CS 257 Database Systems Principles Assignment 1 Instructor: Student: Dr. T. Y. Lin Rajan Vyas (119)

Modes of Information Integration

Information Information Integration allows database or other distributed information to work together. Three most common approaches:  Federated Database  DataWareHousing  Mediators

Federations  The simplest architecture for integrating several DBs  One to one connections between all pairs of DBs  n DBs talk to each other, n(n-1) wrappers are needed  Good when communications between DBs are limited

Federated Database System Sources are independent, but one source can call on others to supply information. One-to-One connection between the all pairs of databases DB 1 DB 4 DB 2 DB 3

Dealer 1 NeededCars(mode1, color, autotrans) Dealer 2 Autos(seria1, model, color) Options(seria1, option) Dealer 1 to Dealer 2 f or ( e a ch t u p l e (:m, : c, :a) in neededCars ) i f ( : a = TRUE) { /* automatic transmission wanted */ SELECT s e r i a l FROM Autos, Options WHERE Autos.seria1 = Options.seria1 AND Options.option = 'autoTrans' AND Autos.mode1 = :m AND Autos.color = :c; } e l s e { /* automatic transmission not wanted */ SELECT serial FROM Autos WHERE Autos.mode1 = :m AND Autos.color = :c AND NOT EXISTS ( SELECT * FROM Options WHERE s e r i a l = Autos.seria1 AND option = 'autoTrans' }; } } Dealer 3 Cars(serialN0, model, color, autoTrans,...)

Data Warehouse  Sources are translated from their local schema to a global schema and copied to a central DB.  User transparent: user uses Data Warehouse just like an ordinary DB  User is not allowed to update Data Warehouse

Information Copies sources of data from several sources are stored in a single database. User Query Result Ware House Combiner Extractor 2 Extractor 1 Sour ce 1 Sour ce 2

Example Construct a data warehouse from sources DB of 2 car dealers: Dealer-1’s schema: Cars(serialNo, model,color,autoTrans,cdPlayer,…) Dealer-2’s schema: Auto(serial,model,color) Options(serial,option) Warehouse’s schema: AutoWhse(serialNo,model,color,autoTrans,dealer) Extractor --- Query to extract data from Dealer-1’s data: INSERT INTO AutosWhse(serialNo, model, color, autoTans, dealer) SELECT serialNo,model,color,autoTrans,’dealer1’ From Cars;

Extractor --- Query to extract data from Dealer-2’s data: INSERT INTO AutosWhse(serialNo, model, color, autoTans, dealer) SELECT serialNo,model,color,’yes’,’dealer2’ FROM Autos,Options WHERE Autos.serial=Options.serial AND option=‘autoTrans’; INSERT INTO AutosWhse(serialNo, model, color, autoTans, dealer) SELECT serialNo,model,color,’no’,’dealer2’ FROM Autos WHERE NOT EXISTS ( SELECT * FROM serial =Autos.serial AND option = ‘autoTrans’);

Mediators

It is a software component that supports a virtual database. It stores no data of its own. User Query Result Mediator Wrapper Sour ce 1 Sour ce 2

Extractor for translating Dealer-2 data to the warehouse INSERT INTO AutosWhse(serialNo, model, color,autoTrans, dealer) SELECT s e r i a l, model, color, ' y e s ', 'dealer2' FROM Autos, Options WHERE Autos.seria1 = Options.seria1 AND option = 'autoTrans'; INSERT INTO AutosWhse(serialNo, model, color,autoTrans, dealer) SELECT s e r i a l, model, color, 'no', 'dealer2‘ FROM Autos WHERE NOT EXISTS ( SELECT * FROM Options WHERE s e r i a l = Autos.seria1 AND option = 'autoTrans' );

Thank You