Find largest document size in MongoDB?

To find the largest document size in MongoDB, you need to write a script in the shell.

To understand the concept, let us create a collection with the document. The query to create a collection with a document is as follows −

> db.largestDocumentDemo.insertOne({"StudentName":"John"});
{
   "acknowledged" : true,
   "insertedId" : ObjectId("5c8ed2e32f684a30fbdfd57d")
}
> db.largestDocumentDemo.insertOne({"StudentName":"Carol","StudentAge":22,"StudentCountryName":"US","TechnicalSubject":["C","C++","Java","MySQL"]});
{
   "acknowledged" : true,
   "insertedId" : ObjectId("5c8ed3282f684a30fbdfd57e")
}
> db.largestDocumentDemo.insertOne({"StudentName":"Mike","StudentAge":22});
{
   "acknowledged" : true,
   "insertedId" : ObjectId("5c8ed3382f684a30fbdfd57f")
}

Display all documents from a collection with the help of find() method. The query is as follows −

> db.largestDocumentDemo.find().pretty();

The following is the output −

{ "_id" : ObjectId("5c8ed2e32f684a30fbdfd57d"), "StudentName" : "John" }
{
   "_id" : ObjectId("5c8ed3282f684a30fbdfd57e"),
   "StudentName" : "Carol",
   "StudentAge" : 22,
   "StudentCountryName" : "US",
   "TechnicalSubject" : [
      "C",
      "C++",
      "Java",
      "MySQL"
   ]
}
{
   "_id" : ObjectId("5c8ed3382f684a30fbdfd57f"),
   "StudentName" : "Mike",
   "StudentAge" : 22
}

Here is the query to find the largest document size in MongoDB −

> var largestDocumentSize = 0;
> db.largestDocumentDemo.find().forEach(function(myObject) {
   ... var currentDocumentSize = Object.bsonsize(myObject);
   ... if(largestDocumentSize < currentDocumentSize ) {
      ... largestDocumentSize = currentDocumentSize ;
   ... }
... });
> print('The Largest Document Size =' + ' ' +largestDocumentSize);

The following is the output displaying the largest document size −

The Largest Document Size = 160