Indexing large text field to make query faster in MongoDB

To index large text field, use ensureIndex() along with $regex for text search. Let us create a collection with documents −

> db.demo46.ensureIndex({"Name":1});
{
   "createdCollectionAutomatically" : true,
   "numIndexesBefore" : 1,
   "numIndexesAfter" : 2,
   "ok" : 1
}
> db.demo46.insertOne({"Name":"John Smith"});
{
   "acknowledged" : true,
   "insertedId" : ObjectId("5e267004cfb11e5c34d898ed")
}
> db.demo46.insertOne({"Name":"John Doe"});
{
   "acknowledged" : true,
   "insertedId" : ObjectId("5e267009cfb11e5c34d898ee")
}
> db.demo46.insertOne({"Name":"Chris Brown"});
{
   "acknowledged" : true,
   "insertedId" : ObjectId("5e267011cfb11e5c34d898ef")
}

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

> db.demo46.find();

This will produce the following output −

{ "_id" : ObjectId("5e267004cfb11e5c34d898ed"), "Name" : "John Smith" }
{ "_id" : ObjectId("5e267009cfb11e5c34d898ee"), "Name" : "John Doe" }
{ "_id" : ObjectId("5e267011cfb11e5c34d898ef"), "Name" : "Chris Brown" }

Following is the query to index large text field to make query faster −

> db.demo46.find({ Name: { $regex:/^John/}});

This will produce the following output −

{ "_id" : ObjectId("5e267009cfb11e5c34d898ee"), "Name" : "John Doe" }
{ "_id" : ObjectId("5e267004cfb11e5c34d898ed"), "Name" : "John Smith" }