Session – 8 DATA HANDLING – DISTRIBUTION AND TRANSFORMATION Matakuliah : M0184 / Pengolahan Data Distribusi Tahun : 2005 Versi : Session – 8 DATA HANDLING – DISTRIBUTION AND TRANSFORMATION

OBJECTIVES Integration of heterogeneous database systems Relational database Processing relational queries against the network database

Semantic Approach to the Problem Optimizing the placement and allocation data without considering the requirements of any quantitative cost model directly The goal : to split a global database up into fragments to maximize the efficiency of query execution

Aggregation Relationship between entities is represented as a higher level object. For Example : An “Appointment” entity could be used to represent a relationship between a Patient, a Doctor and a Clinic.

Generalization A set of similar entities is consider to be a single generic entity For Example : A “Person” object could be generalization as a Doctor, a Patient and Nurse entities

Restrictions To obtain a subset of interest give another abstracting mechanism For example : The set “Patient” in the Orthopedic department could form an object called “orthopedic patients”

Semantic Approach to the Problem Cont’d Each local data model is defined by the corresponding DDL and DML semantic To integrate pre-existing heterogeneous database special method of mapping between different data model are needed We should ideally be able to access all of local data via the global model

Getting a relational schema equivalent to network schema To use relational model, we usually need to provide relational views of the local. Four source of data in a network schema which have to be used when getting relational : The record and data item description The associations between owners and members of set types The “duplicates not allowed” location mode for record types The “duplicates not allowed” declaration for set types

Processing Relational Query CUSTOMER CID CName Address Main-Purchase Tot-Purchase PURCHASE Date Price Qty CUST - PUR SALESMAN SID Sname Office Salary SALE - PUR

Processing Relational Query CUSTOMER : CID, Cname, Address, Main-Purchase, Tot-Purchase Key : CID SALESMAN : SID, SName, Office, Salary Key : SID PURCHASE : CID, SID, Date, Price, Qty Key : CID,SID Foreign Key : CID, SID

Processing Relational Query SELECT SName, Office FROM CUSTOMER, SALESMAN, PURCHASE WHERE (Address = “Jakarta”) AND (Main-Purchase = “Lemari”) AND (PURCHASE .CID = CUSTOMER.CID) AND (PURCHASE .SID = SALESMAN.SID)