[{name:"xxx",labels:[{category:"Language",values:["English","Spanish"],},{category:"Hobby",values:["Read","Cook","Read"],},]},{name:"yyy",labels:[{category:"Language",values:["English","English"],},{category:"Hobby",values:["Read","Play","Play"],},]},]

db.collection.update({},[{"$set":{labels:{$map:{input:"$labels",in:{$mergeObjects:["$$this",{values:{$setUnion:"$$this.values"}}]}}}}},],{"multi":true,"upsert":false})