db.collection.validate()

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Description

Syntax
Behavior
Examples

MongoDB with drivers

This page documents a mongosh method. To see the equivalent method in a MongoDB driver, see the corresponding page for your programming language:

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Description

db.collection.validate(<documents>)

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.

Starting in version 5.0, the db.collection.validate() method can also fix inconsistencies in the collection.

Index inconsistencies include:

An index is multikey but there are no multikey fields.
An index has multikeyPaths covering fields that are not multikey.
An index does not have multikeyPaths but there are multikey documents (for indexes built before 3.4).

If any inconsistencies are detected by the db.collection.validate() command, a warning is returned and the repair flag on the index is set to true.

db.collection.validate() also validates any documents that violate the collection's schema validation rules.

The db.collection.validate() method is a wrapper around the validate command.

Syntax

The db.collection.validate() method has the following syntax:

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

Parameters

The db.collection.validate() method can take the following optional document parameter with the fields:

Field	Type	Description
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	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 these 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 multikey documents are found for an index that is not a multikey index, the index is changed to a multikey index. If multikey documents are found that are not specified by an index's multikey paths, the index's multikey paths are updated. If corrupt documents with invalid BSON data are found, the documents are removed. For more information, see the `--repair` option for `mongod` New in version 5.0.

Behavior

Performance

The 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() 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. Consider only running db.collection.validate() on nodes that are not servicing reads and writes.

To isolate the impact of the validation operation from client applications, run db.collection.validate() on a secondary node.

Convert a secondary node into a replica set hidden member and use the hidden node to further isolate the db.collection.validate() operation.

Tip

Convert the current primary node to a secondary node with rs.stepDown().

Data Throughput Metrics

The $currentOp and the currentOp command include dataThroughputAverage and dataThroughputLastSecond information for validate operations in progress.

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

Examples

To validate a collection myCollection using the default validation setting (specifically, full: false):
```
db.myCollection.validate()
db.myCollection.validate({ })
db.myCollection.validate( { full: false } )
```
To perform a full validation of collection myCollection, specify full: true:
```
db.myCollection.validate( { full: true } )
```
To repair collection myCollection, specify repair: true:
```
db.myCollection.validate( { repair: true } )
```

For details of the output, see Validate Output.

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