{"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":"

\"TransaksionetDB 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 shum\u00eb-nivele me disa p\u00ebrfitime t\u00eb tjera si transaksionet, funksione t\u00eb shpejta p\u00ebr kalimin p\u00ebrmes pem\u00ebve t\u00eb t\u00eb dh\u00ebnave, bllokimet dhe gjuha e vet ObjectScript.<\/p>\n

M\u00eb shum\u00eb rreth global\u00ebve n\u00eb ciklin e artikujve \u00abGlobalet \u2014 shpata-kahena p\u00ebr ruajtjen e t\u00eb dh\u00ebnave\u00bb:<\/p>\n

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

M\u00eb ka interesuar se si jan\u00eb realizuar transaksionet n\u00eb globalet, \u00e7far\u00eb ve\u00e7orish jan\u00eb aty. Sepse kjo \u00ebsht\u00eb nj\u00eb struktur\u00eb krejt\u00ebsisht tjet\u00ebr p\u00ebr ruajtjen e t\u00eb dh\u00ebnave, ndryshe nga tabelat e njohura. Shum\u00eb m\u00eb e nivelit t\u00eb ul\u00ebt.
\n<\/a><\/noindex>
\nSi\u00e7 dihet nga teoria e bazave t\u00eb t\u00eb dh\u00ebnave relacional, nj\u00eb realizim i mir\u00eb i transaksioneve duhet t\u00eb p\u00ebrmbush\u00eb k\u00ebrkesat ACID<\/a><\/noindex>:<\/p>\n

A \u2014 Atomic (atomik).<\/b> T\u00eb gjitha ndryshimet e b\u00ebra n\u00eb transaksion duhet t\u00eb regjistrohen ose asnj\u00eb prej tyre.<\/p>\n

C \u2014 Consistency (koherenc\u00eb).<\/b> Pas p\u00ebrfundimit t\u00eb transaksionit, gjendja logjike e DB-s\u00eb duhet t\u00eb jet\u00eb e brendshme dhe e q\u00ebndrueshme. N\u00eb mas\u00eb t\u00eb madhe, kjo k\u00ebrkes\u00eb u takon programuesve, por n\u00eb rastin e databazave SQL, ajo gjithashtu ka t\u00eb b\u00ebj\u00eb me \u00e7el\u00ebsat e jasht\u00ebm.<\/p>\n

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

D \u2014 Durable (q\u00ebndrueshm\u00ebri).<\/b> Pas p\u00ebrfundimit t\u00eb suksessh\u00ebm t\u00eb transaksionit, problemet n\u00eb nivelet e poshtme (si\u00e7 \u00ebsht\u00eb nj\u00eb prishje e energjis\u00eb) nuk duhet t\u00eb ndikojn\u00eb n\u00eb t\u00eb dh\u00ebnat e ndryshuara nga transaksioni.<\/p>\n

Globalet jan\u00eb struktura t\u00eb dh\u00ebnash jo relacionale. Ato jan\u00eb krijuar p\u00ebr t\u00eb punuar shum\u00eb shpejt n\u00eb harduer shum\u00eb t\u00eb kufizuar. Le t\u00eb shqyrtojm\u00eb realizimin e transaksioneve n\u00eb globalet me ndihm\u00ebn e imazhit 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 leht\u00eb \u00ebsht\u00eb t\u00eb verifikohet atomik\u00ebsia. Verifikohet nga konsola e databaz\u00ebs.<\/p>\n

