Question: Given a customer collection which includes fields for gender and city, which aggregate pipeline shows the number of female customers in each city? (_Alternative_: How can you view the execution performance statistics for a query?)
- `db.members.aggregate([ {$match: {gender: "Female"}}, {$group: {_id: {city: "$city"}, number: {$sum: 1}}}, {$sort :{number: -1}}])`
- `db.members.find({$match: {gender: "Female"}}, {$group: {_id: {city: "$city"}, number: {$sum: 1}}}.$sort ({number: -1})`
- `db.members.find([ {$match: {gender: "Female"}}, {$group: {_id: {city: "$city"}, number: {$sum: 1}}}, {$sort :{number: -1}}])`
- `db.members.aggregate([ {$match: {gender: "Female"}}, {$sort :{number: -1}}])`
Answer: The correct answer of the above question is Option A:`db.members.aggregate([ {$match: {gender: "Female"}}, {$group: {_id: {city: "$city"}, number: {$sum: 1}}}, {$sort :{number: -1}}])`