In February 2017, we discussed data loss and fixes in MongoDB 3.4.0-rc3’s v0 and v1 replication protocols. In this Jepsen report, we will verify that MongoDB 3.6.4’s sharded clusters offer comparable safety to non-sharded deployments. We’ll also discuss MongoDB’s new support for causal consistency (CC) in version 3.6.4 and 4.0.0-rc1, and show that sessions prevent anomalies so long as user stick t