
anusuchi (computer vigyaan)

databases aur lenden prasanskaran (lenden prabandhan) key kshetron mein, ack pranali kii anusuchi (yaa itihas) pranali mein chala rahey lenden key nishpaadan kaa varnan karane key liye ack amoort model haye. aksar yeh samay dwara aadeshit sanchaalan (karyon) kii ack "soochi" hoti haye, joe lenden key ack samooh dwara kii jaati haye joe pranali mein ack saath nishpaadit kii jaati haye. yadi kuchh sanchalanon key beach samay kaa crum pranali dwara nirdhaarit naheen kiya jaataa haye, tou ack "aanshik crum" kaa upayog kiya jaataa haye. iss tarah key sanchaalan key udaaharan hain padhane key liye operation, padhane, likhane, radd karane, karane, taalaa lagaane kaa anurodh karane, taalaa lagaane aadi. sabhi lenden sanchaalan prakaron koo ack anusuchi mein shamil naheen kiya jaanaa chaahiye, aur aamtaur parr kewal chayanit sanchaalan prakaar (ee.jee.kuchh ghatnaaon key baare mein tark karane aur unakaa varnan karane key liye aavashyak detta axes operation) shamil hain. anusuchi aur anusuchi guna databases samvarti niyantran siddhant mein maulik avadhaaranaaen hain.
aupchaarik vivaran.
nimnalikhit ack anusuchi kaa ack udaaharan haih
iss udaaharan mein, kshaitij aksh anusuchi dee mein vibhinn lenden kaa pratinidhitva kartaa haye. urdhvaadhar aksh sanchaalan key samay crum kaa pratinidhitva kartaa haye. anusuchi dee mein teen lenden tii1, tii2, tii3 hotey hain. anusuchi dee. bee. aim. aiss. dwara dekhe gaye lenden key karyon kaa varnan karati haye.
pahale t1 object x koo padhata aur likhata haye, aur phir pratibaddh hotaa haye. phir t2 padhata haye aur y koo apatti karane key liye likhate hain aur pratibaddh hotaa haye, aur anta mein, t3 padhata haye aur z koo apatti karane key liye likhate hain aur pratibaddh hotaa haye. yeh ack "krambaddh" anusuchi kaa ack udaaharan haye, i.ee., samay mein koee overlap key saath anukramik kyonki teenon lenden kii kriyaaen anukramik hain, aur lenden samay mein aapas mein naheen hotey hain.
ack talika dwara oopar dee gaee anusuchi kaa pratinidhitva karna (soochi key bajaay) kewal ack nazar mein pratyek lenden key sanchaalan kii pehchaan karane kii suvidha key liye haye. iss sanketan kaa upayog neeche diye gaye poore lekh mein kiya gayaa haye. iss tarah kii anusuchi kaa pratinidhitva karane key liye takniki saahitya mein ack adhik samanya tarika ack soochi haih
aamtaur parr, databases mein samvarti niyantran key baare mein tark key uddeshya seey, ack operation koo "paramanu" key roop mein model kiya jaataa haye, joe samay mein ack bindu parr, binaa avadhi key hotaa haye. jaba yeh santoshjanak naheen hotaa haye, tou praarambh aur anta samay-bindu aur sambhavatah anya bindu ghatanaaen nirdisht kii jaati hain (shayed hii kabhi). vaastavik nishpaadit sanchaalan kii hamesha kuchh avadhi hoti haye aur unake bheetar ghatnaaon kii ghatana key sambandhit samay nirdisht hotey hain (jaise.jee.," shuruat aur puuraa honey kaa sateek samay), lekin samvarti niyantran tark key liye aamtaur parr poore sanchaalan key samay mein kewal prathamikta (pratyek operation key kaafee jatil vivaranon koo dekhe binaa) mamle, i.ee., joe operation kissy anya operation seey pahale yaa baad mein hotaa haye. isake alawa, kaee mamalon mein, dou vishisht sanchalanon key beach sambandhon seey pahale/baad mein koee fark naheen padata haye aur ise nirdisht naheen kiya jaanaa chaahiye, jabaki sanchaalan key anya jode key liye nirdisht kiya jaa rhaa haye.
