A normal form for preventing redundant tuples in relational databases

We introduce a new normal form, called essential tuple normal form (ETNF), for relations in a relational database where the constraints are given by functional dependencies and join dependencies. ETNF lies strictly between fourth normal form and fifth normal form (5NF, also known as projection-join normal form). We show that ETNF, although strictly weaker than 5NF, is exactly as effective as 5NF in eliminating redundancy of tuples. Our definition of ETNF is semantic, in that it is defined in terms of tuple redundancy. We give a syntactic characterization of ETNF, which says that a relation schema is in ETNF if and only if it is in Boyce-Codd normal form and some component of every explicitly declared join dependency of the schema is a superkey. Categories and Subject Descriptors H.2.1 [Database Management]: Logical Design—normal forms, schema and subschema General Terms Algorithms, Design, Theory Keywords database design, redundancy, essential tuple normal form, fourth normal fo...

• Type: Journal
• Year: 2012
• Where: ICDT
• Authors: Hugh Darwen, C. J. Date, Ronald Fagin
• Keywords: Boyce Codd Normal Form, Database, Functional Dependencies, ICDT 2012, Syntactic Characterization