Good luck trying to show the number of likes in twitter, instagram, face, Kardashian's tinder... Any query that needs to calculate some result and has many row

Good luck trying to show the number of likes in twitter, instagram, face, Kardashian's tinder... Any query that needs to calculate some result and has many rows benefit from storing pre-calculated values. With a trade-off in precision, correctness, and so on. Might apply to your business or not.