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

# db.collection.validate() (mongosh method)

## Description

**Changed in version 6.2**

Validates a collection. The method scans a collection data and indexes for correctness and returns the result. For details of the output, see [Validate Output.](https://www.mongodb.com/docs/manual/reference/command/validate.md#std-label-validate-output)

Starting in version 5.0, the [`db.collection.validate()`](https://www.mongodb.com/docs/manual/reference/method/db.collection.validate.md#mongodb-method-db.collection.validate) method can also fix inconsistencies in the collection.

Index inconsistencies include:

- An index is [multikey](https://www.mongodb.com/docs/manual/core/indexes/index-types/index-multikey.md#std-label-index-type-multikey) but there are no multikey fields.

- An index has [multikeyPaths](https://www.mongodb.com/docs/manual/core/indexes/index-types/index-multikey.md#std-label-compound_multikey_indexes) covering fields that are not multikey.

- An index does not have [multikeyPaths](https://www.mongodb.com/docs/manual/core/indexes/index-types/index-multikey.md#std-label-compound_multikey_indexes) but there are multikey documents (for indexes built before 3.4).

If any inconsistencies are detected by the [`db.collection.validate()`](https://www.mongodb.com/docs/manual/reference/method/db.collection.validate.md#mongodb-method-db.collection.validate) command, a warning is returned and the repair flag on the index is set to `true`.

[`db.collection.validate()`](https://www.mongodb.com/docs/manual/reference/method/db.collection.validate.md#mongodb-method-db.collection.validate) also validates any documents that violate the collection's [schema validation rules.](https://www.mongodb.com/docs/manual/core/schema-validation.md#std-label-schema-validation-document)

The [`db.collection.validate()`](https://www.mongodb.com/docs/manual/reference/method/db.collection.validate.md#mongodb-method-db.collection.validate) method is a wrapper around the [`validate`](https://www.mongodb.com/docs/manual/reference/command/validate.md#mongodb-dbcommand-dbcmd.validate) command.

## 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

## Syntax

The [`db.collection.validate()`](https://www.mongodb.com/docs/manual/reference/method/db.collection.validate.md#mongodb-method-db.collection.validate) method has the following syntax:

```javascript
db.collection.validate( {
   full: <boolean>,  // Optional
   repair: <boolean>,  // Optional, added in MongoDB 5.0
   checkBSONConformance: <boolean>  // Optional, added in MongoDB 6.2
} )
```

### Parameters

The [`db.collection.validate()`](https://www.mongodb.com/docs/manual/reference/method/db.collection.validate.md#mongodb-method-db.collection.validate) method can take the following optional document parameter with the fields:

| Field | Type | Description |
| --- | --- | --- |
| [full](https://www.mongodb.com/docs/manual/reference/method/db.collection.validate.md#std-label-method-validate-full) | boolean | *Optional*. A flag that determines whether the command performs a slower but more thorough check or a faster but less thorough check. If `true`, performs a more thorough check with the following exception:Full validation on the `oplog` for WiredTiger skips the more thorough check.; If `false`, omits some checks for a faster but less thorough check. The default is `false`. For the WiredTiger storage engine, only the `full` validation process will force a checkpoint and flush all in-memory data to disk before verifying the on-disk data. |
| [repair](https://www.mongodb.com/docs/manual/reference/method/db.collection.validate.md#std-label-method-validate-repair) | boolean | *Optional*. A flag that determines whether the command performs a repair. If `true`, a repair is performed.; If `false`, no repair is performed. The default is `false`. A repair can only be run on a standalone node. The repair fixes the following issues: If missing index entries are found, the missing keys are inserted into the index.; If extra index entries are found, the extra keys are removed from the index.; If corrupt documents with invalid BSON data are found, the documents are removed. IMPORTANT: To set `repair` to `true`, you must set the `fixMultikey` option to `true`. For more information, see the [`--repair`](https://www.mongodb.com/docs/manual/reference/program/mongod.md#std-option-mongod.--repair) option for [`mongod`](https://www.mongodb.com/docs/manual/reference/program/mongod.md#mongodb-binary-bin.mongod) **New in version 5.0** |
| `fixMultikey` | boolean | *Optional*. If `true`, MongoDB fixes the following issues: If the `validate` command finds [multikey](https://www.mongodb.com/docs/manual/core/indexes/index-types/index-multikey.md#std-label-index-type-multikey) documents for a non-multikey index, MongoDB changes the index to a multikey index.; If the `validate` command finds [multikey](https://www.mongodb.com/docs/manual/core/indexes/index-types/index-multikey.md#std-label-index-type-multikey) documents that aren't specified by an index's multikey paths, MongoDB updates index's multikey paths. The default is `false`. **New in version 8.1** |
| [checkBSONConformance](https://www.mongodb.com/docs/manual/reference/method/db.collection.validate.md#std-label-method-validate-checkBSONConformance) | boolean | *Optional*. If `true`, the collection is checked to ensure the [BSON documents](https://www.mongodb.com/docs/manual/core/document.md#std-label-bson-document-format) conform to the BSON specifications. The checks increase the time to complete the validation operation. Any issues are returned as a warning. `checkBSONConformance`: Default is `false`.; Cannot be used with:`repair` set to `true`.; `metadata` set to `true`. **New in version 6.2** |

## Behavior

### Performance

The [`db.collection.validate()`](https://www.mongodb.com/docs/manual/reference/method/db.collection.validate.md#mongodb-method-db.collection.validate) method is potentially resource intensive and may impact the performance of your MongoDB instance, particularly on larger data sets.

