Never going down in a database doesn't just mean that it doesn't have downtime, it also means that as a whole system it's immune to bad queries. Bad queries ca

Never going down in a database doesn't just mean that it doesn't have downtime, it also means that as a whole system it's immune to bad queries. Bad queries can destroy you in MySQL, if you are doing dynamically created queries that hit un-optimized areas, it can bring down all the other queries too. I'd typically use Memcache with MySQL too, so there isn't any real difference in that case. One use case I like SimpleDb for is for small scripts that need a very simple data store.