Kill ^a\nTSTART\nSet ^a(1) = 1\nSet ^a(2) = 2\nSet ^a(3) = 3\nTCOMMIT<\/code><\/pre>\n
\nPastaj arrijm\u00eb n\u00eb 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 gjith\u00eb gjendja \u00ebsht\u00eb n\u00eb rregull. Atomik\u00ebsia \u00ebsht\u00eb ruajtur: t\u00eb gjitha ndryshimet jan\u00eb regjistruar.<\/p>\n
Le t\u00eb komplikojm\u00eb gj\u00ebn\u00eb, t\u00eb fusim nj\u00eb gabim dhe t\u00eb shohim si do t\u00eb ruaj\u00eb transaksioni, pjes\u00ebrisht ose aspak.<\/p>\n
Tjet\u00ebr her\u00eb do t\u00eb kontrollojm\u00eb 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 aktivizojm\u00eb dhe do t\u00eb shohim. <\/p>\n
docker kill my-iris<\/code><\/pre>\n
\nKjo komand\u00eb \u00ebsht\u00eb praktikisht ekuivalente me ndalimin e detyruesh\u00ebm t\u00eb energjis\u00eb, pasi d\u00ebrgon sinjalin e ndalimit t\u00eb menj\u00ebhersh\u00ebm t\u00eb procesit SIGKILL.<\/p>\n
A mund t\u00eb ket\u00eb ruajtur transaksioni pjes\u00ebrisht?<\/p>\n
SHKRUAJ ^a(1), ^a(2), ^a(3)\n^\n ^a(1)<\/code><\/pre>\n
\n \u2014 Jo, nuk u ruajt.<\/p>\n
T\u00eb provojm\u00eb komand\u00ebn e rikthimit:<\/p>\n
Vrit ^A\nTSTART\nCakto ^a(1) = 1\nCakto ^a(2) = 2\nCakto ^a(3) = 3\nTROLLBACK\n\nSHKRUAJ ^a(1), ^a(2), ^a(3)\n^\n ^a(1)<\/code><\/pre>\n
\nAsgj\u00eb nuk u ruajt gjithashtu.<\/p>\n
2. Koherenca<\/h2>\n
\nDuke pasur parasysh q\u00eb n\u00eb bazat mbi globale, \u00e7el\u00ebsat b\u00ebhen gjithashtu mbi globale (kujdesi q\u00eb globali \u00ebsht\u00eb nj\u00eb struktur\u00eb m\u00eb e ul\u00ebt p\u00ebr ruajtjen e t\u00eb dh\u00ebnave se tabela relacional), p\u00ebr t\u00eb p\u00ebrmbushur k\u00ebrkes\u00ebn e koherenc\u00ebs duhet t\u00eb p\u00ebrfshihet ndryshimi i \u00e7el\u00ebsit n\u00eb t\u00eb nj\u00ebjt\u00ebn transaksion me ndryshimin e globalit.<\/p>\n
P\u00ebr shembull, ne kemi globalin ^person, ku ruajm\u00eb persona 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 kemi krijuar \u00e7el\u00ebsin ^index.<\/p>\n
^index(\u2018Kamenev\u2019, \u2018Sergey\u2019, 1234567) = 1<\/code><\/pre>\n
\nP\u00ebr t\u00eb pasur nj\u00eb baz\u00eb koherente, duhet t\u00eb 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\u00ebr pasoj\u00eb, kur fshijm\u00eb gjithashtu duhet t\u00eb p\u00ebrdorim transaksionin:<\/p>\n
TSTART\nVrit ^person(1234567)\nZKill ^index(\u2018Kamenev\u2019, \u2018Sergey\u2019, 1234567)\nTCOMMIT<\/code><\/pre>\n
\nMe fjal\u00eb t\u00eb tjera, p\u00ebrmbushja e k\u00ebrkes\u00ebs s\u00eb koherenc\u00ebs \u00ebsht\u00eb plot\u00ebsisht mbi supet e programuesit. Por kur flitet p\u00ebr globale \u2014 kjo \u00ebsht\u00eb e natyrshme, p\u00ebr shkak t\u00eb natyr\u00ebs s\u00eb tyre t\u00eb ul\u00ebt.<\/p>\n
3. Izolimi<\/h2>\n
\nK\u00ebtu fillojn\u00eb nd\u00ebrlikimet. Shum\u00eb p\u00ebrdorues punojn\u00eb nj\u00ebkoh\u00ebsisht mbi t\u00eb nj\u00ebjt\u00ebn baz\u00eb, ndryshojn\u00eb t\u00eb dh\u00ebna t\u00eb nj\u00ebjta.<\/p>\n
Situata \u00ebsht\u00eb e krahasueshme me at\u00eb kur shum\u00eb p\u00ebrdorues punojn\u00eb nj\u00ebkoh\u00ebsisht me t\u00eb nj\u00ebjtin repo t\u00eb kodit dhe p\u00ebrpiqen gjithashtu t\u00eb b\u00ebjn\u00eb commit t\u00eb ndryshimeve n\u00eb shum\u00eb skedar\u00eb nj\u00ebkoh\u00ebsisht.<\/p>\n
Baza e t\u00eb dh\u00ebnave duhet ta zgjidh\u00eb k\u00ebt\u00eb n\u00eb koh\u00eb reale. Duke marr\u00eb parasysh q\u00eb n\u00eb kompani serioze ka madje nj\u00eb person t\u00eb ve\u00e7ant\u00eb q\u00eb \u00ebsht\u00eb p\u00ebrgjegj\u00ebs p\u00ebr kontrollin e versioneve (p\u00ebr bashkimin e deg\u00ebve, zgjidhjen e konflikteve, etj.), dhe DB duhet t'i b\u00ebj\u00eb t\u00eb gjitha k\u00ebto n\u00eb koh\u00eb reale, at\u00ebher\u00eb b\u00ebhet e qart\u00eb kompleksiteti i detyr\u00ebs dhe sakt\u00ebsia e projektimit t\u00eb 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 konflikte, n\u00ebse ata punojn\u00eb me t\u00eb nj\u00ebjtat t\u00eb dh\u00ebna. Ajo mund t\u00eb anuloj\u00eb vet\u00ebm nj\u00eb transaksion q\u00eb \u00ebsht\u00eb n\u00eb kund\u00ebrshtim me nj\u00eb tjet\u00ebr ose t'i ekzekutoj\u00eb ato n\u00eb m\u00ebnyr\u00eb sekondare.<\/p>\n
Nj\u00eb tjet\u00ebr problem \u00ebsht\u00eb se gjat\u00eb ekzekutimit t\u00eb nj\u00eb transaksioni (para angazhimit), gjendja e baz\u00ebs mund t\u00eb jet\u00eb e paq\u00ebndrueshme, prandaj \u00ebsht\u00eb e preferueshme q\u00eb transaksionet e tjera t\u00eb mos ken\u00eb akses n\u00eb gjendjen e paq\u00ebndrueshme t\u00eb baz\u00ebs s\u00eb t\u00eb dh\u00ebnave, \u00e7ka realizohet n\u00eb DB rrelacionale p\u00ebrmes shum\u00eb m\u00ebnyrave: krijimin e snapshot-eve, shum\u00ebversionalitetit t\u00eb rreshtave dhe t\u00eb tjer\u00eb.<\/p>\n
Gjat\u00eb ekzekutimit paralel t\u00eb transaksioneve, \u00ebsht\u00eb e r\u00ebnd\u00ebsishme q\u00eb ato t\u00eb mos pengojn\u00eb nj\u00ebra-tjetr\u00ebn. Kjo \u00ebsht\u00eb ajo q\u00eb njihet si pron\u00ebsia e izollimit.<\/p>\n
SQL p\u00ebrcakton 4 nivele izollimi:<\/p>\n