1、山東大學碩士學位論文基于WEB的分布式數(shù)據(jù)庫查詢姓名：周立力申請學位級別：碩士專業(yè)：計算機應(yīng)用技術(shù)指導教師：趙合計20031115山東大學碩士學位論文ABSTRACTTheworkofthispaperaimsatanenterpriseorasubtradesystemwhichdepartmentsdistributeindifferentdistrictssothatitneedstheinformationconnectiona
2、crosstheregionandtimeandwhichinformationprimarilyscattersinthedatabaseswithdifferentstructuresandplacedindifferentsites.SodistributeddatabasequeryingthroughtheInternetisrequiredtoprovidethetransparentefficaciousandrealti
3、meinformationfortheenterprise.Themaintaskofallisthedistributeddatabasequeryinthestudy.WebsdistributedtraitmakeitselfbecomeonegoodplatformofdatabaseapplicationthenBSthreelayers(multilayer)architectureadapteditbeusedforthe
4、platformofdistributedapplicationinthestudyThispaperfocusontheresearchofastrategyofimprovingthesystemresponsespeedreducingthenetworkflowandoptimizingdistributeddatabasequery.Theoptimizationtargetofdistributedqueryistosche
5、meout“thesatisfiedalgorithm“butnotnecessarilytoseek“thebestofallalgorithm“.Thecorepartofdistributedqueryalgorithmisaglobalqueryoptimizationalgorithm.Thequeryrequestisdecomposedtosubqueriestask.Andasfaraspossiblemakesubqu
6、eriestoprocesstogether.Asubqueryneedstobeconsideredtheefficiencyinacertainnodeandtobeperformedinthebestappropriatenode.Somesubqueriesarerequiredtochangetheperformedorderbecauseofnotparallelprocessing.Thequerytypeisdivide
7、dintothreelayers:atomquerysimplequery(includeindeterminationquerymergequeryconjunctionquery)andcombinationquery.Thequeryingiscompletelytransparenttocustomer.Globalqueryrequestreferredbycustomerisdecomposedtonativelocalqu
8、ery(namelysubquery)requestthatseveralrelatednodesallcanidentify.Theneverysubqueryisexecuted.Thatistotranslatecombinationqueryintosimplequerythentranslatesimplequeryintoatomquery.Lastthequeryinginformationcomingfromeachno
9、degatherstogetherforcustomerThedistributeddatabasequeryofthepaperdesignthequerycomputingseparatelyaccordingtothequeryrequestofeachcustomer.Conjunctionqueryanditssemijoinquerytechniqueandcombinationstrategyof一....州..一.一..