云计算及应用课件：SQL or NoSQL

SQLorNoSQL?TheNoSQLMovementMeetupJune112009inSanFranciscoNoSQLnameproposedbyEricEvans2004BigTable(Google)2007Dynamo(Amazon)2008Cassandra(Facebook)Hadoop/HBase(Yahoo)ProjectVoldemort(LinkedIn)NoSQLConferencesRelationalDatabase/SQL19801981BernsteinandGoodmanMulti-versionConcurrencyControlDatabaseTimeline197019701990200020101969CODASYL-Networkdatabase-Schema-DDL/DML1970CoddRelationalModel1980GrayTransaction1995BernsteinetalCritiqueofANSISQLIsolationLevels1989SQL-891992SQL-921999SQL:1999ObjectRelational2003SQL:2003Analyticsextensions1979Oracle1974SEQUELRowColumnRelationalModelNormalizeddata“Atomic”Multi-columnKeyOperationsontables:select,project,joinRelationshiponkeyPrimaryKeyForeignKeyTable–n-tupleKeyDatabaseSummaryCostsFixedschemaNormalizationTransformdataonloadCostofscalingProblemswithlargeobjectsComplicatedsoftwareBenefitsMaturetechnologyPrecisequeryingStarSchema–historicdataTupleStore/NoSQLTupleStorageSystemsGoogleDatabaseSystemChubby–Lock/metadatamanagerGoogleFileSystem–DistributedfilesystemBigtable–TuplestorageonGFSMapReduce–DataprocessingontuplesOthertuplestoresVoldemort–AmazonDynamoCassandraHBaseHypertableTupleStoreModelOneTableOperateonMapSetof(Key,Value)StructuredKeyUnstructuredValueOperations:select,projectMapReduceTupleStoreKeyValueKeyColumnTimestampMapReduceDefinetwofunctionsMapInput:tupleOutput:listoftuplesReduceInput:key,listofvaluesOutput:listortupleSpecifyaclusterSpecifyinputandoutputtuplestoresFrameworkdoestherest{Map(k1,v1)}->{list(k2,v2)}{list(k2,v2)}->{(k2,list(v2))}{Reduce(k2,list(v2))}->{list(v3)

} ->{(k2,v3)}MapReduceExampleForeachwebpagecountthenumberofpagesthatreferencethatpage

InputtuplestoreisWWWMapFunction:foreachanchoronwebpage,emit(anchorURL,1)ReduceFunction:emit(anchorURL,sum(list)){Map(k1,v1)}->{list(k2,v2)}{list(k2,v2)}->{(k2,list(v2))}{Reduce(k2,list(v2))}->{(k2,v3)

}URLWebPageURLWebPageURLWebPageURLWebPage…Outputtuplestoreis

{(URL,count)}ExampleinSQLCREATETABLElinks( URLpageNOTNULL, URLref_pageNOTNULL, PRIMARYKEYpage,ref_page)SELECTref_page,count(DISTINCTpage)FROMlinksGROUPBYref_pageForeachwebpagecountthenumberofpagesthatreferencethatpage

TupleStoreSummarySemi-structureddataNoneedtonormalizedataSimpleimplementationsCheap,fast,scalableMapReduceProcessingSimpleprogramming(forgeeks)IssuesNoguidancefromschemaNomodelforhistoricdataHadoopwinsSortBenchmarkSynthesisSummarySQLStructureddataPreciseHistoricdataNeedstransformationScalabilityissuesNoSQLCheapScalableHandleslargedataSummarySQL优势：保持数据的一致性（事务处理）由于以标准化为前提，数据更新的开销很小（相同的字段基本上都只有一处）可以进行Join等复杂查询其中能够保持数据的一致性是关系型数据库的最大优势。不足：大量数据的写入处理为有数据更新的表做索引或表结构（schema）变更字段不固定时应用对简单查询需要快速返回结果的处理读写集中在一个数据库上让数据库不堪重负，大部分网站已使用主从复制技术实现读写分离数据库分割之后，如果一定要进行Join处理，就必须要在程序中进行关联，这是非常困难的EnterpriseModelMoneyContentAnalytics?NoSQLRelationalDBMe