Let’s imagine that we have an electronic payment system with the database table operations. For example, we want to calculate the size of average operation. It is easy, here's a query:

SELECT avg(amount) FROM transfer;
generated in 3850 seconds

Now let’s imagine that the index should be the latest one, the entries are made every second in the table, and after a month there are millions of them. To aggregate the same data each time is very expensive. Traditional databases do not offer such optimizations. What to do?
xially 26 march 2012, 15:00