> This is exactly a great point. When data size goes to a billion rows, Postgres is tough. MongoDB just works without issue.

Personally, I've not seen any application that seriously needs a billion rows in a single table. (except at truly massive scale, but then you're not using Mongo)

The real solution is implementing archiving to a file store like S3 and/or ship it off to a data warehouse. You don't need billions of rows in a `record_history`/`user_audit` table going back 5 years in your production database. Nobody queries the data.