Please explain what should be done - mongoshell throws error but no idea as error so general.
db.listingsAndReviews.aggregate([
{$project: {“address”:1,"_id":0 }},
{$group: {"_id":"$address.country"}}, // comment : good to here so next step… just sum
{$group: {"_id":null, count:{$sum:1}}
])
So having a smaller number of ‘documents’ … now how to transform that ?