Comment by arinlen | Hacker News Reader

Comment by arinlen | Hacker News Reader

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> Yes, Jepsen did find some issues with the initial release of ACID transactions (...)

By "some issues" you mean lost data and violated causal by default.

https://www.infoq.com/news/2020/05/Jepsen-MongoDB-4-2-6/

And no, the issues were not fixed. Jepsen pointed out that "the newer MongoDB 4.2.6 has more problems" including “retrocausal transactions”.

https://jepsen.io/analyses/mongodb-4.2.6

From Jepsen's report:

> Jepsen evaluated MongoDB version 4.2.6, and found that even at the strongest levels of read and write concern, it failed to preserve snapshot isolation. Instead, Jepsen observed read skew, cyclic information flow, duplicate writes, and internal consistency violations.

Also read the addendum from the same report:

1 Updates 2020-05-26: MongoDB identified a bug in the transaction retry mechanism which they believe was responsible for the anomalies observed in this report; a patch is scheduled for 4.2.8.

> Also read the addendum from the same report:

Your initial claim was that these issues were addressed in 4.0.

Jepsen's report refutes your claim,and demonstrates MongoDB had serious reliability problems even in 4.2.6.

Frankly, your insistence in pulling the wool over everyone's eyes, specially on a topic that's easily verified, does not help built up trust on MongoDB

I can see the source of confusion. Apologies. I mentioned ACID transactions were released in 4.0 but did not explicitly mention when the problems arose which of course was in 4.2 which was actually released a year later. The version numbers are clearly referenced in the Jepsen article.

Another take https://arxiv.org/pdf/2111.14946.pdf

This is the core culture of MongoDB - cutting corners to optimise things a little more and cater to a NoSQL crowd. It's entire mindset is fundamentally different from what you'd get in a proper relational database and ignoring those things isn't going to do any software you write any favours.

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