I am getting the [Error: [firestore/failed-precondition] The query requires an index. when i am adding the orderBy(‘createdAt’).

I am getting the following error when i am adding the orderBy(‘crearedAt’) on the firestore collection.

**[Error: [firestore/failed-precondition] The query requires an index.
**

my collection is

export const CommentsCollection = firestore().collection('comments');

When i am adding the orderBy(‘createdAt’) like

let commentsQuery = CommentsCollection.orderBy('createdAt').where( 'postId', '==', data.postId, );

I have already created the index on the firebase console.