In MongoDB you can remove duplicate documents based on a specific field:

db.yourCollection.aggregate([
     { "$group": {
         "_id": { "yourDuplicateKey": "$yourDuplicateKey" },
         "dups": { "$push": "$_id" },
         "count": { "$sum": 1 }
     }},
     { "$match": { "count": { "$gt": 1 } }}
 ]).forEach(function(doc) {
     doc.dups.shift();
     db.yourCollection.remove({ "_id": {"$in": doc.dups }});
 });

It uses aggregation to group by based on the given key then add its _id into dups field and its count in count field. It will project fields with count of more than 1 using $match. At the end loops over each document and remove all duplicate fields except the first one (`shift` will cause this behaviour).

#mongodb #mongo #duplicates #duplication