samanya taur parr, ack anusuchi mein lenden kaa sanchaalan paraspar hoe sakata haye (i.ee.laine-daine koo samvarti roop seey nishpaadit kiya jaa sakata haye), jabaki pratyek lenden mein sanchaalan key beach samay adesh aparivartit rahate hain jaisa kii lenden key karyakram dwara nihit haye. choonki sabhi lenden key sabhi sanchaalan key beach hamesha samay adesh naheen hotaa haye aur ise nirdisht karane kii aavashyakta hoti haye, isaliye ack anusuchi, samanya roop seey, "kull crum" key bajaay sanchaalan key beach ack "aanshik crum" haye (jahaan pratyek jodee key liye crum nirdhaarit kiya jaataa haye, jaisa kii sanchaalan kii soochi mein haye). samanya mamle mein bhee, pratyek lenden mein kaee prakriyaaen hoe sakati hain, aur swayam koo kull crum key bajaay sanchaalan key aanshik crum dwara thheek seey darshaaya jaa sakata haye. iss prakaar, samanya roop seey, ack anusuchi sanchaalan kaa ack aanshik crum haye, jisamen isake sabhi lenden key aanshik adesh (embedding) hotey hain.
dou sanchalanon key beach samay-crum koo inn sanchalanon key ack "aadeshit jodee" dwara darshaaya jaa sakata haye (jaise.jee.ack jodee (opp1, opp2) key astitva kaa arth haye kii opp1 hamesha opp2 seey pahale hotaa haye), aur samanya mamle mein ack anusuchi aise krambaddh jode kaa ack samooh haye. aisaa samooh, ack anusuchi, ack aanshik crum haye jise ack "chakreeya nirdeshit graph" (yaa "nirdeshit chakreeya graph", dagg) dwara darshaaya jaa sakata haye jisamen nodes key roop mein sanchaalan aur ack nirdeshit kinare key roop mein samay-crum (kissy bhee chakr kii anumati naheen haye kyonki ack chakr kaa matlab haye kii ack chakr parr pahala (koee bhee) sanchaalan chakr parr dusare operation seey pahale aur baad mein (kissy bhee) donon hoe sakata haye, joe samay kii hamari dhaarana kaa khandan kartaa haye). kaee mamalon mein, iss tarah key graph kaa ack chitramaya pratinidhitva ack anusuchi koo pradarshit karane key liye upayog kiya jaataa haye.
tippanih choonki sanchaalan kii soochi (aur iss lekh mein upayog kii gaee talika sanketan) hamesha sanchaalan key beach ack kull crum kaa pratinidhitva karati haye, isaliye joe anusuchi kull crum naheen haye, usey soochi dwara naheen darshaaya jaa sakata haye (lekin hamesha ack dagg dwara darshaaya jaa sakata haye).
anusuchi key prakaar.
dharavahik.
laine-daine gair-antarit kiye jaate hain (oopar udaaharan dekhein)
aaee.ee.ack kramik anusuchi vaha haye jisamen koee lenden taba taka shuru naheen hotaa jaba taka kii ack chala rhaa lenden samaapt naheen hoe jaataa.
krambaddh.
ack anusuchi joe ack crum anusuchi key barabar (isake parinam mein) haye, mein krambaddhata guna hotaa haye.
anusuchi ee mein, jiss crum mein lenden kii kriyaaen nishpaadit kii jaati hain, vaha dee mein samaan naheen haye, lekin anta mein, ee dee key samaan parinam detaa haye.
paraspar virodhi kaary.
dou karyon koo sangharsh (paraspar virodhi jodee) kahaa jaataa haye yadih
nimnalikhit karyon kaa samooh paraspar virodhi haih 
jabaki nimnalikhit kriyaaen naheen hainh 
sangharsh samaantaa.
