Re: Sixth normal form
Date: Wed, 12 Jun 2013 07:47:20 -0700 (PDT)
Message-ID: <df9badf6-b40e-4847-92c3-d479c759bc7f_at_googlegroups.com>
Dana srijeda, 5. lipnja 2013. 11:52:49 UTC+2, korisnik jmlet..._at_gmail.com napisao je:
> and there is only one On Monday, July 30, 2007 6:45:00 AM UTC-4, Sameeksha wrote:
I think, it is good to understand that “6NF” has no theoretical significance. The definition of "6NF" does not provide a procedure that will "Relvar" bring into "6NF". The authors of “6NF” understand that 6NF is important, but they do not understand that “6NF” is not matter of functional and join dependences. The decomposition of a structure into binary (atomic) structures is what is important here. Atomic structures imply many important consequences, not only for databases, but also for a range of other sciences. For example, we can directly determine truth value for the atomic sentences. However, if sentence is complex we need additional tool for determining its truth value, that is, we need truth tables. Note that the truth tables are not proved in mathematics. And mathematics is not intuitive science. Here is also the issue of atomic structures in mathematics, semantics, linguistics, cognitive science and philosophy as well as their construction. Note that relations have the corresponding predicates.
At this User Group, I gave the example of the relation whose attributes are mutually independent. In this case we have “all key” relvar. This example shows that “6NF” is an absurd, because there are relations who are in “6NF”, but these relations have keys that are composed of a large number of attributes. Theoretically the number of these attributes can be any finite number of attributes. “Simple Form” which I presented billow in this post can decompose mutually independent attributes. In fact, entities with mutually independent attributes mean good construction of these entities. Any restriction on the mutually independent attributes, including functional dependency, is an additional requirement, which needs especially take into consideration.
In my paper "Some ideas about a new data model" at http://www.dbdesign10.com it was shown the procedure of the decomposition of data structures into the corresponding binary structures. (Presented in2005). In my paper, "Database design and data model founded on concept and knowledge constructs" at this http://www.dbdesign11.com I have introduced some other generalizations regarding the mentioned decomposition, see section 4.2. 9 (Presented in 2008).
In my paper, "Database design and data model founded on concept and knowledge constructs" at this http://www.dbdesign11.com I have introduced some other generalizations regarding the mentioned decomposition, see section 4.2. 9 (Presented in 2008). In my papers from 2008 and 2012, I presented decomposition of a file into the corresponding binary files as well as the decompositions of concepts into the corresponding binary concepts at ER level. (see http://www.dbdesign11.com )
In 2006 I presented “Simple Form”, see section 4 at http://www.dbdesign10.com : Relation schema R (K, A1, A2,…, An) is in Simple Form if R satisfies: R (K, A1, A2, …,An) = R1 (K, A1) join R2 (K, A2), join … join Rn (K, An) if and only if
- Key K is simple
- A1, A2,… , An are mutually independent.
In fact, in the current theory of database design, it is not precisely defined what are the first steps. Simple Form defines a first step in the db design. Simple Form is introduced only for one reason; it determines and constructs the attributes and the simple key for entities. Mutually independent attributes in RM correspond to the intrinsic attributes on ER level. Note that any limitation of the mutually independent attributes I threat as a constraint. In contrast to so-called “6NF”, Simple Form completely determines construction of entities. Note that "6NF" requires that we first need to do the following NFs: 1NF, 2NF, 3NF, BCNF, 4NF, ETNF, RFNF, SKNF and 5NF.
Note that the "Simple Form" enables the introduction of constraints only after determining of attributes and binary structures. So, I separate the design of attributes from the design of constraints. Therefore the simple key is presented in the abstract object i.e. the key is presented in a database. It also demonstrates that the key is one thing i.e. the key is one wholeness.
Lately, there have appeared papers which are completely based on 6NF. For example the following papers:
1.
“Anchor Modeling An agile Modeling Technique using the Sixth Normal Form for Structurally and Temporally Evolving Data”
On this user group I showed that this paper is wrong in many aspects, see my thread "some information about anchor modeling." For example in my post from this thread, from April 1, 2013, I showed 11 major errors in paper Anchor Modeling.
2.
“Translating data between XML schema and 6nf conceptual models”. This paper also has 6NF in the title.
This paper writes in details about Anchor Modeling, I think that the paper is a master thesis.
3.
“Database design & relational theory Normal Forms & all that jazz”.
This book is interesting case, because it was written by C. Date, who is co-author of "6NF". C. Date writes about "Anchors" as a well-known fact in db theory. However, he wonders if anchor recalls on Codd's paper RM / T ? “…Does this state of affairs remind you of the RM/T discipline…” (See page 211). Note that “anchor” is the main construct in Anchor Modeling and is defined as the surrogate key, see reference [19].
4.
“Modern approaches to data warehouse design”, Tine Borovnik, Master thesis, University Ljubljana, Slovenia, 03.09.2010.
Section 4.2 is devoted to Anchor Modeling
As I wrote above, Anchor Modeling has many errors and incorrect solutions. So all of these paperss are based on a theory that is wrong. In addition, these works use "6NF" as fundamentals.
So, as a conclusion of my post, you can accept my claims, which are clearly outlined in my thread "some information about anchor modeling." Note that this my claims, so far, no one has denied. In this case, the above-mentioned four papers may cause some kind of the chaos in the field of the theory of the database. I guess that has a lot more papers, which are based on "6NF", here I listed the ones that I saw.
On the other hand you or someone else can claim on this user group that my claims are false. Of course in this case, the claims must be justified.
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> > Googling out for definition and explanation for sixth normal form only
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> > resulted in the following information - "6th normal form states that a
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> > relation R should not contain any non-trivial join dependencies". Also
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> > everywhere it is stated that this normal form takes into account the
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> > temporal (time) dimension to the relational model, and that current
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> > implementations like SQL server 2005 do not implement this normal
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> > form.
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> >
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> > Any more explanation and preferably an example would help in
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> > understanding the concept behind this normal form.
Vladimir Odrljin Received on Wed Jun 12 2013 - 16:47:20 CEST