But not everything we do in a database needs guaranteed transactional consistency. Imagine you are charged with designing a system to collect data on temperature, air flow and electricity use in a building every few minutes from hundreds of locations. The system will be used to make the building more energy efficient. Now imagine you lose a few data points every day. The cause isn't important but it could be a glitch with a sensor, a dropped packet, or an incomplete write operation in the database. Do you care?
via NoSQL databases