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MongoDB vs. PostgreSQL vs. ScyllaDB: Tractian’s Experience

• winrid 3y ago
  But Scylla doesn't offer the same consistency guarantees as Mongo, right? You can shard pretty wide with Mongo and still read your own writes, while my understanding is Scylla is eventually consistent?
  • kinghajj 3y ago
    Scylla has "tunable" consistency[1][2][3], so it's possible to get consistency without too much of a performance hit, and still be resilient to some failures. [1]: https://www.scylladb.com/glossary/eventual-consistency/ https://www.scylladb.com/glossary/eventual-consistency/ [2]: https://docs.scylladb.com/stable/cql/consistency.html https://docs.scylladb.com/stable/cql/consistency.html [3]: https://docs.scylladb.com/stable/cql/consistency-calculator.html https://docs.scylladb.com/stable/cql/consistency-calculator....
    • winrid 3y ago
      Nice, thanks! I haven't used it yet.
    • PeterCorless 3y ago
      On top of this, ScyllaDB also has "Lightweight Transactions" (LWT) that use Paxos to do a compare-and-set (CAS) read-before-write. This is important for strict linearizability. You can think of it really roughly as "single partition ACID." They are also implementing a Raft infrastructure upon which they will be able to do strong consistency transactions in the future. https://www.scylladb.com/tech-talk/the-future-of-consensus-in-scylladb-5-0-and-beyond/ https://www.scylladb.com/tech-talk/the-future-of-consensus-i... [Disclosure: I used to work at ScyllaDB]