I'm a bit confused because I'm questioning the definition of 'online' in OLTP and OLAP. I used to think that 'online' here means that we want our answer in bounded time and based on the data available at an instance in time.
But OLAP queries can take a some hours to compute - isn't this offline?
And a quick search indicates offline OLAP which sounds rather confusing (offline online analytical processing)...?
What exactly is 'online'?