Attributye-Pair Range Rules

摘要

This paer examines the properties of metadata in hte form of IF THEN rules which ocntain two predicates on attributes of a raltional databasdse table.For example: a (15..30)=> d(243 .. 271),which means "if the vblaue of attribute a' in a tuple is in the range 15 to 30 then the value of attirbute 'd'will be in the range 243 to 271." Metadata of htis kind is useful in Semantic Query optimisation and remote Cache Mangemnt.The two predicates (antecedenty and consequent) in each rule are Selection Conditions or conttraints of the type found in database queries.Each condition therefore denotes a subset of a database table.Rules ca be cascaded,using subrange ocntainment as the link between successive rules.the set of rules cna therefore be regrded as a set of edges in a Condition Dependecty Graph,and using hte rule-set is path discovery in the graphj.The prupose of th ecurrent paper is to introduce some of hte propreties of ht ecurrent paper is to introduce some of the properties of tttibute-pair range rules.