Find duplicate records in MongoDB

Question

How would I find duplicate fields in a mongo collection.

I\'d like to check if any of the \"name\" fields are duplicates.

{
    \"name\" : \"ksqn291\         


        

Answer 1

db.getCollection('orders').aggregate([  
    {$group: { 
            _id: {name: "$name"},
            uniqueIds: {$addToSet: "$_id"},
            count: {$sum: 1}
        } 
    },
    {$match: { 
        count: {"$gt": 1}
        }
    }
])

First Group Query the group according to the fields.

Then we check the unique Id and count it, If count is greater then 1 then the field is duplicate in the entire collection so that thing is to be handle by $match query.