ofBCNF

ofBCNF is a proposed normalization concept in database theory, designed as a variant of Boyce–Codd Normal Form (BCNF). It was introduced to address practical scenarios where strict BCNF decompositions produce a large number of relations or fail to preserve dependencies significant for application workloads, such as overlapping attribute groups or frequently co-accessed attributes.

Definition and approach: In the ofBCNF framework, a relation schema R with a set F of functional dependencies is considered to be in ofBCNF if it can be decomposed into a collection of subrelations that satisfy lossless-join and a relaxed dependency-preservation criterion. Unlike BCNF, where every nontrivial FD X->Y must have X as a superkey in R, ofBCNF allows certain non-superkey dependencies to be preserved within subrelations when they participate in what is called an overlap-respecting decomposition. The goal is to reduce the number of needless joins while still avoiding update anomalies for the common access patterns.

Relation to other normal forms: ofBCNF sits conceptually between BCNF and 3NF, aiming to provide practical trade-offs. It tends to preserve more dependencies than BCNF without forcing the full dependency-preservation guarantee of 3NF, at the cost of more complex decomposition rules and analysis.

Algorithm and usage: Researchers define procedures to compute an ofBCNF decomposition, often using extended dependency graphs and systematic checks of the relaxed criteria. The concept is primarily of theoretical interest, with occasional application in database design tools that emphasize workload-driven normalization. Its adoption in practice remains limited in standard textbooks.

See also: Boyce–Codd Normal Form; Third Normal Form; database normalization; functional dependency.