Chapter 5: Indexing and Aggregation Pipeline

Im not so sure I understand what listings I have to check in Chapter 5? It says this:
2. Which countries have listings in the sample_airbnb database? I can’t find countries nor listings, they are looking for.

What collections do you have in the sample_airbnb database?

In my case, I have the collection listingAndReviews. When I analyze the schema with Compass, I see that some documents have a field named address which is an Object with a sub-field named country.

Okay, I can find a country inside address list, what about this listing? What do I have to check?

From the following information:

  1. there is only one collection in the database sample_airbnb ,
  2. this collection is called listingsAndReviews.
  3. documents in this collection have a field named listing_url ,
  4. documents in this collection have a field named reviews ,
  5. documents in this collection have an object field named address which contains a sub-field named country

I assume that by Which countries have listings in the sample_airbnb database?, they mean, what are the different values of the country sub-field in the documents in the listingsAndReviews collection?