In ~which venue~ did you taste the most beers?
db.beer.aggregate( [
{ '$group' : {
'_id' : '$venue_name',
'count' : { '$sum' : 1 },
} },
{ '$sort' : { 'count' : 1 } },
{ '$limit' : 1 },
] ).pretty()
Result:
{ "_id" : "Euston Cider Tap", "count" : 217 }