Hacker News Reader

I wonder if it's possible that it was a MongoDB glitch and not a user error. From what I've read, it's notorious for randomly losing records. Maybe the loop save triggered it?

View on HN

I definitely don't attribute this to MongoDB (or MongoEngine or pymongo or Django). I haven't seen it lose any of our documents to date. Silently dropping documents when saving them without making any changes would be a huge problem. It's astronomically unlikely.

Maybe something in the Mongo-ORM layer went wrong, so you were iterating over empty models, and then saving them back. Could that have created the absences seen later? (The way you talk about your client automatically fixing things on the load/save cycle suggests you might have some magic there.)

It just seems hard to believe you confused 'save' and 'delete'...

I'm pretty sure nothing fishy went on behind the scenes. The client "automatically" fixes things through our API when it tries to log in because it will create an account if it doesn't exist.

I, too, have a hard time believing I confused "save" and "delete", but I'm reasonably sure that's what happened. I think I misused Python's shell history. I'll bet I hit the up arrow, which resurrected "family.delete()" instead of "family.save()".

Reply on news.ycombinator.com