Create index in a MongoDB collection?

MongoDBDatabaseBig Data Analytics

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

> db.demo702.createIndex({"details.id":1});
{
   "createdCollectionAutomatically" : true,
   "numIndexesBefore" : 1,
   "numIndexesAfter" : 2,
   "ok" : 1
}
> db.demo702.insertOne({
...    "details" : [
...       {
...          id:101,
...          studentInfo:{
...             "StudentName" : "Chris",
...             "StudentAge" : 23,
...          }
...       },
...    {
...
...       id: 102,
...       studentInfo:{
...          "StudentName" : "Robert",
...          "StudentAge" : 20,
...       }
...    }
... ]
... }
... );
{
   "acknowledged" : true,
   "insertedId" : ObjectId("5ea6ea3b551299a9f98c93b3")
}

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

> db.demo702.find().pretty();

This will produce the following output −

{
   "_id" : ObjectId("5ea6ea3b551299a9f98c93b3"),
   "details" : [
      {
         "id" : 101,
         "studentInfo" : {
            "StudentName" : "Chris",
            "StudentAge" : 23
         }
      },
      {
         "id" : 102,
         "studentInfo" : {
            "StudentName" : "Robert",
            "StudentAge" : 20
         }
      }
   ]
}
raja
Published on 14-May-2020 13:07:48
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