anusoochiyon aiss1 aur aiss2 koo sangharsh-samatulya kahaa jaataa haye yadi nimnalikhit dou shartein santusht hainh
sangharsh-krambaddh.
ack anusuchi koo sangharsh-krambaddh kahaa jaataa haye jaba anusuchi ack yaa adhik krambaddh anusuchi key liye sangharsh-samatulya hoti haye.
sangharsh-kramikta key liye ack aur paribhasha yeh haye kii ack anusuchi sangharsh-kramik haye yadi aur kewal tabhi jaba iska prathamikta graph/kramikta graph, jaba kewal pratibaddh lenden parr vichaar kiya jaataa haye, tou acyclic haye (yadi graph koo asambaddh lenden koo bhee shamil karane key liye paribhaashit kiya gayaa haye, tou asambaddh lenden seey judey chakr sangharsh kramikta ullanghan key binaa hoe sakate hain).
joe crum anusuchi <t1, t2> key liye sangharsh-samatulya haye, lekin <t2, t1> naheen haye.
pratibaddhata-aadeshit.
ack anusuchi koo pratibaddhata-aadeshit (pratibaddh-aadeshit), yaa pratibaddhata-adesh-krambaddh kahaa jaataa haye, yadi yeh pratibaddhata adesh (saha; bhee pratibaddh-adesh yaa pratibaddh-crum-krambaddhata) anusuchi sampatti kaa paalan kartaa haye. iska matlab haye kii laine-daine kii pratibaddhata ghatnaaon key samay kaa crum sambandhit lenden key prathamikta (aanshik) crum key saath sangat haye, jaisa kii unake anusuchi key acyclic vareeyata graph (kramikta graph, sangharsh graph) dwara prerit haye. iska tatparya haye kii yeh sangharsh-krambaddh bhee haye. saha-sampatti vishesh roop seey vitarit pranaliyon mein vaishvik kramikta praapt karane key liye prabhaavi haye.
tippanih pratibaddhata adesh, jisaki khoj 1990 mein kii gaee thee, spasht roop seey (bernstein aitt all mein ullekh naheen kiya gayaa haye. 1987). isaki sahee paribhasha (veekam aur vosen 2001) mein dikhaai detee haye, haalaanki isaki sambandhit takneekon aur siddhant kaa vivaran aanshik, galat aur bhraamak haye. pratibaddhata adesh aur isake sroton key vyaapak coverage key liye "pratibaddhata adesh" aur "pratibaddhata adesh kaa itihas" dekhein.
samaantaa dekhein.
dou anusoochiyon aiss1 aur aiss2 koo drishya-samatulya kahaa jaataa haye jaba nimnalikhit shartein santusht hoti hainh
drishya-krambaddh.
ack anusuchi koo dekhane-krambaddh kahaa jaataa haye yadi yeh kissy krambaddh anusuchi key drishya-samkaksh haye. 
dhyaan dein kii paribhasha key anusaar, sabhi sangharsh-krambaddh anusoochiyaan drishya-krambaddh hain.
dhyaan dein kii uparokt udaaharan (joe sangharsh-krambaddh charcha mein udaaharan key samaan haye) ack hii samay mein drishya-krambaddh aur sangharsh-krambaddh donon haye. haalaanki, drishya-krambaddh anusoochiyaan hain joe sangharsh-krambaddh naheen hainh way anusoochiyaan joe ack andhe lekhan kaa pradarshan karane vaale lenden key saath hainh
uparokt udaaharan sangharsh-krambaddh naheen haye, lekin yeh drishya-krambaddh haye kyonki isamen ack drishya-samatulya crum anusuchi <t1 haye,. tii2,. t3>.
choonki yeh nirdhaarit karna kii kyaa ack anusuchi drishya-krambaddh haye, aine. pee.-poorna haye, isaliye drishya-krambaddhata mein bahut cumm vyaavhaarik ruchi haye.
punarpraapt karane yogya.
laine-daine kewal una sabhi laine-denon key baad hotey hain jinake parivartan way padhate hain, karate hain.
