How to force MongoDB to use the BasicCursor instead of an index?

To avoid using index, use hint() in MongoDB. Let us create a collection with documents −

> db.demo31.createIndex({"StudentFirstName":1});
{
   "createdCollectionAutomatically" : true,
   "numIndexesBefore" : 1,
   "numIndexesAfter" : 2,
   "ok" : 1
}
> db.demo31.insertOne({"StudentFirstName":"John"});
{
   "acknowledged" : true,
   "insertedId" : ObjectId("5e174f8fcfb11e5c34d898c1")
}
> db.demo31.insertOne({"StudentFirstName":"Jace"});
{
   "acknowledged" : true,
   "insertedId" : ObjectId("5e174f97cfb11e5c34d898c2")
}
> db.demo31.insertOne({"StudentFirstName":"Chris"});
{
   "acknowledged" : true,
   "insertedId" : ObjectId("5e174f9ccfb11e5c34d898c3")
}
> db.demo31.insertOne({"StudentFirstName":"James"});
{
   "acknowledged" : true,
   "insertedId" : ObjectId("5e174fa0cfb11e5c34d898c4")
}

Display all documents from a collection with the help of find() method −

> db.demo31.find();

This will produce the following output −

{ "_id" : ObjectId("5e174f8fcfb11e5c34d898c1"), "StudentFirstName" : "John" }
{ "_id" : ObjectId("5e174f97cfb11e5c34d898c2"), "StudentFirstName" : "Jace" }
{ "_id" : ObjectId("5e174f9ccfb11e5c34d898c3"), "StudentFirstName" : "Chris" }
{ "_id" : ObjectId("5e174fa0cfb11e5c34d898c4"), "StudentFirstName" : "James" }

Following is the query to force MongoDB to use BasicCursor instead of an index −

> db.demo31.find({"StudentFirstName": {$regex: '^Ja'}}).hint({ $natural: 1});

This will produce the following output −

{ "_id" : ObjectId("5e174f97cfb11e5c34d898c2"), "StudentFirstName" : "Jace" }
{ "_id" : ObjectId("5e174fa0cfb11e5c34d898c4"), "StudentFirstName" : "James" }