The [`db.collection.validate()`](https://www.mongodb.com/docs/manual/reference/method/db.collection.validate.md#mongodb-method-db.collection.validate) method obtains an exclusive lock on the collection. This will block all reads and writes on the collection until the operation finishes. When run on a secondary, the operation can block all other operations on that secondary until it finishes.

**Warning:**

Validation has exclusive lock requirements that affect performance on primaries and on secondaries that are servicing reads. Consider only running [`db.collection.validate()`](https://www.mongodb.com/docs/manual/reference/method/db.collection.validate.md#mongodb-method-db.collection.validate) on nodes that are not servicing reads or writes.

To minimize impact on the primary, the majority of the data-bearing (non-arbiter), voting members in the cluster must be available and must not have significant replication lag.

To minimize the impact of the validation operation on client applications, run [`db.collection.validate()`](https://www.mongodb.com/docs/manual/reference/method/db.collection.validate.md#mongodb-method-db.collection.validate) on a secondary node that is not servicing read requests. You can convert the current primary node to a secondary node, by running the [`rs.stepDown()`](https://www.mongodb.com/docs/manual/reference/method/rs.stepdown.md#mongodb-method-rs.stepDown) method.

To completely isolate the [`db.collection.validate()`](https://www.mongodb.com/docs/manual/reference/method/db.collection.validate.md#mongodb-method-db.collection.validate) operation from client traffic, choose one of the following options:

- Isolate a replica set member by following the [rolling maintenance procedure](https://www.mongodb.com/docs/manual/tutorial/perform-maintenance-on-replica-set-members.md#std-label-perform-maint-on-replica-set) to temporarily remove it from the cluster.

- [Convert a secondary node](https://www.mongodb.com/docs/manual/tutorial/configure-a-hidden-replica-set-member.md#std-label-configure-hidden-replica-set-member) to a replica set [hidden member](https://www.mongodb.com/docs/manual/core/replica-set-hidden-member.md#std-label-replica-set-hidden-members) and perform the validation on the hidden node.

### Data Throughput Metrics

The [`$currentOp`](https://www.mongodb.com/docs/manual/reference/operator/aggregation/currentop.md#mongodb-pipeline-pipe.-currentOp) and the [`currentOp`](https://www.mongodb.com/docs/manual/reference/command/currentop.md#mongodb-dbcommand-dbcmd.currentOp) command include [`dataThroughputAverage`](https://www.mongodb.com/docs/manual/reference/operator/aggregation/currentop.md#mongodb-data--currentOp.dataThroughputAverage) and [`dataThroughputLastSecond`](https://www.mongodb.com/docs/manual/reference/operator/aggregation/currentop.md#mongodb-data--currentOp.dataThroughputLastSecond) information for validate operations in progress.

The log messages for validate operations include `dataThroughputAverage` and `dataThroughputLastSecond` information.

### Collection Validation Improvements

Starting in MongoDB 6.2, the [`validate`](https://www.mongodb.com/docs/manual/reference/command/validate.md#mongodb-dbcommand-dbcmd.validate) command and [`db.collection.validate()`](https://www.mongodb.com/docs/manual/reference/method/db.collection.validate.md#mongodb-method-db.collection.validate) method:

- Check collections to ensure the [BSON documents](https://www.mongodb.com/docs/manual/core/document.md#std-label-bson-document-format) conform to the BSON specifications.

- Check [time series collections](https://www.mongodb.com/docs/manual/core/timeseries-collections.md#std-label-manual-timeseries-collection) for internal data inconsistencies.

- Have a new option `checkBSONConformance` that enables comprehensive BSON checks.

Starting in MongoDB 8.3, the `validate` command and `db.collection.validate()` method check collections to ensure a collection doesn't have any documents that exceed 16 MB.

## Examples

- To validate a collection `myCollection` using the default validation setting (specifically, [full: false](https://www.mongodb.com/docs/manual/reference/method/db.collection.validate.md#std-label-method-validate-full)):

  ```javascript
  db.myCollection.validate()

  db.myCollection.validate({ })

  db.myCollection.validate( { full: false } )
  ```

- To perform a full validation of collection `myCollection`, specify [full: true:](https://www.mongodb.com/docs/manual/reference/method/db.collection.validate.md#std-label-method-validate-full)

  ```javascript
  db.myCollection.validate( { full: true } )
  ```

- To repair collection `myCollection`, specify [repair: true:](https://www.mongodb.com/docs/manual/reference/method/db.collection.validate.md#std-label-method-validate-repair)

  ```javascript
  db.myCollection.validate( { repair: true } )
  ```

- To perform additional BSON conformance checks in `myCollection`, specify [checkBSONConformance: true:](https://www.mongodb.com/docs/manual/reference/method/db.collection.validate.md#std-label-method-validate-checkBSONConformance)

  ```javascript
  db.myCollection.validate( { checkBSONConformance: true } )
  ```

For details of the output, see [Validate Output.](https://www.mongodb.com/docs/manual/reference/command/validate.md#std-label-validate-output)