| From the abstract of [1], Codd's stated motivation for applying relation theory to data storage: "Activities of users at terminals and most application programs should remain unaffected when the internal representation of data is changed and even when some aspects of the external representation are changed." From Section 1.4, "Normal Form": "A relation whose domains are all simple can be represented in storage by a two-dimensional column-homogeneous array of the kind discussed above. Some more complicated data structure is necessary for a relation with one or more nonsimple domains. For this reason (and others to be cited below) the possibility of eliminating nonsimple domains appears worth investigating. There is, in fact, a very simple elimination procedure, which we shall call normalization." As I read this, normalization was originally "about" making storage simpler than it was with contemporaneous models. Section 2.3 ("Consistency") discusses how "data bank state" can become inconsistent, and how such inconsistencies might be addressed, up to and including "the user or someone responsible for the security and integrity of the data is notified". I think it's reasonable to infer that guaranteed transactional consistency (what I think kpmah means above by "correctness") and the space-saving properties of eliminating redundant data both happened later, and both fell out of the initial motivation of simplification. [1] https://www.seas.upenn.edu/~zives/03f/cis550/codd.pdf -- E. F. Codd, "A Relational Model of Data for Large Shared Data Banks" |
[The relational model] provides a basis for a high level data language which will yield maximal independence between programs on the one hand and machine representation and organization of data on the other.
A further advantage of the relational view is that it forms a sound basis for treating derivability, redundancy, and consistency of relations [...]
So I would say it is mainly about flexibility, correctness and the possibility to create a simple yet powerful query language.