I think the worst part about MongoDB in that timeframe was the poor CPU utilization since it was single threaded. In order to leverage the multiple CPUs in a b

I think the worst part about MongoDB in that timeframe was the poor CPU utilization since it was single threaded. In order to leverage the multiple CPUs in a box you'd need to run multiple instances of mongo on the same machine and we designed a whole system around sandboxing instances. But then you'd run into memory allocation issues and how badly it would handle indexing and handle running out of memory, which mostly involved crashing. We ended up having to run about 100 bare-metal servers to support what would probably have been a level of queries about 10 PostgreSQL boxes could handle easily. Truly a terrible DB.