Which DB? SQL vs NoSQL

[Revanth]

I have read that high traffic sites such as Twitter uses MySQL as their DB. If a complex service like Twitter uses MySQL as their DB without any issue, why cant we use a SQL DB solution for this url shortening service?

Please explain in detail about sharding data in SQL solution

[Bilall]

Generally, these companies use both SQL and NoSQL based systems together for different purposes. So no single bullet for all purposes.