika Database kushandiswa. Zvinofanira kucherechedzwa kuti kwerunyararo yakarurama weboka kutengeserana mashandiro ari chinodiwa kunyange paaishandisa chete-aishandisa Database, chinangwa uye kushanda izvo yakasiyana nemamwe marudzi hurongwa.

Chepfuma chero kutengeserana anotanga chete panguva yakarongeka pehurumende Database uye nokudaro anosiya payo chete mamiriro panopera nzira, zvichiita chaizvo nyore kushandisa sezvo chairema nebasa riri Database. Zvakakodzera kurapa kwema vari akaurayiwa zvakafanana kubudikidza kudzora mamiriro mumwe nomumwe User, pfungwa, vanogona kunzwa chikamu yose. Zvisinei, izvi neimwe nzira imwe idealized amiririrwe, sezvo zvinhu zvakawanda kana kushanda vanhu vachiri achaona kuvapo kwake nevamwe kana vakashandisa multiuser gadziriro, asi chaizvoizvo rinopa chaizvo pfungwa yacho Database. Mabasa akadai multi-User Database yavewo chokuita kutengeserana utariri pfungwa dzakadai Serial kuurayiwa plan, uye serialization.

Ko zvinorevei?

Serializing zvinofambirana executable kutengeserana kunosanganisira rinokosha kuvaka basa ravo plan, sezvamakaropafadzwa zvachose mugumisiro kubudirira kwakafanana mugumisiro akawana nezvakavhenganiswa, nokuda kwavo sequential kuurayiwa.

Serial kuurayiwa hurongwa chinhu chaicho maumbirwo chiito, iyo inosvitsa serialization. Chokwadi, kana hurongwa inotengwa kupa munhu zvechokwadi A Serial kuurayiwa kwema nezvakavhenganiswa, zvino chero anoishandisa uyo wakadenha ari kutengeserana, kuvapo vamwe vachava zvachose imperceptible, asi zvichaita kushanda zvishoma nomumugwagwa kwaitora nguva zvichienzaniswa chete-mushandisi muoti.

Pane zvimwe zvinokosha serialization algorithm. In centralized hurongwa, zvikuru nevakawanda nhasi ndivo algorithms kuti dzinobva yaunonyanya kushandisa kubatwa zvakasiyana Database zvinhu. Kana chipi serialization algorithm anopa mukana kunetsana pakati maviri kana kupfuura kwema pane kuwana dzimwe Database zvinhu. Mumamiriro ezvinhu akadaro, kutsigira nzira iyi, unofanira kufamba shure, kureva kubvisa chero kuchinja akaita Database kuburikidza mumwe kana kupfuura pezvakaitwa. Uyu unongova mumwe ezvinhu apo munhu multi-aishandisa hurongwa, mumwe anonzwa kuvapo nevamwe.

kutema

Mumwe mukuru zvinodiwa kuti ano gadziriro ndiko nechokwadi rakavimbika mashoko okuchengetera ari kwokunze ndangariro. Zvikurukuru, rinopa kuti mumwe mukuru mashandiro ari Database zvinosanganisira kukwanisa kupora wokupedzisira coherent mamiriro Database pashure panowanikwa chero Software kana Hardware kukundikana. In ruzhinji nyaya akatorwa funga zviviri zvokusarudza kuti Hardware kukundikana:

• nyoro, iyo inogona kududzirwa sezvo pakarepo vanorega kombiyuta yako (vakawanda nyaya - Emergency Power Off);
• vanachandagwinyira, izvo kubudikidza kukwana kana kwakakwana kurasikirwa mashoko kuchengetwerwa kwokunze nhau inozivikanwa.

Sezvo Software kukundikana Mienzaniso nechimbichimbi hurongwa shutdown kana kuedza kushandisa chero mukana kuti mumwe mukuru mashandiro ane DBMS haina zvaisanganisira kana anorovera chero aishandisa utility, kwamakadarika haisati yapera imwe mutengapwe. Zvinhu zvokutanga kunganzi somunhu chaiye dzakapfavirira kukundikana mhando, apo pakuparwa yokupedzisira Zvakakodzera kubvisa migumisiro rimwe mutengapwe.

