$hint

  • $hint

Deprecated since v3.2

Starting in v3.2, the $hint operator is deprecated in themongo shell. In the mongo shell,use cursor.hint() instead.

The $hint operator forces the query optimizer to use a specific index tofulfill the query. Specify the index either by the index name or bydocument.

Use $hint for testing query performance and indexingstrategies. The mongo shell provides a helper methodhint() for the $hint operator.

Consider the following operation:

  1. db.users.find().hint( { age: 1 } )

This operation returns all documents in the collection namedusers using the index on the age field.

You can also specify a hint using either of the following forms:

  1. db.users.find()._addSpecial( "$hint", { age : 1 } )
  2. db.users.find( { $query: {}, $hint: { age : 1 } } )

Note

When the query specifies the $hint in the followingform:

  1. db.users.find( { $query: {}, $hint: { age : 1 } } )

Then, in order to include the $explain option, youmust add the $explain option to the document, as inthe following:

  1. db.users.find( { $query: {}, $hint: { age : 1 }, $explain: 1 } )

When an index filter exists for the queryshape, MongoDB ignores the $hint.