Most active commenters

    ←back to thread

    MVCC – the part of PostgreSQL we hate the most (2023)

    (www.cs.cmu.edu)
    366 points virtualwhys | 13 comments | 20 Oct 24 15:30 UTC | HN request time: 0.624s | source | bottom
    Show context
    fweimer ◴[20 Oct 24 18:48 UTC] No.41897588[source]▶
    The big advantage is that you do not need any extra space if your workload mostly consists of INSERTs (followed by table drops). And it's generally unnecessary to split up insertion transactions because there is no size limit as such (neither on the generated data or the total count of rows changed). There is a limit on statements in a transaction, but you can sidestep that by using COPY FROM if you do not have to switch tables too frequently. From a DBA point of view, there is no need to manage a rollback/undo space separately from table storage.

    Every application is a bit different, but it's not that the PostgreSQL design is a loser in all regards. It's not like bubble sort.

    replies(4): >>41897732 #>>41902493 #>>41904079 #>>41905601 #
    1. indulona ◴[20 Oct 24 19:09 UTC] No.41897732[source]▶
    > but it's not that the PostgreSQL design is a loser in all regards

    the article literally says that pg's mvcc design is from the 90s and no one does it like that any more. that is technology that is outdated by over 30 years. i'd say it does not make it a loser in all regards, but in the most important aspects.

    replies(4): >>41898162 #>>41898235 #>>41898303 #>>41902986 #
    2. naranha ◴[20 Oct 24 20:14 UTC] No.41898162[source]▶
    At least couchdb is also append only with vacuum. So it's maybe not completely outdated.
    replies(1): >>41898658 #
    3. mikeocool ◴[20 Oct 24 20:29 UTC] No.41898235[source]▶
    When it comes to your data store, some people might consider using technology that’s been reliably used in production by many organizations for 30 years a feature not a bug.

    I’d prefer not to be the first person running up against a limit or discovering a bug in my DB software.

    replies(2): >>41898511 #>>41908322 #
    4. kunley ◴[20 Oct 24 20:43 UTC] No.41898303[source]▶
    Still I am very happy to use every day the technology designed in early 70s by Ken Thompson and colleagues, so far in that specific field many tried to invent something more "modern" and "better" and failed, with an exception of a certain Finnish clone of that tech, also started in 80s by the way.

    So, newer not always means better, just saying

    replies(3): >>41899219 #>>41899463 #>>41907434 #
    5. mannyv ◴[20 Oct 24 21:12 UTC] No.41898511[source]▶
    Well every product has issues. The question is, do you feel like dealing with those issues or not?

    Flat files have also been reliably used in production for decades. That doesn't mean they're ideal...although amusingly enough s3 and its equivalent of flat files is what we've migrated to as a data store.

    replies(1): >>41908961 #
    6. jbellis ◴[20 Oct 24 21:33 UTC] No.41898658[source]▶
    High performance has never been a reason to use couchdb.
    7. nine_k ◴[20 Oct 24 23:05 UTC] No.41899219[source]▶
    Speaking of which, if you try an actual System V in an emulator, or look at C code in K&R style, certain progress, as in "much more actually usable", can be noticed.

    While persisting key architectural ideas certainly has benefits, so does evolving their implementations.

    8. throwawayie6 ◴[20 Oct 24 23:42 UTC] No.41899463[source]▶
    > exception of a certain Finnish clone of that tech

    Are you referring to C++? That was actually created by a Danish guy, who was also inspired by the object oriented Simula language created in the 60s

    replies(1): >>41899553 #
    9. nneonneo ◴[21 Oct 24 00:04 UTC] No.41899553{3}[source]▶
    Pretty sure the OP was referring to UNIX and its “Finnish clone” Linux.
    10. j16sdiz ◴[21 Oct 24 11:29 UTC] No.41902986[source]▶
    > the article literally says that pg's mvcc design is from the 90s and...

    Actually, it is 1980s. The article:

    > Its design is a relic of the 1980s and before the proliferation of log-structured system patterns from the 1990s.

    11. gregw2 ◴[21 Oct 24 19:18 UTC] No.41907434[source]▶
    Err, Linux is a child of the 90s...

    Linus began work on it in April 1991: https://groups.google.com/g/comp.os.minix/c/dlNtH7RRrGA/m/_R...

    12. simne ◴[21 Oct 24 20:40 UTC] No.41908322[source]▶
    Tell this to developers of Ariane 5, who used old proven software from Ariane 4.

    Many people consider this most expensive bug in history, when on first flight of Ariane 5, it enters speed range, which was hard prohibited in Ariane 4 software and caused software exception and then 1 billion crashed.

    Honesty, they could re-check all ranges, but they decided, it would cost like write new software, so to save money, was made decision to just use old software, without additional checks.

    13. diroussel ◴[21 Oct 24 21:59 UTC] No.41908961{3}[source]▶
    It would be quite nice to have some of the S3 semantics on local files. Like no one else can the see the file until after you’ve finished writing the file and committed it. And being able to put almost any chara in the file name (key). That is quite nice in S3