{"id":36650,"date":"2019-10-31T22:12:54","date_gmt":"2019-10-31T19:12:54","guid":{"rendered":"https:\/\/prohoster.info\/blog\/tranzaktsii-v-globalah-intersystems-iris\/"},"modified":"2019-10-31T22:12:54","modified_gmt":"2019-10-31T19:12:54","slug":"tranzaktsii-v-globalah-intersystems-iris","status":"publish","type":"post","link":"https:\/\/prohoster.info\/sq\/blog\/administrirovanie\/tranzaktsii-v-globalah-intersystems-iris","title":{"rendered":"Transaksionet n\u00eb globalet InterSystems IRIS","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

\"TransaksionetBaza e t\u00eb dh\u00ebnave InterSystems IRIS mb\u00ebshtet struktura interesante p\u00ebr ruajtjen e t\u00eb dh\u00ebnave \u2014 globalet. N\u00eb thelb, k\u00ebto jan\u00eb \u00e7el\u00ebsa me shum\u00eb nivele me disa avantazhe shtes\u00eb si transaksionet, funksionet e shpejta p\u00ebr navigimin e pem\u00ebve t\u00eb t\u00eb dh\u00ebnave, bllokimet dhe gjuh\u00ebn e saj ObjectScript.<\/p>\n

M\u00eb shum\u00eb p\u00ebr globalet n\u00eb ciklin e artikujve \"Globalet \u2014 shpata-magazina p\u00ebr ruajtjen e t\u00eb dh\u00ebnave\":<\/p>\n

Pem\u00ebt. Pjesa 1<\/a><\/noindex>
\nPem\u00ebt. Pjesa 2<\/a><\/noindex>
\nMasa t\u00eb holl\u00eb. Pjesa 3<\/a><\/noindex><\/p>\n

M\u00eb interesonte se si jan\u00eb realizuar transaksionet n\u00eb globalet, \u00e7far\u00eb ve\u00e7orish ka aty. Kjo \u00ebsht\u00eb nj\u00eb struktur\u00eb krejt\u00ebsisht e ndryshme p\u00ebr ruajtjen e t\u00eb dh\u00ebnave se sa tabelat q\u00eb na jan\u00eb b\u00ebr\u00eb t\u00eb zakonshme. Nd\u00ebrsa \u00ebsht\u00eb shum\u00eb m\u00eb e ul\u00ebt n\u00eb nivel.
\n<\/a><\/noindex>
\nSi\u00e7 dihet nga teoria e bazave t\u00eb dh\u00ebnave relacional, nj\u00eb implementim i mir\u00eb i transaksioneve duhet t\u00eb plot\u00ebsoj\u00eb k\u00ebrkesat ACID<\/a><\/noindex>:<\/p>\n

A \u2014 Atomike (atomariteti).<\/b> T\u00eb gjitha ndryshimet e b\u00ebra n\u00eb transaksion regjistrohen ose nuk regjistrohet asnj\u00eb.<\/p>\n

C \u2014 Konsistenc\u00eb (kontradiktor).<\/b> Pas p\u00ebrfundimit t\u00eb transaksionit, gjendja logjike e baz\u00ebs s\u00eb t\u00eb dh\u00ebnave duhet t\u00eb jet\u00eb brenda vet\u00eb-konsistente. N\u00eb nj\u00eb far\u00eb m\u00ebnyre, kjo k\u00ebrkes\u00eb i p\u00ebrket programuesit, por n\u00eb rastin e bazave t\u00eb dh\u00ebnave SQL, ajo i p\u00ebrket gjithashtu \u00e7el\u00ebsave t\u00eb jasht\u00ebm.<\/p>\n

I \u2014 Izolimi (izolueshm\u00ebria).<\/b> Transaksionet q\u00eb ekzekutohen paralelisht nuk duhet t\u00eb ndikojn\u00eb n\u00eb nj\u00ebra-tjetr\u00ebn.<\/p>\n

