<i>Currently MongoDB is outperformed by Postgres</i><p>I hate hearing absolutist dogma like this. Some things are faster in Postgres, some things are faster in Mongo. We are migrating our analytics db from Mongo to PG but we hit a wall because SELECT COUNT(DISTINCT x)) performs abysmally in Postgres. Mongo&#x27;s aggregation framework is an immature PITA but it performs this little trick well enough that we&#x27;re pretty much stuck keeping Mongo around unless we want to use MSSQL or Oracle or something else with a better (and much more expensive) query planner.<p>We still love (and prefer) Postgres but it is not a pareto improvement. There are always tradeoffs, and this kind of fanboyism just speaks to inexperience.