Chokwadi, chero nyaya nokuti kuipa Database kupora zvinokosha kuti mumwe uwandu mamwe mashoko. Nemamwe mashoko, nokuti zvinoitika kwerunyararo rakavimbika umbowo okuchengetera ari Database unofanira nechokwadi redundancy mashoko kuchengetwa, uye chikamu date rinoshandiswa kupora anofanira kurindwa nokungwarira. Nzira vakawanda kuunza kwerunyararo wandisa data, runoonekwa kuti kutema kuchinja.

Chii uye sei kushandisa?

Magazini chinokosha chikamu Database, iri kuvhurwa munyika dzinoverengeka Database mashandiro haaverengwe, uye anodzokororwa vanyatsohuongorora. Mune mamwe mamiriro ezvinhu, kunyange panguva iyoyo rinopa rutsigiro makopi maviri magazini, panguva dzakasiyana chaiko vezvenhau. In kuchitoro vakagamuchira mashoko pamusoro kuchinja chero kuti kuitika huru chikamu Database, uye yakasiyana kuzvidzora nehurongwa kuchinja anogona journaled pamwero yakasiyana-siyana. Mune mamwe mamiriro ezvinhu, danda kupinda kunoenderana zvizere imwe pfungwa mashandiro kuchinja, kumwe - risingamboshandisi womukati oparesheni chokuita kwokunze ndangariro peji nadzurudzo, apo dzimwe DBMSs dzinosanganisira kushandiswa mubatanidzwa mharidzo mbiri.

Chero zvazvingava, Yaunoti "nzira kuti pre-emptive kurekodha" iri mumagazini. In yayo chikumbiro chinyorwa, kunoratidza kuchinja chero Database chinhu muwisira kwokunze ndangariro magazini pamberi shanduka chinhu. Zvinozivikanwa kuti kana mabasa Access Database zvinosanganisira chakaipa zvaidiwa dzakati ichi, kushandisa magazini kugadzirisa chero matambudziko chokuita Database apore ari chiitiko chipi kukundikana.

hazviiti

The nyore mamiriro ndiko kudzorerwa wacho kutengeserana ratokunguruswa. Nokuti nzira ichi, hazvina zvakakodzera kushandisa hurongwa wide kuchinja nerogi, uye zviri zvakakwana kushandisa munharaunda magazini nadzurudzo kuvhiyiwa mumwe kutengeserana, uye ipapo vagokungurusa shure kutengeserana kuburikidza kubata Ivan Kuchin kushandiswa, kubvira kumugumo mumwe chinyorwa. The nemamiriro Database basa kunosanganisira kushandiswa chete maumbirwo kwakadaro, asi kakawanda dzeko matanda achiri haritsigiri, uye kunyange nomumwe rollback nomunhu kwema kuitwa hurongwa-kwazvo, uye nokuda kuti zvose zvinyorwa kutengeserana neumwe zvikabatanidzwa neizvi pasi.

In zvinoitirwawo zvinyoronyoro kukundikana zvokunze Database ndangariro ingasanganisira zvinhu zvakasiyana-siyana kuti chakagadziridzwa kubudikidza kwema haana kunyorwa panguva panowanikwa kukundikana, uye muvepowo hapana zvinhu zvakasiyana, upgraded ndivo vakanga zvapedza pamberi mhosva nokushandisa RAM buffer mukati iyo zvachose haarambi kana paine matambudziko zvakafanana. Kana dzakati iri kutevedzera, kupa kushandisa magazini vemo vari hazvo nyora mune zvokunze ndangariro, izvo chokuita okunatsiridza chero zvinhu zvakadaro.