D \u2014 Q\u00ebndrueshm\u00ebri (q\u00ebndrueshm\u00ebria).<\/b> Pas p\u00ebrfundimit t\u00eb suksessh\u00ebm t\u00eb transaksionit, problemet n\u00eb nivelet e poshtme (si\u00e7 \u00ebsht\u00eb d\u00ebshtimi i furnizimit me energji) nuk duhet t\u00eb ndikojn\u00eb n\u00eb t\u00eb dh\u00ebnat e ndryshuara nga transaksioni.<\/p>\n

Globale jan\u00eb struktura t\u00eb dh\u00ebnash jo-reale. Ato jan\u00eb krijuar p\u00ebr t\u00eb punuar me shpejt\u00ebsi shum\u00eb t\u00eb lart\u00eb n\u00eb hardware shum\u00eb t\u00eb kufizuar. Le t\u00eb shqyrtojm\u00eb implementimin e transaksioneve n\u00eb globale duke p\u00ebrdorur imazhin zyrtar docker t\u00eb IRIS<\/a><\/noindex>.<\/p>\n

P\u00ebr t\u00eb mb\u00ebshtetur transaksionet n\u00eb IRIS p\u00ebrdoren komandat: TSTART<\/a><\/noindex>, TCOMMIT<\/a><\/noindex>, TROLLBACK<\/a><\/noindex>.<\/p>\n

1. Atomik\u00ebsia<\/h2>\n

\nM\u00eb e lehta p\u00ebr t\u00eb verifikuar \u00ebsht\u00eb atomik\u00ebsia. Kontroloni nga konsola e baz\u00ebs s\u00eb t\u00eb dh\u00ebnave.<\/p>\n

