I then asked if it was fine or if I was going to find corruption when I tried to read it, and they suggested I do db.repairDatabase() to rebuild everything. No sooner said than done, I ran the command and left it for a few hours to run. At some point I lost my SSH connection to the server but thought that it would probably keep running or, at least, leave the database in some half-consistent state so I could rerun the query. That’s exactly what it did, but it also deleted 90% of my data, which I couldn’t recover.

In summary, I would not let MongoDB near my children, let alone run it on a production environment (or even a testing one). It’s a great piece of software when it works, but that’s not very often. A database that doesn’t really store data is very, very dangerous.