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A comment on Mongo but on Postgres and with strong consistency benefits. Parent comment

Re:Mongo but on Postgres and with strong consistency benefits by zihotki on Sunday July 07, 2024 @12:08PM (#40898558)
Or is it? Jepsen reported a number of issues like "read skew, cyclic information flow, duplicate writes, and internal consistency violations. Weak defaults meant that transactions could lose writes and allow dirty reads, even downgrading requested safety levels at the database and collection level. Moreover, the snapshot read concern did not guarantee snapshot unless paired with write concern majority—even for read-only transactions."

That report (1) is 4 years old, many things could have changed. But so far any reviewed version was faulty in regards to consistency.

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

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Re:Mongo but on Postgres and with strong consistency benefits by endisneigh on Sunday July 07, 2024 @12:24PM (#40898631)
That’s been resolved for a long time now (not to say that MongoDB is perfect, though).
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Re:Mongo but on Postgres and with strong consistency benefits by nick_ on Sunday July 07, 2024 @03:02PM (#40899658)
I just want to point out that 4 years is not a long time in the context of consistency guarantees of a database engine.

I have listened to Mongo evangelists a few times despite my skepticism and been burned every time. Mongo is way oversold, IMO.

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Re:Mongo but on Postgres and with strong consistency benefits by vorticalbox on Sunday July 07, 2024 @02:20PM (#40899407)
That is for mongo 4.x but latest stable is 6.0.7 which has note More resilient operations and Additional data security.

https://www.mongodb.com/blog/post/big-reasons-upgrade-mongod...

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Re:Mongo but on Postgres and with strong consistency benefits by mmcclimon on Sunday July 07, 2024 @09:31PM (#40901919)
FWIW, the latest stable release is 7.0.12, released a week or so ago: https://www.mongodb.com/docs/upcoming/release-notes/7.0/. (I'm not sure why the URL has /upcoming/ in it, actually: 7.0 is definitely the stable release.)
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Re:Mongo but on Postgres and with strong consistency benefits by pipe_connector on Sunday July 07, 2024 @03:54PM (#40900004)
Jepsen found a more concerning consistency bug than the above results when Postgres 12 was evaluated [1]. Relevant text:

We [...] found that transactions executed with serializable isolation on a single PostgreSQL instance were not, in fact, serializable

I have run Postgres and MongoDB at petabyte scale. Both of them are solid databases that occasionally have bugs in their transaction logic. Any distributed database that is receiving significant development will have bugs like this. Yes, even FoundationDB.

I wouldn't not use Postgres because of this problem, just like I wouldn't not use MongoDB because they had bugs in a new feature. In fact, I'm more likely to trust a company that is paying to consistently have their work reviewed in public.

1. https://jepsen.io/analyses/postgresql-12.3

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