Deduplicate users

deduplicate-users.js

db.user.aggregate([
  { $sort: { created_at: 1 } },
  {
    "$group": {
      _id: "$email",
      dups: { $addToSet: "$_id" } ,
      count: { $sum : 1 }
    }
  },
  {
    "$match": {
      count: { "$gt": 1 }
    }
  }
]).forEach(function(doc) {
  doc.dups.shift();
  var res = db.user.remove({
    _id: {$in: doc.dups}
  });
  print(`Removed ${res.deletedCount} duplicate for ${doc._id}`)
})