No, it's not just that simple. Parallel seqscan is in 9.6, true, but parallel aggregation needs a bunch of things on top of that. You can't just compute aggrega

No, it's not just that simple. Parallel seqscan is in 9.6, true, but parallel aggregation needs a bunch of things on top of that. You can't just compute aggregations in parallel and expect meaningful results - several workers might end up computing data for the same group. So there needs to be logic to re-aggregate. Nothing impossible, but also nothing done in 5 minutes.