validate¶

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Definition
Syntax
Behavior
Examples
Validate Output

Definition¶

validate¶

The validate command checks a collection’s data and indexes for correctness and returns the results.

Starting in version 5.0, the validate command can also find inconsistencies in the collection and fix them if possible.

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.

Note

The validate command does not support views and raises an error when run against a view.

The db.collection.validate() method in mongosh provides a wrapper around validate.

Syntax¶

Changed in version 5.0.

The command has the following syntax:

copy

db.runCommand( {
   validate: <string>,          // Collection name
   full: <boolean>,             // Optional
   repair: <boolean>,           // Optional, added in MongoDB 5.0
   metadata: <boolean>          // Optional, added in MongoDB 5.0.4
} )

mongosh also provides a wrapper db.collection.validate().

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.
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. See also `--repair` option for `mongod` New in version 5.0.
metadata	boolean	Optional. A flag which allows users to perform a quick validation to detect invalid index options without scanning all of the documents and indexes. If `true`, a metadata validation scan is performed. If `false`, no metadata validation scan is not performed. The default is `false`. Running the validate command with `{ metadata: true }` is not supported with any other `validate` options. The `metadata` validation option: Provides you a faster way of identifying invalid indexes by scanning only collections metadata. Provides an alternative to dropping and recreating multiple invalid indexes when used with the collMod command. The `metadata` validation option only scans collection metadata to find invalid indexes more quickly. If there is an invalid index detected, the validate command will prompt you to use the `collMod` command to remove invalid indexes. copy db.runCommand( { collMod: <collectionName> } ) New in version 5.0.4.

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 validation setting (specifically, full: false):
copy
```
db.runCommand( { validate: "myCollection" } )
```
To perform a full validation of collection myCollection, specify full: true:
copy
```
db.runCommand( { validate: "myCollection", full: true } )
```

To repair collection myCollection, specify repair: true:

copy

db.runCommand( { validate: "myCollection", repair: true } )

To validate the metadata in the myCollection collection, specify metadata: true:
copy
```
db.runCommand( { validate: "myCollection", metadata: 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.nNonCompliantDocuments¶: The number of documents not conforming to the collection’s schema.

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

validate.nIndexes¶: The number of indexes on the collection.

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.repaired¶: A boolean that is true if validate repaired the collection.

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 5.0.

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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