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

# $exists (query predicate operator)

## Definition

The [`$exists`](https://www.mongodb.com/docs/manual/reference/operator/query/exists.md#mongodb-query-op.-exists) operator matches documents that contain or do not contain a specified field, including documents where the field value is `null`.

**Note:**

MongoDB `$exists` does **not** correspond to SQL operator `exists`. For SQL `exists`, see [`$in`.](https://www.mongodb.com/docs/manual/reference/operator/query/in.md#mongodb-query-op.-in)

For MongoDB Search `exists`, see [exists (MongoDB Search Operator)](https://www.mongodb.com/docs/search/query/operators-collectors/exists.md#std-label-exists-ref) in the Atlas documentation.

## Compatibility

You can use `$exists` for deployments hosted in the following environments:

- [MongoDB Atlas](https://www.mongodb.com/docs/atlas): The fully managed service for MongoDB deployments in the cloud

* [MongoDB Enterprise](https://www.mongodb.com/docs/manual/administration/install-enterprise.md#std-label-install-mdb-enterprise): The subscription-based, self-managed version of MongoDB

* [MongoDB Community](https://www.mongodb.com/docs/manual/administration/install-community.md#std-label-install-mdb-community-edition): The source-available, free-to-use, and self-managed version of MongoDB

**Note:**

[Expressions](https://www.mongodb.com/docs/manual/reference/mql/expressions.md#std-label-aggregation-expressions) do not support the [`$exists`](https://www.mongodb.com/docs/manual/reference/operator/query/exists.md#mongodb-query-op.-exists) operator. To check for the existence of a field in an expression, you can use the [`$type`](https://www.mongodb.com/docs/manual/reference/operator/aggregation/type.md#mongodb-expression-exp.-type) aggregation operator to check if a field has a type of `missing`.

For more information, see [$type Existence Check.](https://www.mongodb.com/docs/manual/reference/operator/aggregation/type.md#std-label-missing-type-existence-check)

## Syntax

To specify an [`$exists`](https://www.mongodb.com/docs/manual/reference/operator/query/exists.md#mongodb-query-op.-exists) expression, use the following prototype:

```javascript
{ field: { $exists: <boolean> } }
```

When `<boolean>` is true, [`$exists`](https://www.mongodb.com/docs/manual/reference/operator/query/exists.md#mongodb-query-op.-exists) matches the documents that contain the field, including documents where the field value is `null`. If `<boolean>` is false, the query returns only the documents that do not contain the field.

## Query Data on Atlas by Using MongoDB Search

For data stored in [MongoDB Atlas](https://www.mongodb.com/docs/atlas/), you can use the [MongoDB Search](https://www.mongodb.com/docs/atlas/atlas-search/) [in Operator](https://www.mongodb.com/docs/search/query/operators-collectors/in.md#std-label-in-ref) operator when running [`$search`](https://www.mongodb.com/docs/search/query/aggregation-stages/search.md#mongodb-pipeline-pipe.-search) queries. Running [`$exists`](https://www.mongodb.com/docs/manual/reference/operator/query/exists.md#mongodb-query-op.-exists) after [`$search`](https://www.mongodb.com/docs/search/query/aggregation-stages/search.md#mongodb-pipeline-pipe.-search) is less performant than running [`$search`](https://www.mongodb.com/docs/search/query/aggregation-stages/search.md#mongodb-pipeline-pipe.-search) with the [in Operator](https://www.mongodb.com/docs/search/query/operators-collectors/in.md#std-label-in-ref) operator.

To learn more about the MongoDB Search version of this operator, see the [in Operator](https://www.mongodb.com/docs/search/query/operators-collectors/in.md#std-label-in-ref) operator in the Atlas documentation.

## Examples

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.

### Exists and Not Equal To

Consider the following example:

```javascript
db.movies.find( { rated: { $exists: true, $nin: [ "R", "PG-13" ] } } ).limit(5)

```

This query selects 5 documents in the `movies` collection where the `rated` field exists *and* its value does not equal `"R"` or `"PG-13"`.

### Null Values

The `movies` collection in the `sample_mflix` database contains documents where some fields are present and others are missing. For example, the `rated` field exists in 11,455 documents and is absent from the remaining 9,894 documents.

#### `$exists: true`

The following query specifies the query predicate `rated: { $exists: true }`:

```javascript
db.movies.find( { rated: { $exists: true } }, { _id: 0, title: 1, rated: 1 } ).limit( 3 )

```

The results consist of three documents that contain the field `rated`:

```javascript
[
  { title: 'The Great Train Robbery', rated: 'TV-G' },
  { title: 'A Corner in Wheat', rated: 'G' },
  { title: 'Traffic in Souls', rated: 'TV-PG' }
]
```

#### `$exists: false`

The following query specifies the query predicate `rated: { $exists: false }`:

```javascript
db.movies.find( { rated: { $exists: false } }, { _id: 0, title: 1, year: 1 } ).limit( 3 )

```

The results consist of three documents that do not contain the field `rated`:

```javascript
[
  {
    title: 'Winsor McCay, the Famous Cartoonist of the N.Y. Herald and His Moving Comics',
    year: 1911
  },
  { title: 'Gertie the Dinosaur', year: 1914 },
  { title: 'In the Land of the Head Hunters', year: 1914 }
]
```

### Use a Sparse Index to Improve `$exists` Performance

The following table compares `$exists` query performance using sparse and non-sparse indexes:

| `$exists` Query | Using a Sparse Index | Using a Non-Sparse Index |
| --- | --- | --- |
| `{ $exists: true }` | Most efficient. MongoDB can make an exact match and does not require a `FETCH`. | More efficient than queries without an index, but still requires a `FETCH`. |
| `{ $exists: false }` | Cannot use the index and requires a `COLLSCAN`. | Requires a `FETCH`. |

Queries that use `{ $exists: true }` on fields that use a non-sparse index or that use `{ $exists: true }` on fields that are not indexed examine all documents in a collection. To improve performance, create a [sparse index](https://www.mongodb.com/docs/manual/core/index-sparse.md#std-label-index-type-sparse) on the `field` as shown in the following scenario:

1. The `movies` collection contains documents where the `metacritic` field is present in some documents and absent from others. Of the 21,349 documents, 6,964 have the `metacritic` field and 14,385 do not.

2. Create a [sparse index](https://www.mongodb.com/docs/manual/core/index-sparse.md#std-label-index-type-sparse) on the `metacritic` field:

   ```javascript
   db.movies.createIndex(
      { metacritic: 1 },
      { name: "metacriticSparseIndex", sparse: true }
   )

   ```

3. The following example counts the documents where the `metacritic` field has a value (including null) and uses the [sparse index:](https://www.mongodb.com/docs/manual/core/index-sparse.md#std-label-index-type-sparse)

   ```javascript
   db.movies.countDocuments( { metacritic: { $exists: true } } )

   ```

   The example returns 6964. The operation does not count the documents that are missing the `metacritic` field.

**Tip:**

If you only need documents where the `field` has a non-null value, you:

- Can use `$ne: null` instead of `$exists: true`.

- Do not need a [sparse index](https://www.mongodb.com/docs/manual/core/index-sparse.md#std-label-index-type-sparse) on the `field`.

For example, using the `movies` collection:

```javascript
db.movies.countDocuments( { metacritic: { $ne: null } } )

```

The example returns 6964. Documents that are missing the `metacritic` value or have a null `metacritic` value are not counted.

## Learn More

- [Query for Null or Missing Fields](https://www.mongodb.com/docs/manual/tutorial/query-for-null-fields.md#std-label-faq-developers-query-for-nulls)

- [`$nin`](https://www.mongodb.com/docs/manual/reference/operator/query/nin.md#mongodb-query-op.-nin)

- [`$in`](https://www.mongodb.com/docs/manual/reference/operator/query/in.md#mongodb-query-op.-in)