Which of the following is not an aggregation operation? (choose all that apply)

The following statement is most suitable for aggregation stage: 'Used to select fields from the collection while aggregation'.

Which statement best describes $allElementsTrue?

All the replica set members contain a copy of the oplog in the _____ collection.

Which could be a use case where MongoDB is a good fit?

If you created a compound index on (X, Y, Z), which access pattern will not be able to utilize the index?

What is command specifying for database path ?

Asume a users collections with the following fields: "_id", "username", "password", "email". At least one of the users has registered all of the fields. If you run both this queries: 1) db.users.find({}, {password: false, email: false}); 2) db.users.find({}, {_id: false, username: true}) Would the output be the same?

Suppose you have a collection foo with an index created using the statement db.foo.ensureIndex({a:1, b:-1, c:1}). Which of the following queries could use the index

By default, MongoDB allows up to _____ collections.

Haystack Indexes are typically used to: