PostgreSQL Parallel Aggregate
At last! This was the only feature I was missing in Postgres for years.<p>Postgres is so amazing I still find it hard to believe it's free. I abused it many times (as a graph database; as a real-time financial data analytics engine with thousands of new ticks coming in each second; as a document storage with several TBs of data per node), and amazingly, it just worked. Magic.<p>If in doubt, choose Postgres.