Readit NewsWhat's the argument for avoiding distinct? Is it performance? I've often wondered if the (sometimes redundant) distincts slow things down. Perhaps it does, but just not enough that I noticed.
Primary reason: distinct on every select shows either lack of knowledge of schema, in particular which columns make rows unique, or unfortunate schema design. (Apart from niche cases, schema should be somewhat normal. I.e. column parent_name belongs in the table parent, not in the table student)
Select a from x where myuniquekey=1; —- guaranted to return 1 or zero rows, if myuiniquekey is actually unique.
Select a from x join y on x.parent_id = y.y_id —- guaranteed to return same amount of rows as exist in y, never more, never duplicates y rows. (N-to-1 relation)
If distinct is used in any of above, then question “why?” naturally arises.
In more severe case, leads to bugs:
Select distinct student.student_name, parent.parent_name from student join parent on student.parent_id = parent.parent_id —- silently discards rows, where by accident student/parent name combo matches several times.
Technically sql allows comparing unrelated columns (colour=last_name), but for vast majority of cases, when joining, one of the side should be joined using it’s unique key, and other side should be using it’s foreign key, which ensures that duplicates don’t appear randomly, and thus distinct is not needed.
If for ten years you always indented the code this way
Void F()
{ Foo();
Bar();
Baz();}
Void F()
{
Foo();
Bar();
Baz();
}
> The parameter must not escape the function call (e.g. by being assigned to a global variable). Ignored for any parameter that is not a reference type.
https://dlang.org/spec/function.html#scope-parameters
See also: https://dlang.org/blog/2023/10/02/crafting-self-evident-code... , https://news.ycombinator.com/item?id=37748543
> I suspect the same thing would be true for attempts to develop AGI...
On the other hand, I would not be surprised if this did _not_ generalize and translate to LLMs. Biological entities on earth tend to have tons of fairly arbitrary developmental legacy which may or may not translate well to an artificial one. In the experiment, they didn't make billions of clones of the cat with a variety of different parameters and check which one worked, they just observed that yes, this standard v1 cat has some specific hard-wired developmental tendencies. It is not surprising that taking it out of the environment it was evolved for messes things up, but I would not take the extra step that this means that something is essential in general.
I guess that's similar to the redis example I gave, but it essentially means that even though we get sent JSON over the wire, we validate it fully and when it gets to our code we know it's a well formatted type. So our code can assume an email type is a valid email, an ID type is a valid ID, etc.
I saw similar, catchy phrase: “parse, don’t validate”.
https://lexi-lambda.github.io/blog/2019/11/05/parse-don-t-va...
You could even create an equilibrium level (probably more theoretic than practical at the population levels in modern times, but not necessarily in ancient) where this group's fertility trends up end perfectly balancing against the rest of South Korea's low fertility trends, such that the population doesn't even meaningfully change, or maybe even increases, yet the DNA pool ends up near to 100% controlled by a tiny minority. I'm curious if and how this would look different (from a long distant DNA analysis) from the suggestion that suddenly all of South Korea just mysteriously died and these were the only people left.
Also, I don't vote so the politicians are the responsibility of people who mistakenly believe their vote matters when they are selectively stolen, gerrymandered, and manufactured consent into futility. 45 may have tried to steal Georgia like a moron, but Bernie lost the 2016 WV primary even though every district voted for him as the consequence of that state's electors collusion with one candidate. Until there's sortition, campaign finance reform, or an emperor, NPVIC could eventually be a potential workaround for electoral mutinies.
Until then, there's not much chance of change because the only viable candidates are celebrities and career politicians willing to bend the knee to big money donors in exchange for favor$.
Not if distinct is the default.
> Select distinct student.student_name, parent.parent_name from student join parent on student.parent_id = parent.parent_id —- silently discards rows, where by accident student/parent name combo matches several times.
Either with or without distinct can be a bug depending on what you are doing it for.
There are actually 4 variations on what you might want, and you can get all of them with distinct:
> Not if distinct is the default.
If that works for you, great, but let’s agree to disagree here.