Say we have a social media app where users can post their content something similar to facebook or linkedin posts. We need to basically count the number of likes/views received by the post in real time. Need to handle all possible cases and design the best possible efficient system. Cases like a post can go viral and might receive billions of likes/views or some posts which might receive very few likes. Need to design an efficient system so that users can be updated with these numbers in real time as quickly as possible.