A social media company needs to implement a data model that describes te relationships between users. When loading real data into the system, it turned out that one user has too many contacts to store them in the designated array. Instead of redesigning the entire system what pattern can you use?

Select all true statements regarding to scaling.

Suppose you want to join two collections in the same database. What aggregation stage do you need to use?

Where is collection metadata stored in a sharded cluster?

Select all true statements about chunks in MongoDB.