> For the complete MongoDB documentation index, see www.mongodb.com/docs/llms.txt

# Specify an Index Name

When you create an index, you can give the index a custom name. Giving your index a name helps distinguish different indexes on your collection. For example, you can more easily identify the indexes used by a query in the query plan's [explain results](https://www.mongodb.com/docs/manual/reference/explain-results.md#std-label-explain-results) if your indexes have distinct names.

To specify the index name, include the `name` option when you create the index:

```javascript
db.<collection>.createIndex(
   { <field>: <value> },
   { name: "<indexName>" }
)
```

## About this Task

Before you specify an index name, consider the following:

- Index names must be unique. Creating an index with the name of an existing index returns an error.

- You can't rename an existing index. Instead, you must [drop](https://www.mongodb.com/docs/manual/core/indexes/drop-index.md#std-label-drop-an-index) and recreate the index with a new name.

### Default Index Names

If you don't specify a name during index creation, the system generates the name by concatenating each index key field and value with underscores. For example:

| Index | Default Name |
| --- | --- |
| `{ score : 1 }` | `score_1` |
| `{ content : "text", "description.tags": "text" }` | `content_text_description.tags_text` |
| `{ category : 1, locale : "2dsphere"}` | `category_1_locale_2dsphere` |
| `{ "fieldA" : 1, "fieldB" : "hashed", "fieldC" : -1 }` | `fieldA_1_fieldB_hashed_fieldC_-1` |

## Procedure

The examples on this page use data from the [sample\_mflix dataset](https://www.mongodb.com/docs/manual/sample-data/sample-mflix.md#std-label-sample-mflix). For details on how to load this dataset into your self-managed MongoDB deployment, see [Load the Sample Dataset](https://www.mongodb.com/docs/manual/sample-data/load-sample-data-local.md#std-label-sample-dataset-local). If you made any modifications to the sample databases, you may need to drop and recreate the databases to run the examples on this page.

Create a text index on the `name` and `text` fields. Set the index `name` to `CommentsTextIndex`:

```javascript
db.comments.createIndex(
   {
     name: "text",
     text: "text"
   },
   {
     name: "CommentsTextIndex"
   }
)

```

**Output:**

```javascript
CommentsTextIndex

```

## Results

After you create the index, you can use the [`db.collection.getIndexes()`](https://www.mongodb.com/docs/manual/reference/method/db.collection.getindexes.md#mongodb-method-db.collection.getIndexes) method to get the index name:

```javascript
db.comments.getIndexes()

```

**Output:**

```javascript
[
  {
    v: 2,
    key: {
      _id: 1
    },
    name: '_id_'
  },
  {
    v: 2,
    key: {
      _fts: 'text',
      _ftsx: 1
    },
    name: 'CommentsTextIndex',
    weights: {
      name: 1,
      text: 1
    },
    default_language: 'english',
    language_override: 'language',
    textIndexVersion: 3
  }
]

```

## Learn More

- To learn how to create an index, see [Create an Index.](https://www.mongodb.com/docs/manual/core/indexes/create-index.md#std-label-manual-create-an-index)

- For more information about index properties, see [Index Properties.](https://www.mongodb.com/docs/manual/core/indexes/index-properties.md#std-label-index-properties)