petalmind
Joined 6 years ago
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544
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102
Member since
Nov 28
https://databasedesignbook.com/
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Comment · 3 months ago
> to just copy a bash command from a website and run it (sometimes with sudo! O.o ) to install software.
how is that different from the good old days of
wget ftp://ftp.something.org/software-2.10.tar.gz
tar zxfv
./configure
make
sudo make install
?Comment · 4 months ago
Claude Epitaph
Comment · 6 months ago
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.
Comment · 6 months ago
Thank you, your take on the evolution from spreadsheets to proper databases is englightening.
Comment · 6 months ago
Could you share an example of writing stule that you enjoy?
Comment · 6 months ago
> Might it be a consequence of lack of disk space in those early decades
A plausible explanation of "normalization as a process" was actually found in https://www.cargocultcode.com/normalization-is-not-a-process... ("So where did it begin?").
I hope someday to find some technical report of migrating to the relational database, from around that time.
Comment · 6 months ago
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.
I'm super frustrated. This paper is 14 years old.
Comment · 6 months ago
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.
This is my big teaching pet peeve.
Comment · 6 months ago
Yeah, no NULL is ever equal to any other NULL, so they are basically unique.
Comment · 6 months ago
> 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).
Also, the numeric sequence is not very useful because there are at least four non-numeric forms (https://andreipall.github.io/sql/database-normalization/).
Also, personally I think that 6NF should be foundational, but that's a separate matter.
Comment · 6 months ago
Frankly I don't think that overcounting is solved by normalizing, because it's easy to write an overcounting SQL query over perfectly normalized data.
I tried to explain the real cause of overcounting in my "Modern Guide to SQL JOINs":
https://kb.databasedesignbook.com/posts/sql-joins/#understan...
Comment · 6 months ago
One day I hope to write about denormalization, explained explicitly via JOINs.