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How Postgres Makes Transactions Atomic (2017)
- rosser 7y agoSubmitter, or a moderator, please edit the title to re-add the word "How". That's done automatically, but sometimes it's wrong. It's especially so here. Also, this remains as fantastic an article on PostgreSQL's MVCC nature as it was previously: https://news.ycombinator.com/item?id=15027870 https://news.ycombinator.com/item?id=15027870
- draw_down 7y agoI've noticed that too. In what cases is that useful? It seems unnecessary and actively harmful at times, like in this case.
- kbenson 7y ago> In what cases is that useful? Edit: whoops, I thought you were replying to the request to add 2017 to the title. If you've possibly already read it and are wondering if it's a repeat, if you have knowledge that the topic has had changes since then which might make it less accurate, and any number of other things. In the end, it's more information, if people want to assume something negative about it, I feel that's on them (as long as the information shown is accurate).
- pushpop 7y agoI feel you’re talking about the date in brackets, which most people agree is useful. However the GP is discussing a different behaviour on HN where the word “How” is automatically dropped from headlines when it is used as a prefix. This behaviour doesn’t provide more information, as you state, though your opinion of its desirability might still differ from the GPs.
- kbenson 7y agoYeah, I noticed that myself a bit ago, and edited my comment. You're correct in that I was talking about the date. Thread comprehension fail on my part. :)
- Deimorz 7y agoIt's a very common style of headlines recently, and a lot of the time you can remove the "How" without changing the meaning. For example, if I look down The Verge's recent posts, the first one starting with "How" is "How sampling and streaming are changing the future of music" [1]. Titling that "Sampling and streaming are changing the future of music" works fine. I don't know that it's particularly useful most of the time, it's usually just unnecessary. An example where it actually should have been removed that I remember was this article on The Guardian a while back: "Suburb in the sky: how Jakartans built an entire village on top of a mall" [2]. There's nothing in the article at all about how they built it. It's just a trendy headline style for some reason, and gets used even in cases where it doesn't apply, like that one. [1]: https://www.theverge.com/2019/9/17/20870347/sampling-streaming-despacito-charli-xcx-music-dani-deahl-future-of-music-vergecast https://www.theverge.com/2019/9/17/20870347/sampling-streami... [2]: https://www.theguardian.com/cities/2019/aug/05/suburb-in-the-sky-how-jakartans-built-an-entire-village-on-top-of-a-mall https://www.theguardian.com/cities/2019/aug/05/suburb-in-the...
- thom 7y agoPerhaps this cheapening of the word 'how' explains the prevalence of the academic literary tic 'the manner in which' in its place.
- Deimorz 7y agoAlso, add "(2017)".
- dmitryminkovsky 7y agoThanks, done
- dmitryminkovsky 7y agoThanks. Missed that.
- sarah180 7y agoThe "How" at the beginning of the title is important: this is clickbait without it.
- jonas21 7y agoWhen you submit a title that begins with "How", HN automatically removes the "How" -- ironically, as an attempt to avoid clickbait.
- kfrzcode 7y agoHow is it clickbait rather than just a less than precise a description of the material?
- ghusbands 7y agoAs a headline, "Postgres Makes Transactions Atomic" would be read by many as being a new feature. Adding "How" removes that reading.
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- teej 7y agoFrom the previous discussion, I discovered that the author used Monodraw to create the diagrams. I'm excited to check it out - https://monodraw.helftone.com/ https://monodraw.helftone.com/
- onemoresoop 7y agoMac only?
- romaniitedomum 7y agoIt's a minor typo, but in the first paragraph under the heading Defensive programming this sentence occurs: > I won’t go into subcommits in any detail, but it’s worth nothing that because TransactionIdCommitTree cannot be guaranteed to be atomic From the context I think the word "nothing" should be "noting", as in, "It's worth noting".
- bgentry 7y agoAuthor accepts PRs via GitHub :) https://github.com/brandur/sorg/blob/master/content/articles/postgres-atomicity.md https://github.com/brandur/sorg/blob/master/content/articles...
- _pmf_ 7y agoInterested in how the author created the images; they have a beautiful, clear retro look.
- ololobus 7y agoAFAIK Brandur uses Monodraw [1]. It's so cool, I even purchased a license for myself, although the author of the app stopped its active development [2]. [1] https://monodraw.helftone.com/ https://monodraw.helftone.com/ [2] https://blog.helftone.com/monodraw-maintenance-mode/ https://blog.helftone.com/monodraw-maintenance-mode/
- del_operator 7y agoInteresting coincidence that early yesterday I found this blog when searching for transaction patterns. I skimmed the transactions for idempotent apis (2017) and its part ii. Hadn’t heard of it before but liked the diagrams
- yvan 7y agoIt might be a newbie question, but for my own culture, what is the impact of a given snapshot if the database is really big ? I guess it all depends on what data we are touching, but let imagine I want to update all the rows for a table with 1 billions entries, wouldn't the snapshot be giantic ? Or maybe I misunderstood what is a snapshot.
- petereisentraut 7y agoA snapshot is actually just a struct with a few transaction IDs (xids) and some other bookkeeping that describes which slice of the physically stored data is supposed to be visible to a transaction. The article shows the details of that. So the size of a snapshot is unrelated to the size of the database.
- yvan 7y agoThanks for the information. I read the article but didn't understand it well.