Horizonta| Partition relatⅰ on pro」 PROJ PNO PNAME BUDGET LOC P1 Instrumentation Montreal P2 Database Develop. 135000 New York P3CAD/CAM 250000 New York P4 Maintenance 310000Paris PROJ PNO PNAME BUDGET LOC Instrumentation 150000 Montreal P2 Database Develop. 135000 New York PROJ PNAME BUDGET CAD/CAM 255000 New York P4 Maintenance 310000 Paris 2021/2/1 WAMDM Cloud Group
Horizontal Partition relation PROJ 2021/2/11 WAMDM Cloud Group 16
Horizontal fragmentation Primary horizontal fragmentation -to partition a relation by using predicates on that relation Derived horizontal fragmentation -to partition a relation by using predicates on another relation Two aspects affecting fragmentation data information and application information 2021/2/1 WAMDM Cloud Group
Horizontal fragmentation • Primary horizontal fragmentation – to partition a relation by using predicates on that relation • Derived horizontal fragmentation – to partition a relation by using predicates on another relation • Two aspects affecting fragmentation – data information, and – application information 2021/2/11 WAMDM Cloud Group 17
Data information The relationships are important for distribution design Links are used to represent equal joins between relations RI: Relation 1 Owner of I R2: Relation 2 Member of L Link L represents RIpR2 Quantitative information on DB-cardinality of relation R: card (r) 2021/2/1 WAMDM Cloud Group
Data information 2021/2/11 WAMDM Cloud Group 18
Application information Both qualitative and quantitative are needed Definition simple predicate example:LOC=“ New york Minterm predicate Given a set of simple predicates for relation Ri, Pri=(Pin, Pi2,, Pim, the set of minterm predicates Mi=(mi, mi _ mi] is defined as M={m1mb=AP},1≤k≤m,lsj≤ where 2021/2/1 WAMDM Cloud Group
Application information • Both qualitative and quantitative are needed • Definition – simple predicate example: LOC= “New York” – Mintermpredicate 2021/2/11 WAMDM Cloud Group 19
Application information Minterm selectivity -sel(mi) The number of tuples of a relation returned by a query specified by the minterm m Access frequency-acc(mi) The frequency with which user applications access data using a query specified by the minterm m 2021/2/1 WAMDM Cloud Group 20
Application information 2021/2/11 WAMDM Cloud Group 20 Access frequency – acc(mi ) The frequency with which user applications access data using a query specified by the minterm mi Minterm selectivity – sel(mi ) The number of tuples of a relation returned by a query specified by the minterm mi