db={"user":[{_id:1,name:"Noah",city_id:2,job_id:3},{_id:2,name:"Oliver",city_id:2,job_id:1},{_id:3,name:"William",city_id:1,job_id:3}],"city":[{_id:1,name:"Tokyo"},{_id:2,name:"Mexico City"},{_id:3,name:"Los Angeles"}],"job":[{_id:1,title:"Architect"},{_id:2,title:"Barista"},{_id:3,title:"Farmer"}]}

db.city.aggregate([{$lookup:{from:"user",localField:"_id",foreignField:"city_id",as:"users",pipeline:[{$lookup:{from:"job",localField:"job_id",foreignField:"_id",as:"jobs"}}]}}])