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validate

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Definition

validate: The validate command checks a collection's data and indexes for correctness and returns the results.
Tip
In the mongo Shell, this command can also be run through the validate() helper method.
Helper methods are convenient for mongo users, but they may not return the same level of information as database commands. In cases where the convenience is not needed or the additional return fields are required, use the database command.
Note
The validate command does not support views and raises an error when run against a view.

Syntax

The command has the following syntax:

db.runCommand( {
   validate: <string>,          // Collection name
   full: <boolean>              // Optional.
} )

Command Fields

The command takes the following fields:

Field	Type	Description
`validate`	string	The name of the collection to 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: Starting in MongoDB 4.4, full validation on the `oplog` for WiredTiger skips the more thorough check. The `validate.warnings` includes a notice of the behavior. If `false`, omits some checks for a faster but less thorough check. The default is `false`. Starting in MongoDB 3.6, 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. In previous versions, the data validation process for the WT storage engine always forces a checkpoint.

Behavior

Performance

The validate command can be slow, particularly on larger data sets.

The validate command obtains an exclusive lock W on the collection. This will block all reads and writes on the collection until the operation finishes. When run on a secondary, the validate operation can block all other operations on that secondary until it finishes.

Warning

Due to the performance impact of validation, consider running validate only on secondary replica set nodes. You can use rs.stepDown() to instruct the current primary node to become a secondary to avoid impacting a live primary node.

Data Throughput Metrics

Starting in version MongoDB 4.4,

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.

Restrictions

MongoDB drivers automatically set afterClusterTime for operations associated with causally consistent sessions. Starting in MongoDB 4.2, the validate command no longer supports afterClusterTime. As such, validate cannot be associated with causally consistent sessions.

Examples

To validate a collection myCollection using the default settings (i.e. full: false)
```
db.runCommand( { validate: "myCollection" } )
```
To perform a full validation of collection myCollection
```
db.runCommand( { validate: "myCollection", full: true } )
```

Validate Output

Note

The output may vary depending on the version and specific configuration of your MongoDB instance.

Specify full: true for more detailed output.

validate.nInvalidDocuments: The number of invalid documents in the collection.

validate.nrecords: The number of documents in the collection.

validate.nIndexes: The number of indexes on the collection that were validated.

validate.keysPerIndex

A document that contains the name and index entry count for each index on the collection.

"keysPerIndex" : {
   "_id_" : <num>,
   "<index2_name>" : <num>,
   ...
}

Starting in MongoDB 4.2 (and 4.0.10+ and 3.6.13+), keysPerIndex identifies the index by its name only. Earlier versions of MongoDB displayed the full namespace of the index; i.e. <db>.<collection>.$<index_name>

validate.indexDetails

A document that contains the status of the index validation for each index.

"indexDetails" : {
   "_id_" : {
      "valid" : <boolean>
   },
   "<index2_name>" : {
      "valid" : <boolean>
   },
   ...
}

Starting in MongoDB 4.2 (and 4.0.10+ and 3.6.13+),

indexDetails identifies the specific index (or indexes) that is invalid. Earlier versions of MongoDB would mark all indexes as invalid, if any of the indexes were invalid.
indexDetails identifies the index by its name only. Earlier versions of MongoDB displayed the full namespace of the index; i.e. <db>.<collection>.$<index_name>.

validate.ns: The full namespace name of the collection. Namespaces include the database name and the collection name in the form database.collection.

validate.valid: A boolean that is true if validate determines that all aspects of the collection are valid. When false, see the errors field for more information.

validate.warnings

An array that contains warning messages, if any, regarding the validate operation itself. The warning messages do not indicate that the collection is itself invalid. For example:

"warnings" : [
   "Could not complete validation of table:collection-28-6471619540207520785. This is a transient issue as the collection was actively in use by other operations."
],

validate.errors: If the collection is not valid (i.e valid is false), this field will contain a message describing the validation error.

validate.extraIndexEntries

An array that contains information for each index entry that points to a document that does not exist in the collection.

"extraIndexEntries" : [
   {
      "indexName" : <string>,
      "recordId" : <NumberLong>,  // for the non-existent document
      "indexKey" : {
         "<key1>" : <value>,
         ...
      }
   }
   ...
]

Note

For the extraIndexEntries array, the sum of all the indexKey field sizes has a limit of 1MB where the sizes include both the keys and values for the indexKey. If the sum exceeds this size, the warning field displays a message.

Available starting in MongoDB 4.2 (and 4.0.10+ and 3.6.13+)

validate.missingIndexEntries

An array that contains information for each document that is missing the corresponding index entry.

"missingIndexEntries" : [
   {
      "indexName" : <string>,
      "recordId" : <NumberLong>,
      "idKey" : <_id key value>,     // The _id value of the document. Only present if an ``_id`` index exists.
      "indexKey" : {                 // The missing index entry
         "<key1>" : <value>,
         ...
      }
   }
   ...
 ]

Note

For the missingIndexEntries array, the sum of the idKey field size and all its indexKey field sizes has a limit of 1MB where the field sizes include both the keys and values for the idKey and indexKey. If the sum exceeds this size, the warning field displays a message.

Available starting in MongoDB 4.2 (and 4.0.10+ and 3.6.13+)

validate.corruptRecords

An array of RecordId values for documents that are unreadable, possibly because the data is damaged. These documents are reported as corrupt during validation. A RecordId is a 64-bit integer internal key that uniquely identifies a document in a collection.

"corruptRecords" : [
   NumberLong(1),  // RecordId 1
   NumberLong(2)   // RecordId 2
]

New in version 4.4.7.

validate.ok: An integer with the value 1 when the command succeeds. If the command fails the ok field has a value of 0.

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Definition

Tip

Note

Syntax

Command Fields

Behavior

Performance

Warning

Data Throughput Metrics

Restrictions

Examples

Validate Output

Note

Note

Note