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$natural

Definition

$natural

Use the $natural operator to use natural order for the results of a sort operation. Natural order refers to the logical ordering of documents internally within the database.

The $natural operator uses the following syntax to return documents in the order they exist on disk:

db.collection.find().sort( { $natural: 1 } )

Behavior

On a sharded collection the $natural operator returns a collection scan sorted in natural order, the order the database inserts and stores documents on disk.

You cannot specify $natural sort order if the query includes a $text expression.

Examples

Reverse Order

Use -1 to return documents in the reverse order as they occur on disk:

db.collection.find().sort( { $natural: -1 } )

Natural Order Comparison

To demonstrate natural ordering:

  • Create an { normal: 1 } index on a collection (e.g. coll).

  • Insert relevant objects with _id and normal values, for example, a document with _id and normal fields that both hold the same string:

    db.coll.insert( { _id: "01", normal: "01" } )
    
  • Use values with different types for each document, but both fields in the document should have the same value:

  • Use .find().sort().explain() for all operations.

This scenario returns these results when using find() for different _id values; sorting with the $natural operator, _id index, and normal index; and a description of the explain() method output:

    sort()  
find() $natural:1 _id:1 normal:1
_id:ObjectId() explain() used B-Tree cursor explain() used B-Tree cursor explain() used B-Tree cursor
_id:Object() explain() used B-Tree cursor explain() used B-Tree cursor explain() used B-Tree cursor
_id:string() explain() used B-Tree cursor explain() used B-Tree cursor explain() used B-Tree cursor
_id:integer() explain() used B-Tree cursor explain() used B-Tree cursor explain() used B-Tree cursor
_id:BinData() explain() scanned entire collection explain() used B-Tree cursor explain() used B-Tree cursor
normal:(any query) explain() scanned entire collection explain() used B-Tree cursor explain() used B-Tree cursor

Additional Information

cursor.sort()

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