Kill ^a\nTSTART\nSet ^a(1) = 1\nSet ^a(2) = 2\nSet ^a(3) = 3\nTCOMMIT<\/code><\/pre>\n
\nM\u00eb pas, nxjerrim p\u00ebrfundimin:<\/p>\n
Write ^a(1), \u201c \u201d, ^a(2), \u201c \u201d, ^a(3)<\/code><\/pre>\n
\nDo t\u00eb marrim:<\/p>\n
1 2 3<\/code><\/pre>\n
\nE gjitha \u00ebsht\u00eb n\u00eb rregull. Atomik\u00ebsia \u00ebsht\u00eb ruajtur: t\u00eb gjitha ndryshimet u regjistruan.<\/p>\n
T\u00eb komplikojm\u00eb pun\u00ebn, t\u00eb introduktojm\u00eb nj\u00eb gabim dhe t\u00eb shohim si do t\u00eb ruhet transaksioni, pjes\u00ebrisht ose aspak.<\/p>\n
Le ta verifikojm\u00eb p\u00ebrs\u00ebri atomik\u00ebsin\u00eb:<\/p>\n
Kill ^A\nTSTART\nSet ^a(1) = 1\nSet ^a(2) = 2\nSet ^a(3) = 3<\/code><\/pre>\n
\nPas k\u00ebsaj, do t\u00eb ndalojm\u00eb me forc\u00eb kontejnerin, do ta rikthejm\u00eb dhe do t\u00eb shohim. <\/p>\n
docker kill my-iris<\/code><\/pre>\n
\nKy kjo komand\u00eb \u00ebsht\u00eb praktikisht ekuivalente me nj\u00eb nd\u00ebrprerje t\u00eb dhunshme t\u00eb energjis\u00eb, pasi d\u00ebrgon sinjalin e menj\u00ebhersh\u00ebm t\u00eb ndalimit t\u00eb procesit SIGKILL.<\/p>\n
A mund t\u00eb jet\u00eb transaksioni ruajtur pjes\u00ebrisht?<\/p>\n
WRITE ^a(1), ^a(2), ^a(3)\n^\n ^a(1)<\/code><\/pre>\n
\n \u2014 Jo, nuk \u00ebsht\u00eb ruajtur.<\/p>\n
Le t\u00eb testojm\u00eb komand\u00ebn e rikthimit:<\/p>\n
Kill ^A\nTSTART\nSet ^a(1) = 1\nSet ^a(2) = 2\nSet ^a(3) = 3\nTROLLBACK\n\nWRITE ^a(1), ^a(2), ^a(3)\n^\n ^a(1)<\/code><\/pre>\n
\nAsgj\u00eb nuk u ruajt.<\/p>\n
2. Konsistenca<\/h2>\n
\nPasi p\u00ebr \u00e7el\u00ebsat n\u00eb global\u00eb, \u00e7el\u00ebsat krijohen gjithashtu n\u00eb global\u00eb (t\u00eb kujtojm\u00eb se globali \u00ebsht\u00eb nj\u00eb struktur\u00eb m\u00eb e ul\u00ebt p\u00ebr ruajtjen e t\u00eb dh\u00ebnave se sa tabela relacional), p\u00ebr t\u00eb p\u00ebrmbushur k\u00ebrkes\u00ebn e konsistenc\u00ebs, \u00ebsht\u00eb e nevojshme q\u00eb ndryshimi i \u00e7el\u00ebsit t\u00eb p\u00ebrfshihet n\u00eb t\u00eb nj\u00ebjt\u00ebn transaksion si ndryshimi i globalit.<\/p>\n
P\u00ebr shembull, ne kemi nj\u00eb global ^person, ku ruajm\u00eb personat dhe si \u00e7el\u00ebs p\u00ebrdorim INN.<\/p>\n
^person(1234567, \u2018firstname\u2019) = \u2018Sergey\u2019\n^person(1234567, \u2018lastname\u2019) = \u2018Kamenev\u2019\n^person(1234567, \u2018phone\u2019) = \u2018+74995555555\n...<\/code><\/pre>\n
\nP\u00ebr t\u00eb pasur nj\u00eb k\u00ebrkim t\u00eb shpejt\u00eb sipas mbiemrit dhe emrit, ne kemi krijuar \u00e7el\u00ebsin ^index.<\/p>\n
^index(\u2018Kamenev\u2019, \u2018Sergey\u2019, 1234567) = 1<\/code><\/pre>\n
\nP\u00ebr t\u00eb ruajtur konsistenc\u00ebn e baz\u00ebs, ne duhet ta shtojm\u00eb personin k\u00ebshtu:<\/p>\n
TSTART\n^person(1234567, \u2018firstname\u2019) = \u2018Sergey\u2019\n^person(1234567, \u2018lastname\u2019) = \u2018Kamenev\u2019\n^person(1234567, \u2018phone\u2019) = \u2018+74995555555\n^index(\u2018Kamenev\u2019, \u2018Sergey\u2019, 1234567) = 1\nTCOMMIT<\/code><\/pre>\n
