MongoDB found a bug in the retry mechanism which they think is responsible for the issues we found in 4.2.6--a fix is scheduled for 4.2.8!
MongoDB rewrote their Jepsen page, but it still goes to great lengths to avoid talking about write loss or aborted reads, both of which are the default behavior:
I keep thinking about their VLDB paper which says ~80% of writes to MongoDB's hosted service don't set a write concern, and 99.6% of reads don't set a read concern. http://www.vldb.org/pvldb/vol12/p2071-schultz.pdf
I called this out in the report as well, but the write concern documentation still doesn't say anything about rollbacks/write loss: https://docs.mongodb.com/manual/reference/write-concern/
A single-user Mastodon instance for Jepsen announcements & discussion.