[{"projectName":"Troubleshooting PostgreSQL issues","team":[{"memberId":"cyclops","name":"Cyclops","role":"Postgres Expert"},{"memberId":"wolverine","name":"Wolverine","role":"Consultant"},{"memberId":"storm","name":"Storm","role":"DBA"},{"memberId":"beast","name":"Beast","role":"Developer"},{"memberId":"tony","name":"Tony","role":"Architect"}],"status":"active"},{"projectName":"Build new apps with MongoDB","team":[{"memberId":"tony","name":"Tony","role":"Developer"}],"status":"planned"}]

db.collection.aggregate([{$group:{_id:"$team.memberId",projects:{$push:"$projectName"}}}])