It's been a long time since I studied relational design, but I had a vague memory that it encourages not splitting a table unnecessarily. For instance, given the functional dependencies
K -> A
K -> B
K -> C
my assumption was that the "best" schema is just {KABC} and not something like {KAB, KC} or even {KA, KB, KC}. At least in practice that is how I've seen database designers implement the table.
However, a quick refresher on Wikipedia indicates that the normalization formalism
- doesn't make any statement in the direction of obtaining a "minimal schema",
- 6NF would even require
{KA, KB, KC}. Since 6NF implies the other normal forms, it implies that it is even impossible for them to make such a minimal requirement.
I'm a bit confused that I got this wrong all the time. Does the notion of "obtaining a minimal number of tables" really play no role in formal relational design, and it is just common practice?
Best Answer
The “Normal Forms” are narrowly defined in terms of eliminating redundant data and “update anomalies”. Whether fixing other schema design problems counts as “Normalization” can be debated, but in general parlance Normalization just means ensuring the database complies with some Normal Form.