A wonderful read for anyone looking to learn about sharding. However, the Final Thoughts section is probably the most important: don't do it unless you have to. Sharding is a pain and will severely limit your ability to develop new features quickly and for many sites, sharding will never be needed (since they won't grow that big). Databases are efficient and hardware is fast. Sometimes your user-base is larger than what those great things can handle so it's good to know what sharding is, but it isn't fun to do so avoid it if you don't need it.