简介:许多NoSQL(不仅SQL)数据库在数据的巨大的数量上被建议到店和询问。他们中的一些喜欢BigTable,PNUTS,和HBase,能是散布了订的表格(点)被建模。许多另外的索引技术被介绍了为点在非关键的列上支持询问。然而,没有这些技术的全面分析或比较,它在为某个工作量选择或求婚一种合适的索引技术把麻烦带到用户。这份报纸基于六建议一个分类索引问题分类在点上索引技术并且提供最先进的技术的全面评论。基于分类,我们建议一个表演模型说出QSModel从Tencent估计质问时间和实际工作量上的这些技术和跑实验的存储费用评估这个模型。最大的错误质问时间和存储费用评估的结果表演分别地是24.2%和9.8%。而且,我们建议IndexComparator,实现代表性的索引的一个开放源代码工程技术。因此,用户们能基于理论分析和实际实验选择最好合适的索引技术。
简介:AniterativemethodofDeJong,GreigandMadan(1985)forobtainingmaximumlikelihoodestimatesforcontingencytablesderivedfromaMover-Stayermodelisconsidered.Itisshownthatthismethodworksforothersamplingschemesleadingtoincompletecontingencytables.Moreover,compar-isonsindicatethatthemethodisveryfast.
简介:ItwassbownbyFormanekandSibleythatthegroupdeterminantcharacterizesafinitegroupGuptoisomorphism.HoehnkeandJohnson(independentlytheauthors-usinganargumentofManafield)showedthecorrespondingresultfork-characters,k=1,2,3.Thenotionofk-charactersdatesbacktoFrobenius.TheyaredeterminedbythegroupdeterminantandmaybederivedfromthecharactertableCT(G)providedoneknowsadditionallythefunctionsφk:G×…×G→C(G),(g1,…,gk)→Cg1…gk,whereC(G)={Cg,g∈G}denotesthesetofconjugacyclassesofG.Theobjectofthepaperistopresentcriteriaforfinitesgroups(morepreciselyforsolublegroupsGandHwhicharebothsemi-directproductsofasimilartype)when1.GandHhaveisomorphicspectraltables(i.e.,theyformaBrauerpair),2.GandHhaveisomorphictableofmarks(inparticulartheBurnsideringsareisomorphic),3.GandHhavethesame2-characters.Usingthistheauthorscoustructtwonon-isomorphicsolublegroupsforwhichallthesethreerepresentation-theoreticalinvariantscoincide.
简介:Theproblemofpovertyanditsreliefinthemedievalcitieshasbeenthesubjectofaseriesofstudiessince1970s.Intheabsenceofcentralcontrollingorganizationengagedintheprovisionandsupervisionofassistancetothepoor,medievalcharitableinstitutionsseemtoprovidesomescopeforaclosestudyoftheexperienceofpovertyanditsrelief.Fromthecharitableactivityonecandiscoverafieldofsocialinteractionandsocialrelationsinlatemedievalcities.Inthelastthirtyyearsespecially,socialhistoriansofEuropehavecarriedoutvaluableprimaryresearchinthefieldofpovertyandpoorrelief.Somehaveconcentratedononeurbansociety,andothershavedealtwith