On the normalization in Nested Relational Databases

A comparative study of various nested normal forms

“…For a long time, database designers have been using these normal forms as guides for flat relational database design. In the same spirit, numerous normal forms have recently been defined for nested relations as well [20], [21], [23], [25], [26]. Among all of these cited normal forms, Partition Normal Form (PNF), which is defined in [26], is the most fundamental.…”

“…In essence, PNF basically states that in a nested relation, there can never be distinct tuples that agree on the atomic attributes of either the nested relation itself or of any nested relation embedded within it [26]. Since this is a basic property of nested relations, the nested normal forms defined in [20], [21], [23], [25] all imply PNF.…”

“…Knowing information like this is in fact vital for a successful database design. Hence, the main purpose of this paper is to compare the nested normal forms defined in [20], [21], [23], [25], and to discover their strengths and weaknesses. In particular, we investigate them with respect to generalizing 4NF and BCNF, reducing redundant data values, and design flexibility.…”

“…In addition, we also examine their algorithms and the nested database schemes that they generate. Notice that the comparison among NNF [21], NNF [23], and NNF [25] is already done, as presented in [23], [25], and the results are not reproduced here.…”

“…In the following, for brevity, we abbreviate the nested normal form defined in [20] as NNF [20]. Similarly, the nested normal form defined in [21] is abbreviated as NNF [21], the one defined in [23] as NNF [23], and the one defined in [25] as NNF [25].…”