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

# cursor.readConcern() (mongosh method)

## Definition

**Important: mongosh Method**

This page documents a [`mongosh`](https://www.mongodb.com/docs/mongodb-shell.md#mongodb-binary-bin.mongosh) method. This is *not* the documentation for a language-specific driver, such as Node.js.

For MongoDB API drivers, refer to the language-specific [MongoDB driver documentation.](https://www.mongodb.com/docs/drivers/)

Specify a [read concern](https://www.mongodb.com/docs/manual/reference/glossary.md#std-term-read-concern) for the [`db.collection.find()`](https://www.mongodb.com/docs/manual/reference/method/db.collection.find.md#mongodb-method-db.collection.find) method.

The [`readConcern()`](https://www.mongodb.com/docs/manual/reference/method/cursor.readconcern.md#mongodb-method-cursor.readConcern) method has the following form:

```javascript
db.collection.find().readConcern(<level>)
```

The [`readConcern()`](https://www.mongodb.com/docs/manual/reference/method/cursor.readconcern.md#mongodb-method-cursor.readConcern) method has the following parameter:

| Parameter | Type | Description |
| --- | --- | --- |
| `level` | string | [Read concern](https://www.mongodb.com/docs/manual/reference/glossary.md#std-term-read-concern) level. Possible read concern levels are: [`"local"`](https://www.mongodb.com/docs/manual/reference/read-concern-local.md#mongodb-readconcern-readconcern.-local-). This is the default read concern level for read operations against the primary and secondaries.; [`"available"`](https://www.mongodb.com/docs/manual/reference/read-concern-available.md#mongodb-readconcern-readconcern.-available-). Available for read operations against the primary and secondaries. [`"available"`](https://www.mongodb.com/docs/manual/reference/read-concern-available.md#mongodb-readconcern-readconcern.-available-) behaves the same as [`"local"`](https://www.mongodb.com/docs/manual/reference/read-concern-local.md#mongodb-readconcern-readconcern.-local-) against the primary and non-sharded secondaries. The query returns the instance's most recent data.; [`"majority"`](https://www.mongodb.com/docs/manual/reference/read-concern-majority.md#mongodb-readconcern-readconcern.-majority-). Available for replica sets that use [WiredTiger storage engine.](https://www.mongodb.com/docs/manual/core/wiredtiger.md#std-label-storage-wiredtiger); [`"linearizable"`](https://www.mongodb.com/docs/manual/reference/read-concern-linearizable.md#mongodb-readconcern-readconcern.-linearizable-). Available for read operations on the [`primary`](https://www.mongodb.com/docs/manual/reference/replica-states.md#mongodb-replstate-replstate.PRIMARY) only.; [`"snapshot"`](https://www.mongodb.com/docs/manual/reference/read-concern-snapshot.md#mongodb-readconcern-readconcern.-snapshot-). Available for [multi-document transactions](https://www.mongodb.com/docs/manual/core/transactions.md#std-label-transactions) and certain read operations outside of multi-document transactions. For more formation on the read concern levels, see [Read Concern Levels.](https://www.mongodb.com/docs/manual/reference/read-concern.md#std-label-read-concern-levels) |

## Compatibility

This method is available in deployments hosted in the following environments:

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

**Note:**

This command is supported in all MongoDB Atlas clusters. For information on Atlas support for all commands, see [Unsupported Commands.](https://www.mongodb.com/docs/atlas/unsupported-commands/)

- [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

## Considerations

### Read Your Own Writes

You can use [causally consistent sessions](https://www.mongodb.com/docs/manual/core/read-isolation-consistency-recency.md#std-label-sessions) to read your own writes, if the writes request acknowledgment.

### Linearizable Read Concern Performance

When specifying [`linearizable read concern`](https://www.mongodb.com/docs/manual/reference/read-concern-linearizable.md#mongodb-readconcern-readconcern.-linearizable-), always use [`maxTimeMS()`](https://www.mongodb.com/docs/manual/reference/method/cursor.maxtimems.md#mongodb-method-cursor.maxTimeMS) in case a majority of data bearing members are unavailable.

```javascript
db.restaurants.find( { _id: 5 } ).readConcern("linearizable").maxTimeMS(10000)
```

**See also:**

[Read Concern](https://www.mongodb.com/docs/manual/reference/read-concern.md)