Alibaba, daya daga cikin manyan kamfanonin IT na kasar Sin, ya bude lambar tushe na DBMS PolarDB da aka rarraba, bisa PostgreSQL. PolarDB yana ƙaddamar da damar PostgreSQL tare da kayan aiki don rarraba bayanai tare da mutunci da goyan baya ga ma'amaloli na ACID a cikin mahallin duk bayanan duniya da aka rarraba a fadin nodes daban-daban. PolarDB kuma yana goyan bayan aiwatar da binciken SQL da aka rarraba, haƙurin kuskure, da ƙarin ajiyar bayanai don dawo da bayanai bayan ɗaya ko fiye nodes sun kasa. Idan kuna buƙatar faɗaɗa ma'ajiyar ku, zaku iya ƙara sabbin nodes a cikin gungu kawai. An buɗe lambar a ƙarƙashin lasisin Apache 2.0.
PolarDB ya ƙunshi abubuwa biyu - kari da saitin faci don PostgreSQL. Faci yana faɗaɗa ƙarfin tushen PostgreSQL, kuma haɓakawa sun haɗa da abubuwan da aka aiwatar daban da PostgreSQL, kamar tsarin sarrafa ma'amala da aka rarraba, sabis na duniya, na'ura mai sarrafa tambayar SQL da aka rarraba, ƙarin metadata, kayan aikin sarrafa tari, ƙaddamar da tari, da sauƙaƙewa. ƙaurawar tsarin da ake da su zuwa gare shi.
Abubuwan facin suna ƙara wa ainihin PostgreSQL sigar da aka rarraba ta hanyar sarrafa daidaitaccen damar samun bayanai ta amfani da multiversion (MVCC, Multiversion concurrency control) don matakan keɓe daban-daban. Yawancin ayyukan PolarDB an haɗa su a cikin haɓakawa, wanda ke rage dogaro ga PostgreSQL kuma yana sauƙaƙe sabuntawa da aiwatar da mafita dangane da PolarDB (yana sauƙaƙa sauyawa zuwa sabbin juzu'in PostgreSQL da kiyaye cikakken dacewa tare da PostgreSQL). Don sarrafa gungu, ana amfani da kayan aikin pgxc_ctl, dangane da irin wannan kayan aiki daga PostgreSQL-XC da PostgreSQL-XL.
Akwai abubuwa na asali guda uku a cikin tari: nodes na bayanai (DN), cluster manager (CM) da sabis na sarrafa ma'amala (TM). Bugu da ƙari, ana iya amfani da ma'aunin nauyi na wakili. Kowane bangare tsari ne na daban kuma ana iya gudanar da shi akan sabar daban. Ƙididdigar bayanan bayanai suna yin amfani da tambayoyin SQL daga abokan ciniki kuma a lokaci guda suna aiki a matsayin masu gudanarwa na aiwatar da aiwatar da binciken da aka rarraba tare da sa hannu na sauran nodes na bayanai. Manajan tari yana lura da yanayin kowane kullin bayanai, yana adana tsarin tari, kuma yana ba da kayan aiki don sarrafawa, tallafi, daidaita kaya, sabuntawa, farawa, da dakatar da nodes. Sabis ɗin sarrafa ma'amala yana da alhakin kiyaye mutunci gabaɗaya a cikin duka tari.
PolarDB ya dogara ne akan tsarin gine-ginen ƙididdiga na Shared-nothing, bisa ga abin da aka rarraba bayanai lokacin da aka adana a kan nodes daban-daban, ba tare da yin amfani da ajiya na kowa ga duk nodes ba, kuma kowane kumburi yana da alhakin ɓangaren bayanan da ke tattare da shi kuma yana yin tambayoyin da suka danganci. ku data. Kowane tebur yana karkasa zuwa sassa (sharding) ta amfani da hashing dangane da maɓallin farko. Idan buƙatar ta ƙunshi bayanan da ke kan nodes daban-daban, ana kunna tsarin aiwatar da ma'amala da aka rarraba da mai gudanar da ma'amala don tabbatar da atomity, daidaito, keɓewa, da aminci (ACID).
Don tabbatar da haƙurin kuskure, kowane yanki ana maimaita shi zuwa aƙalla nodes uku. Don adana albarkatu, cikakkun bayanai sun haɗa da kwafi biyu kawai, kuma ɗayan yana iyakance ga adana bayanan rubuta-baya (WAL). Ɗaya daga cikin nodes biyu tare da cikakkun kwafi ana zaɓe shi a matsayin jagora kuma yana shiga cikin buƙatun sarrafawa. Kumburi na biyu yana aiki azaman tanadi ga sashin bayanan da ake tambaya, kuma na uku yana shiga cikin zaɓin kullin jagora kuma ana iya amfani dashi don dawo da bayanai idan gazawar nodes biyu tare da cikakkun kwafi. An tsara kwafin bayanai tsakanin nodes ɗin tari ta amfani da Paxos algorithm, wanda ke tabbatar da daidaiton ma'anar yarjejeniya a cikin hanyar sadarwa tare da nodes masu yuwuwar rashin dogaro.
An lura cewa ana shirin bayyana cikakken aikin PolarDB DBMS sama da saki uku: A cikin sigar farko, za a buga kayan aikin kwafi, babban samuwa da sarrafa tari. Saki na biyu zai ƙunshi tsarin aiwatar da ma'amala da aka rarraba wanda ke goyan bayan giciye-kumburi ACID da rarraba aiwatar da SQL. Sakin na uku zai haɗa da plugin don PostgreSQL da kayan aiki don sassauƙan rarraba bayanai a cikin nodes, gami da daidaitawa na sassan sassan don cimma kyakkyawan aiki da ikon faɗaɗa gungu ta ƙara sabbin nodes.
source: budenet.ru