I'm writing an online appointment system. I've come across to heard about the MongoDB. I've been told that insert and query operation will be faster in MongoDB. is it true? For my application, insertion is crucial(users will book their appoints online, that means- tons of insert) as well as query (to check is the slot is available).

Can you please help me to come up with the decision on choosing the right database for my application. What might be the advantage/disadvantage of using MongoDB over MySQL.

Thanks in advance.