2. MySQL is good for traditional associations where they are required, MongoDB is more used for Logging, SNS, and other K-V based needs, but both databases are actually capable of handling most of these needs.

For MongoDB, associations are generally made inline to maximize their benefits.

3. You can consider using MongoDB for new projects if you are inexperienced and short on time, then you can continue to use MySQL

4. In short, the right tool for the right task

5. MongoDB has a relatively good scalability and can be easily made into a distributed architecture

6. MongoDB has good scalability and can easily be made into a distributed architecture

6. For MongoDB, the more memory, the better

7.