\nP\u00ebrkat\u00ebsisht, kur fshihen, ne gjithashtu duhet t\u00eb p\u00ebrdorim nj\u00eb transaksion:<\/p>\n
TSTART\nKill ^person(1234567)\nZKill ^index(\u2018Kamenev\u2019, \u2018Sergey\u2019, 1234567)\nTCOMMIT<\/code><\/pre>\n
\nN\u00eb fjal\u00eb t\u00eb tjera, p\u00ebrmbushja e k\u00ebrkes\u00ebs p\u00ebr q\u00ebndrueshm\u00ebri \u00ebsht\u00eb plot\u00ebsisht n\u00eb duar t\u00eb programuesit. Por kur flasim p\u00ebr globale \u2014 kjo \u00ebsht\u00eb e pranueshme, p\u00ebr shkak t\u00eb natyr\u00ebs s\u00eb tyre t\u00eb nivelit t\u00eb ul\u00ebt.<\/p>\n
3. Izolimi<\/h2>\n
\nK\u00ebtu fillojn\u00eb kompleksitetet. Shum\u00eb p\u00ebrdorues punojn\u00eb nj\u00ebkoh\u00ebsisht me t\u00eb nj\u00ebjt\u00ebn baz\u00eb, duke modifikuar t\u00eb nj\u00ebjtat t\u00eb dh\u00ebna.<\/p>\n
Situata \u00ebsht\u00eb krahasueshme me at\u00eb kur shum\u00eb p\u00ebrdorues punojn\u00eb nj\u00ebkoh\u00ebsisht me t\u00eb nj\u00ebjtin depo me kod dhe p\u00ebrpiqen q\u00eb nj\u00ebkoh\u00ebsisht t\u00eb kryejn\u00eb ndryshime n\u00eb shum\u00eb skedar\u00eb.<\/p>\n
Baza e t\u00eb dh\u00ebnave duhet ta menaxhoj\u00eb gjith\u00e7ka n\u00eb koh\u00eb reale. Duke pasur parasysh se n\u00eb kompanit\u00eb e m\u00ebdha ka madje edhe nj\u00eb person t\u00eb ve\u00e7ant\u00eb q\u00eb merret me kontrollin e versioneve (p\u00ebr bashkimet e deg\u00ebve, zgjidhjen e konflikteve, etj.), dhe q\u00eb Baza e t\u00eb Dh\u00ebnave duhet ta b\u00ebj\u00eb gjith\u00e7ka n\u00eb koh\u00eb reale, b\u00ebhet e qart\u00eb sa e nd\u00ebrlikuar \u00ebsht\u00eb kjo detyr\u00eb dhe sakt\u00ebsia n\u00eb projektimin e baz\u00ebs s\u00eb t\u00eb dh\u00ebnave dhe kodit q\u00eb e mb\u00ebshtet at\u00eb.<\/p>\n
Baza e t\u00eb dh\u00ebnave nuk mund t\u00eb kuptoj\u00eb kuptimin e veprimeve q\u00eb kryejn\u00eb p\u00ebrdoruesit p\u00ebr t\u00eb parandaluar konfliktet n\u00ebse ata punojn\u00eb mbi t\u00eb nj\u00ebjtat t\u00eb dh\u00ebna. Ajo mund ta anuloj\u00eb vet\u00ebm nj\u00eb transaksion q\u00eb \u00ebsht\u00eb n\u00eb kontradikt\u00eb me nj\u00eb tjet\u00ebr ose t'i kryej\u00eb ato nj\u00ebri pas tjetrit.<\/p>\n
Nj\u00eb problem tjet\u00ebr \u00ebsht\u00eb se gjat\u00eb ekzekutimit t\u00eb transaksionit (para komitimit), gjendja e baz\u00ebs mund t\u00eb jet\u00eb e paq\u00ebndrueshme, prandaj \u00ebsht\u00eb e preferueshme q\u00eb transaksioneve t\u00eb tjera t'u mohohet akses n\u00eb gjendjen e paq\u00ebndrueshme t\u00eb baz\u00ebs s\u00eb t\u00eb dh\u00ebnave, gj\u00eb q\u00eb arrihet n\u00eb bazat e t\u00eb dh\u00ebnave relationale n\u00eb shum\u00eb m\u00ebnyra: duke krijuar snapshot-e, shum\u00ebversionalizmin e rreshtave, etj.<\/p>\n
Kur ekzekutohen paralelisht transaksionet, \u00ebsht\u00eb e r\u00ebnd\u00ebsishme q\u00eb ato t\u00eb mos nd\u00ebrhyjn\u00eb nj\u00ebra me tjetr\u00ebn. Kjo \u00ebsht\u00eb veti izoluese.<\/p>\n
SQL p\u00ebrcakton 4 nivele izolimi:<\/p>\n