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Re:MongoDB queries don’t always return all matching documents by threeseed on Tuesday June 07, 2016 @07:39PM (#11858932)
Cassandra, HBase etc had checkered pasts with plenty of their own data loss and inconsistency bugs.

Now they are considered two of the most rock solid NoSQL databases. The hatred towards MongoDB really is pretty irrational given just how popular the database is.

Re:MongoDB queries don’t always return all matching documents by chaostheory on Tuesday June 07, 2016 @10:12PM (#11859543)
It is anything but irrational.

https://aphyr.com/posts/322-jepsen-mongodb-stale-reads

If it isn't already fixed, they need to fix it. I can't vouch for HBase, but Cassandra is stable and reliable now. Cassandra is also easier to scale.

Re:MongoDB queries don’t always return all matching documents by im_down_w_otp on Tuesday June 07, 2016 @10:35PM (#11859611)
FWIW, I don't think Cassandra is particularly any better today semantically than it used to be. Merge conflicts are still at the cell level than the row level, and wall-clock time is still the way that LWW resolution is determined. It let's you mix strongly consistent and eventually consistent data together, which makes no sense.

But the difference is that Cassandra is reliably "broken" in those ways, and as a result there are ways of using it which don't lean heavily on those weaknesses. Such as writing only immutable data or isolating all data that will be used in paxos transactions into their own column families by convention, etc.

Cassandra more or less behaves exactly as it claims that it does. So you can do a somewhat thorough investigation of its system semantics and know what you can rely on and what you can't. MongoDB doesn't even uphold the system semantics it claims that it has, so it's just broken in weird and esoteric ways that you discover mostly by accident.