I think I understand this "Cartesian product" reasoning behind 4NF/5NF, I just find it irrelevant I guess.
Cartesian product is explained in Kent: case (3) in https://www.bkent.net/Doc/simple5.htm#label4.1 ("A "cross-product" form, where for each employee, there must be a record for every possible pairing of one of his skills with one of his languages")
I do not explicitly mention this Cartesian product even tho it is present in both posts ("sports / languages" in 4NF, and "brands / flavours" in 5NF).
> it demonstrates [one of] the precise problem[s] the normal form sets out to solve: a combinatorial explosion of rows.
I just don't understand this wording of "a combinatorial explosion of rows" — what's so dramatic here? I don't need four iterations of algebra-dense papers to explain this concept, I think it's pretty simple frankly.
And my implicit argument is, I guess, exactly that you could design tables that handle both problems without invoking 4NF and 5NF — people are doing that all the time.
I have so many questions about that. Should that normal form basically replace 5NF for the purposes of teaching?
Why do they hate us and do not provide any illustrative real-life example without using algebraic notation? Is it even possible?
I just want to see a CREATE TABLE statement, and some illustrative SELECT statements. The standard examples always give just the dataset, but dataset examples are often ambiguous.
> (in its joins)
Do you understand what are "its" joins? What is even "it" here.
Imperative mood "normalize" assumes that you had something not-normalized before you received that instruction. It's not useful when your table design strategy is already normalization-preserving, such as the most basic textbook strategy (a table per anchor, a column per attribute or 1:N link, a 2-column table per M:N link).
And this is basically the main point of my critique of 4NF and 5NF. They both traditionally present an unexplained table that is supposed to be normalized. But it's not clear where does this original structure come from. Why are its own authors not aware about the (arguably, quite simple) concept of normalization?
It's like saying that to in order to implement an algorithm you have to remove bugs from its original implementation — where does this implementation come from?
The other side of this coin is that lots of real-world design have a lot of denormalized representations that are often reasonably-well engineered.
Because of that if you, as a novice, look at a typical production schema, and you have this "thou shalt normalize" instruction, you'll be confused.
> Someone, somewhere writing down a list and that list being blessed with the imprimatur of Academic Approval (TM)
One problem is that normal forms are underspecified even by the academy.
E.g., Millist W. Vincent "A corrected 5NF definition for relational database design" (1997) (!) shows that the traditional definition of 5NF was deficient. 5NF was introduced in 1979 (I was one year old then).
2NF and 3NF should basically be merged into BCNF, if I understand correctly, and treated like a general case (as per Darwen).
Do you know if Redex could be a tool that would be useful in my situation?
Claude suggests it, but I need to learn a lot of Redex to understand how to apply it.
I have a general understanding of what operational semantics is. Or maybe, are there any Redex implementations for common programming languages? \lambda_v is a bit too abstract.
> on the 'reflection' level, where most languages have specific keywords that cannot be used 'first class' with the rest of the language.
In Ruby this is also the other way around, and it's one of my pet peeves.
`Kernel#callcc` looks like a method (arguably, of a special class), yet it's impossible to re-implement directly in the language, as far as I can tell.
Same with `raise`, I keep forgetting that it's not a keyword even.
Yeah, I was also going to say that conflating trivial syntax and "supremely easy to learn" is a very weak flex.
The first Smalltalk-80 book you randomly find is 560 pages.
Also, there is a weird bargaining with "but not block temporaries" and "not an instance variable". Why not? Half of the postcard is basically empty. Also, "except primitives" — how many primitives are there?
Lisp has completely different runtime semantics. Even the lexical scope in Ruby is extremely peculiar. One of the hard parts of writing this document was to remove the intuitive influence of Lisp because it just doesn't make sense for Ruby.
Question: but how many different numbers can you fit in 64 bits using your encoding (sorry I understand the general approach but I have no idea how that fast hierarchy works). I guess it's still 2^64 different numbers?
So basically you have a very low density of representable numbers (2^64 / w218), I wonder how quickly it grows as you use more and more 1-bits, and is there even a correlation between the bit pattern and the corresponding number value?