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Comment on How does this pic show that Elon Musk doesnt know SQL?

KillingTimeItself@lemmy.dbzer0.com ⁨6⁩ ⁨days⁩ ago

TL;DR de-deuplication in that form is used to refer a technique where you reference two different pieces of data in the file system, with one single piece of data on the drive, the intention being to optimize file storage size, and minimize fragmentation.

You can imagine this would be very useful when taking backups for instance, we call this a “Copy on Write” approach, since generally it works by copying the existing file to a second reference point, where you can then add an edit on top of the original file, while retaining 100% of the original file size, and both copies of the file (its more complicated than this obviously, but you get the idea)

now just to be clear, if you did implement this into a DB, which you could do fairly trivially, this would change nothing about the DB operates, it wouldn’t remove “duplicates” it would only coalesce duplicate data into one single tree to optimize disk usage. I have no clue what elon thinks it does.

The problem here, as a non programmer, is that i don’t understand why you would ever de-duplicate a database. Maybe there’s a reason to do it, but i genuinely cannot think of a single instance where you would want to delete one entry, and replace it with a reference to another, or what elon is implying here (remove “duplicate” entries, however that’s supposed to work)

Elon doesn’t know what “de-duplication” is, and i don’t know why you would ever want that in a DB, seems like a really good way to explode everything,

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valtia@lemmy.world ⁨5⁩ ⁨days⁩ ago

i genuinely cannot think of a single instance where you would want to delete one entry, and replace it with a reference to another

Well, there’s not always a benefit to keeping historical data. Sometimes you only want the most up-to-date information in a particular table or database, so you’d just update the row (replace). It depends on the use case of a given table.

what elon is implying here (remove “duplicate” entries, however that’s supposed to work)

Elon believes that each row in a table should be unique based on the SSN only, so a given SSN should appear only once with the person’s name and details on it. Yes, it’s an extremely dumb idea, but he’s a famously stupid person.

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- KillingTimeItself@lemmy.dbzer0.com ⁨5⁩ ⁨days⁩ ago
  
  Well, there’s not always a benefit to keeping historical data. Sometimes you only want the most up-to-date information in a particular table or database, so you’d just update the row (replace). It depends on the use case of a given table.
  
  in this case you would just overwrite the existing row, you wouldn’t use de-duplication because it would do the opposite of what you wanted in that case. Maybe even use historical backups or CoW to retain that kind of data.
  
  Elon believes that each row in a table should be unique based on the SSN only, so a given SSN should appear only once with the person’s name and details on it. Yes, it’s an extremely dumb idea, but he’s a famously stupid person.
  
  and naturally, he doesn’t know what the term “de-duplication” means. Definitionally, the actual identity of the person MUST be unique, otherwise you’re going to somehow return two rows, when you call one, which is functionally impossible given how a DB is designed.
  
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  - valtia@lemmy.world ⁨5⁩ ⁨days⁩ ago
    
    in this case you would just overwrite the existing row, you wouldn’t use de-duplication because it would do the opposite of what you wanted in that case.
    
    … That’s what I said, you’d just update the row, i.e. replace the existing data, i.e. overwrite what’s already there
    
    Definitionally, the actual identity of the person MUST be unique, otherwise you’re going to somehow return two rows, when you call one, which is functionally impossible given how a DB is designed.
    
    … I don’t think you understand how modern databases are designed
    
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    KillingTimeItself@lemmy.dbzer0.com ⁨5⁩ ⁨days⁩ ago
    
    … That’s what I said, you’d just update the row, i.e. replace the existing data, i.e. overwrite what’s already there
    
    u were talking about not keeping historical data, which is one of the proposed reasons you would have “duplicate” entries, i was just clarifying that.
    
    … I don’t think you understand how modern databases are designed
    
    it’s my understanding that when it comes to storing data that it shouldn’t be possible to have two independent stores of the exact same thing, in two separate places, you could have duplicate data entries, but that’s irrelevant to the discussion of de-duplication aside from data consolidation. Which i don’t imagine is an intended usecase for a DB. Considering that you literally already have one identical entry. Of course you could simply make it non identical, that goes without saying.
    
    Also, we’re talking about the DB used for the social security database, not fucking tigerbeetle.
    
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- DacoTaco@lemmy.world ⁨5⁩ ⁨days⁩ ago
  Ssn being unique isnt a dump idea, its a very smart idea, but due to the us ssn format its impossible to do. Hence to implement the idea you need to change the ssn format so it is unique before then.
  
  Also, elons remark is stupid as is. Im sure the row has a unique id, even if its just a rowid column.
  
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  - KillingTimeItself@lemmy.dbzer0.com ⁨5⁩ ⁨days⁩ ago
    
    Also, elons remark is stupid as is. Im sure the row has a unique id, even if its just a rowid column.
    
    even then, i wonder if there’s some sort of “row has function” that takes a hash of all the data in a single entry, and generates a universally unique hash of that entry, as a form of “global id”
    
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