cursor.hint()
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Definition
cursor.hint(index)
Important
mongosh Method
This page documents a
mongosh
method. This is not the documentation for a language-specific driver, such as Node.js.For MongoDB API drivers, refer to the language-specific MongoDB driver documentation.
Call this method on a query to override MongoDB's default index selection and query optimization process. Use
db.collection.getIndexes()
to return the list of current indexes on a collection.The
cursor.hint()
method has the following parameter:ParameterTypeDescriptionindex
string or document
The index to "hint" or force MongoDB to use when performing the query. Specify the index either by the index name or by the index specification document.
You can also specify
{ $natural : 1 }
to force the query to perform a forwards collection scan, or{ $natural : -1 }
for a reverse collection scan.
Compatibility
This method is available in deployments hosted in the following environments:
MongoDB Atlas: The fully managed service for MongoDB deployments in the cloud
Note
This command is supported in all MongoDB Atlas clusters. For information on Atlas support for all commands, see Unsupported Commands.
MongoDB Enterprise: The subscription-based, self-managed version of MongoDB
MongoDB Community: The source-available, free-to-use, and self-managed version of MongoDB
Behavior
When an index filter exists for the query shape, MongoDB ignores the
hint()
.If a query includes a
$text
expression, you cannot usehint()
to specify which index to use for the query.If you use
hint()
on a hidden index or an index that doesn't exist, the operation returns an error.On a time series collections, you can only specify hints using the index name, not the index key pattern.
Examples
Specify an Index
The following example returns all documents in the collection named
users
using the index on the age
field.
db.users.find().hint( { age: 1 } )
You can also specify the index using the index name:
db.users.find().hint( "age_1" )
Force Collection Scans
You can specify { $natural : 1 }
to force the query to perform a forwards
collection scan:
db.users.find().hint( { $natural : 1 } )
You can also specify { $natural : -1 }
to force the query to perform a
reverse collection scan:
db.users.find().hint( { $natural : -1 } )