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Jepsen does find stuff with everything. Thus you have to know what is being discussed is serious and blatantly bad, or just the usual "wow distributed is hard".

Jepsen does find stuff with everything. Thus you have to know what is being discussed is serious and blatantly bad, or just the usual "wow distributed is hard". Which is why his papers are so great. But the MongoDB one was "wow this is bad".

threeseed 3y ago
Every distributed database has been "wow this is bad". I assume you have an example of one that wasn't ?
- AtlasBarfed 3y ago
  "MongoDB’s default level of write concern was (and remains) acknowledgement by a single node, which means MongoDB may lose data by default." Cassandra doesn't do that, consistency level is fundamental to the documentation and user guide. That is AWFUL. "Curiously, MongoDB omitted any mention of these findings in their MongoDB and Jepsen page. Instead, that page discusses only passing results, makes no mention of read or write concern, buries the actual report in a footnote, and goes on to claim: MongoDB offers among the strongest data consistency, correctness, and safety guarantees of any database available today. " That is fraud. That is clownshow. Enjoy your increasing revenue.
  - threeseed 3y ago
    The default write concern for the last 2 years has been majority. And single node is a perfectly fine default for most use cases. After all Cassandra's default consistency level is 1.
    - dorlaor 3y ago
      Most users of ScyllaDB/Cassandra use quorum or local_quorum
      - threeseed 3y ago
        And most users of MongoDB use majority write concern. Hence my point there is no difference in defaults between MongoDB and Cassandra.
- doctor_eval 3y ago
  Although it was some time ago and I may be misremembering, I seem to recall reading the Jepsen article on RedPanda and thinking that it (and Postgresql) were among the better reports. Certainly, not all Jepsen reports are all that bad, and tbh I'm at leaast as interested in the way the vendors respond (some of which have been terrible).

threeseed 3y ago

Every distributed database has been "wow this is bad". I assume you have an example of one that wasn't ?

AtlasBarfed 3y ago
"MongoDB’s default level of write concern was (and remains) acknowledgement by a single node, which means MongoDB may lose data by default." Cassandra doesn't do that, consistency level is fundamental to the documentation and user guide. That is AWFUL. "Curiously, MongoDB omitted any mention of these findings in their MongoDB and Jepsen page. Instead, that page discusses only passing results, makes no mention of read or write concern, buries the actual report in a footnote, and goes on to claim: MongoDB offers among the strongest data consistency, correctness, and safety guarantees of any database available today. " That is fraud. That is clownshow. Enjoy your increasing revenue.
- threeseed 3y ago
  The default write concern for the last 2 years has been majority. And single node is a perfectly fine default for most use cases. After all Cassandra's default consistency level is 1.
  - dorlaor 3y ago
    Most users of ScyllaDB/Cassandra use quorum or local_quorum
    - threeseed 3y ago
      And most users of MongoDB use majority write concern. Hence my point there is no difference in defaults between MongoDB and Cassandra.
doctor_eval 3y ago
Although it was some time ago and I may be misremembering, I seem to recall reading the Jepsen article on RedPanda and thinking that it (and Postgresql) were among the better reports. Certainly, not all Jepsen reports are all that bad, and tbh I'm at leaast as interested in the way the vendors respond (some of which have been terrible).