Data Fragmentation Division of relation r into fragments n,r2,...rn which contain sufficient information to reconstruct relation r. Horizontal fragmentation:each tuple of r is assigned to one or more fragments Vertical fragmentation:the schema for relation r is split into several smaller schemas All schemas must contain a common candidate key(or superkey)to ensure lossless join property. A special attribute,the tuple-id attribute may be added to each schema to serve as a candidate key. Database System Concepts-6th Edition 19.8 @Silberschatz,Korth and SudarshanDatabase System Concepts - 6 19.8 ©Silberschatz, Korth and Sudarshan th Edition Data Fragmentation Division of relation r into fragments r1 , r2 , …, rn which contain sufficient information to reconstruct relation r. Horizontal fragmentation: each tuple of r is assigned to one or more fragments Vertical fragmentation: the schema for relation r is split into several smaller schemas All schemas must contain a common candidate key (or superkey) to ensure lossless join property. A special attribute, the tuple-id attribute may be added to each schema to serve as a candidate key