Find largest document size in MongoDB

Question

Is it possible to find the largest document size in MongoDB?

db.collection.stats() shows average size, which is not really representative because in my

Answer 1

Inspired by Elad Nana's package, but usable in a MongoDB console :

function biggest(collection, limit=100, sort_delta=100) {
  var documents = [];
  cursor = collection.find().readPref("nearest");
  while (cursor.hasNext()) {
    var doc = cursor.next();
    var size = Object.bsonsize(doc);
    if (documents.length < limit || size > documents[limit-1].size) {
      documents.push({ id: doc._id.toString(), size: size });
    }
    if (documents.length > (limit + sort_delta) || !cursor.hasNext()) {
      documents.sort(function (first, second) {
        return second.size - first.size;
      });
      documents = documents.slice(0, limit);
    }
  }
  return documents;
}; biggest(db.collection)

• Uses cursor
• Gives a list of the limit biggest documents, not just the biggest
• Sort & cut output list to limit every sort_delta
• Use nearest as read preference (you might also want to use rs.slaveOk() on the connection to be able to list collections if you're on a slave node)