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Are you aware: 1. That PgSQL also has issues in jepsen tests? 2. of any distributed DB which doesn't have jepsen issues? 3. It is configurable behavior for M

Are you aware: 1. That PgSQL also has issues in jepsen tests? 2. of any distributed DB which doesn't have jepsen issues? 3. It is configurable behavior for MongoDB: can it lose data and work fast, or work slower and do not lose data. There is no issues of unintentional data loss in most recent(5yo) jepsen report for MongoDB.

jwr 2y ago
Distributed databases are not easy. You can't simplify everything down to "has issues". Yes, I did read most Jepsen reports in detail, and struggled to understand everything. Your second point seems to imply that everything has issues, so using MongoDB is fine. But there are various kinds of problems. Take a look at the report for RethinkDB, for example, and compare the issues found there to the MongoDB problems.
- riku_iki 2y ago
  > Take a look at the report for RethinkDB RethinkDB doesn't support cross document transactions, problem solved lol
theamk 2y ago
PgSQL only defect was anomaly in reads which caused transaction results to appear a tiny bit later, and they even mentioned that it is allowed by standards. No data loss of any kind. MongoDB defects were, let's say, somewhat more severe [2.4.3] "In this post, we’ll see MongoDB drop a phenomenal amount of data." [2.6.7] "Mongo’s consistency model is broken by design: not only can “strictly consistent” reads see stale versions of documents, but they can also return garbage data from writes that never should have occurred. [...] almost all write concern levels allow data loss. [3.6.4] "with MongoDB’s default consistency levels, CC sessions fail to provide the claimed invariants" [4.2.6] "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" let's not pretend that Mongo is a reliable database please. Fast? likely. But if you value your data, don't use it.
- riku_iki 2y ago
  In attempt to understand your motives in this discussion, I would like to ask question: * why you are referring on 12yo reports for very early MongoDB version?
  - jwr 2y ago
    This discussion refers to the entire history of MongoDB reports, which shows a lack of care about losing data. If you wish to have a more recent MongoDB report, Jepsen is available for hire, from what I understand.
    - riku_iki 2y ago
      No, discussion started with question "Why choose Mongo in 2025?" So, old jepsen reports are irrelevant, and most recent one from 2020 is somehow relevant.

jwr 2y ago

Distributed databases are not easy. You can't simplify everything down to "has issues". Yes, I did read most Jepsen reports in detail, and struggled to understand everything. Your second point seems to imply that everything has issues, so using MongoDB is fine. But there are various kinds of problems. Take a look at the report for RethinkDB, for example, and compare the issues found there to the MongoDB problems.

riku_iki 2y ago
> Take a look at the report for RethinkDB RethinkDB doesn't support cross document transactions, problem solved lol

theamk 2y ago

PgSQL only defect was anomaly in reads which caused transaction results to appear a tiny bit later, and they even mentioned that it is allowed by standards. No data loss of any kind. MongoDB defects were, let's say, somewhat more severe [2.4.3] "In this post, we’ll see MongoDB drop a phenomenal amount of data." [2.6.7] "Mongo’s consistency model is broken by design: not only can “strictly consistent” reads see stale versions of documents, but they can also return garbage data from writes that never should have occurred. [...] almost all write concern levels allow data loss. [3.6.4] "with MongoDB’s default consistency levels, CC sessions fail to provide the claimed invariants" [4.2.6] "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" let's not pretend that Mongo is a reliable database please. Fast? likely. But if you value your data, don't use it.

riku_iki 2y ago
In attempt to understand your motives in this discussion, I would like to ask question: * why you are referring on 12yo reports for very early MongoDB version?
- jwr 2y ago
  This discussion refers to the entire history of MongoDB reports, which shows a lack of care about losing data. If you wish to have a more recent MongoDB report, Jepsen is available for hire, from what I understand.
  - riku_iki 2y ago
    No, discussion started with question "Why choose Mongo in 2025?" So, old jepsen reports are irrelevant, and most recent one from 2020 is somehow relevant.