[{PartnerName:"Company A",MarketExpertese:[{Sector:{Code:1,TotalYears:1,TotalMonths:20,TotalClients:10}},{Sector:{Code:2,TotalYears:2,TotalMonths:20,TotalClients:10}},{Sector:{Code:3,TotalYears:3,TotalMonths:20,TotalClients:10}}]}]

db.collection.aggregate([{"$unwind":"$MarketExpertese"},{"$project":{PartnerName:1,Taste:{SectorCode:"$MarketExpertese.Sector.Code",TotalYears:"$MarketExpertese.Sector.TotalYears"}}},{"$group":{"_id":"$_id",PartenerName:{"$first":"$PartnerName"},Taste:{"$addToSet":"$Taste"}}}])