Oracle has very goog technology for large corporations
I do not support they arrogant treatment of customers and out of this world pricey licensing, but for large customers like Amazon. Oracle might be the sweetspot:
I once knew a DBA that single-handedly managed 425 oracle databases on 2 exadatas, with full redundancy and rollback, rollforward and multitiered backup in seconds on mirrored raid. I've never been given so good support. And we had to support oracle instead of mysql beacause to the cost of having a mysql dba and percona support was higher than using a better SLA with exadata.