Chinangwa chikuru yavaipora kwacho pashure panowanikwa nyoro kukundikana ari mamiriro enyika kwokunze ndangariro huru Database, izvo zvaizoita simuka panyaya kugadzira ari EaP chero kuchinja rakapera kutengeserana uye nokudaro haizaiva kungoda kukwana dzokuvhiya. Kuti uite izvi chaizvoizvo guru Database mashandiro ari iyi, rollback uncommitted kwema, kudzokorora oparesheni, migumisiro iyo pakupedzisira handidi kuonekwa mune kwokunze ndangariro. Izvi zvinosanganisira zvikuru zvakawanda subtleties, izvo kazhinji chokuita sangano management nemagazini uye buffers.

Hard kukundikana

Kana zvakakodzera, umutse Database pashure panowanikwa yezvikanganiso zvakaoma haisi chete magazini, asiwo Database negadziriro yeparutivi. Ekupedzisira kopi yakazara Database panguva iyoyo sezvo magazini vakatanga kuzadza. Chokwadi, nokuti zvisingatomboiti kupora nzira kunoda magazini kuchengeteka, naizvozvo, sezvambotaurwa, kuti kuchengetedzwa kwaro kwokunze ndangariro zvavakatemerwa kuzviomesera chaizvo zvinodiwa. Muchiitiko chino, kuzoita kuti Database ndechokuti, kwakavakirwa zvakachengetedzwa makopi magazini vari wakapata zvose kuitiswa kwema kuvakwa panguva njodzi. Kana zvakakodzera, unogona kuridzwa basa kukwana kwema uye mberi kwavo kwagara basa pashure kuguma kupora kwacho, asi mune dzakawanda chaizvo gadziriro, muitiro wakadaro hauna kuitwa nokuti pacharwo kupora pashure kukundikana nesimba pazera refu muitiro.

mutauro Support

Kushanda pamwe Databases ano vanoshandisa mitauro yakasiyana, uye mukutanga Database, kugadzwa, mashandiro uye zvimwe zvinhu zviri yakasiyana chaizvo ano ezvinhu kupa rutsigiro kushandiswa mumitauro akawanda. Ndivo kunyanya SDL uye DML, akaronga rinotsanangura Database schema uye mashoko evanhu, ukuwo.

SDL rinoshandiswa havatsananguri chezvaizoitika nemamiriro Database, ndiko, kuti vazive chaizvo nemamiriro Database, chiri kuwanikwa vanoshandisa. DML zvinosanganisira chine dzaishandisa kuchinja mashoko, kunoita kuti kuchengeta mashoko ari Database, uyewo zvinomuomera kuikanganwa, kuchinja kana kushandisa huripo mashoko.

DBMS zvinhu zvinosanganisira mhando dzakasiyana rutsigiro rimwe mutauro Integrated kuti anogovera vanhu zviwanikwa zvose zvinodiwa kuti chakaipa nokushanda Databases, kubvira kwokutanga chisikwa chacho, uye inopa mureza User inowanikwa. The mutauro mureza kuti anopa rezita Database rakajairika mumazuva edu ndeyeukama hurongwa mashandiro, anoshandiswa SQL.

Chii?

Pakutanga mutauro anosanganisa inokosha DML uye SDL mashandiro, kureva inopa mukana kuziva chaizvo semantics ari ndeyeukama Database , uye konzera kuti anodiwa ruzivo. Saka siyana kutumidza Database zvinhu vachitsigirwa zvakananga pamusoro mutauro pamwero mupfungwa kuti kutendeuka rinoitwa nomudzimu compiler chinhu mazita avo dzakawanda identifiers, inobva vakatsigira basa pamatafura zvikuru-Directories. Chinoumba kudzora mamiriro, pfungwa, asingadi kushamwaridzana matafura kana mumwe pembiru.

The mutauro SQL zvinosanganisira mazita chaiwo zvishandiso kurondedzera Database constraints. Zvakare, chero mitemo yakadaro vanobatanidzwa mune chaidzo matafura, ndaza, uye kuvimbika kuongorora rinoitwa zvakananga pamusoro mitauro yakati sandara, kuti ari mubishi kuverenga nomumwe Database nadzurudzo mashoko compiler, hwakavakirwa kuwanika Database kuperera constraints, anopedzera kuti vaunze zviri runoenzanirana remitemo.