Data Fragmentation Division of relation r into fragments n,r2,...,r 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. Example relation account with following schema Account =(branch_name,account_number,balance Database System Concepts-5th Edition,Aug 22,2005. 22.8 @Silberschatz,Korth and SudarshanDatabase System Concepts - 5 22.8 ©Silberschatz, Korth and Sudarshan th Edition, Aug 22, 2005. 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. Example : relation account with following schema Account = (branch_name, account_number, balance )