yeye anusoochiyaan punarpraapt karane yogya hain. f punarpraapt karane yogya haye kyonki t1, t2 seey pahale pratibaddh hotaa haye, jisase t2 dwara padhaa gayaa maan sahee hoe jaataa haye. taba tii2 khud koo pratibaddh curr sakata haye. f2 mein, yadi t1 kaa garbhpaat kiya jaataa haye, tou t2 koo nirast karna padata haye kyonki iska padhaa huaa maan galat haye. donon hii mamalon mein, databases ack susangat sthiti mein chhod diyaa jaataa haye.
apraapya.
yadi koee laine-daine t1 samaapt hoe jaataa haye, aur ack laine-daine t2 pratibaddh hotaa haye, lekin t2 t1 parr nirbhar kartaa haye, tou hamaare paas ack aparivartaniya anusuchi haye.
iss udaaharan mein, g apraapya haye, kyonki t2 t1 dwara likhe gaye key maan koo padhata haye, aur pratibaddh haye. t1 koo baad mein nirast curr diyaa gayaa, isaliye t2 dwara padhaa gayaa maan galat haye, lekin choonki t2 pratibaddh haye, isaliye yeh anusuchi punarpraapt naheen kii jaa sakati haye.
cascadeless.
cascading aborts (aeye. see. aeye.) seey bhee bachana. isase bachaa jaataa haye kii ack ekal lenden radd honey seey lenden kii ack shrinkhala vaapas aaa jaati haye. cascading aborts koo rokane kii ack ranneeti ack lenden koo usee anusuchi mein dusare lenden seey asambaddh parivartanon koo padhane seey manaa karna haye.
nimnalikhit udaaharan vahee hain joe punarpraapt karane yogya parr charcha mein hainh
iss udaaharan mein, halanki f2 punarpraapt karane yogya haye, lekin isase bachaa naheen jaa sakata haye. 
cascading aborts. yeh dekhaa jaa sakata haye kii yadi t1 nirast hoe jaataa haye, tou t2 koo karna hoga 
anusuchi kii shuddhata banaae rakhane key liye garbhpaat bhee kiya jaae 
jaisa kii t2 pahale seey hii t1 dwara likhe gaye asambaddh moolya koo padh chuka haye.
nimnalikhit ack punarpraapt karane yogya anusuchi haye joe cascading garbhpaat seey bachaati haye. haalaanki, dhyaan dein kii a/t1 kaa adyatan hamesha khou jaataa haye (kyonki t1 koo nirast curr diyaa gayaa haye).
dhyaan dein kii yadi tii1 pratibaddh hoga tou yeh anusuchi krambaddh naheen hogi.
cascading aborts seey bachana paryaapt haye lekin ack anusuchi key punarpraapt karane yogya honey key liye aavashyak naheen haye.
sakht.
ack anusuchi sakht haye-isamen sakhti kii sampatti haye-yadi kissy bhee dou lenden key liye t1, t2, yadi t1 kaa lekhan sanchaalan t2 key "paraspar virodhi" sanchaalan seey pahale hotaa haye (yaa tou padhaa yaa likhaa), tou t1 kaa pratibaddh yaa nirast ghatana bhee t2 key usa paraspar virodhi sanchaalan seey pahale hoti haye.
koee bhee sakht anusuchi cascade-less haye, lekin isake vipareet naheen haye. sakhti viphalata seey databases kii kushal vasuli kii anumati detee haye.
kramikta vargon key beach padaanukramit sambandh.
nimnalikhit abhivyaktiyaan kramikta aur punarpraapti vargon key beach padaanukramit (niyantran) sambandhon koo darshaati hainh
wein aarekh (neeche) uparokt khandon koo chitraatmak roop seey darshaata haye.
vyaavhaarik karyanvayan.
vyavhaar mein, adhikansh samanya uddeshya databases system sangharsh-krambaddh aur punarpraapt karane yogya (mukhya roop seey sakht) anusoochiyon koo niyojit karate hain.

