db.createCollection()

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Definition

Compatibility
Syntax
Access Control
Behavior
Examples

Definition

db.createCollection(name, options)

Creates a new collection or view. For views, see also db.createView().

Because MongoDB creates a collection implicitly when the collection is first referenced in a command, this method is used primarily for creating new collections that use specific options. For example, you use db.createCollection() to create a capped collection, or to create a new collection that uses document validation.

db.createCollection() is a wrapper around the database command create.

Compatibility

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

MongoDB 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.

MongoDB Enterprise: The subscription-based, self-managed version of MongoDB
MongoDB Community: The source-available, free-to-use, and self-managed version of MongoDB

Syntax

The db.createCollection() method has the following prototype form:

db.createCollection( <name>,
    {
      capped: <boolean>,
      timeseries: {                  // Added in MongoDB 5.0
         timeField: <string>,        // required for time series collections
         metaField: <string>,
         granularity: <string>
      },
      expireAfterSeconds: <number>,
      clusteredIndex: <document>,  // Added in MongoDB 5.3
      changeStreamPreAndPostImages: <document>,  // Added in MongoDB 6.0
      size: <number>,
      max: <number>,
      storageEngine: <document>,
      validator: <document>,
      validationLevel: <string>,
      validationAction: <string>,
      indexOptionDefaults: <document>,
      viewOn: <string>,
      pipeline: <pipeline>,
      collation: <document>,
      writeConcern: <document>
    }
  )

The db.createCollection() method has the following parameters:

Parameter	Type	Description
`name`	string	The name of the collection to create. See Naming Restrictions.
`options`	document	Optional. Configuration options for creating a: Capped collection Clustered collection View

The options document contains the following fields:

Field

Type

Description

capped

boolean

Optional. To create a capped collection, specify true. If you specify true, you must also set a maximum size in the size field.

timeseries.timeField

string

Required when creating a time series collection. The name of the field which contains the date in each time series document. Documents in a time series collection must have a valid BSON date as the value for the timeField.

timeseries.metaField

string

Optional. The name of the field which contains metadata in each time series document. The metadata in the specified field should be data that is used to label a unique series of documents. The metadata should rarely, if ever, change.

The name of the specified field may not be _id or the same as the timeseries.timeField. The field can be of any type except array.

timeseries.granularity

string

Optional, do not use if setting bucketRoundingSeconds and bucketMaxSpanSeconds. Possible values are seconds (default), minutes, and hours.

Set granularity to the value that most closely matches the time between consecutive incoming timestamps. This improves performance by optimizing how MongoDB internally stores data in the collection.

For more information on granularity and bucket intervals, see Set Granularity for Time Series Data.

expireAfterSeconds

number

Optional. Specifies the seconds after which documents in a time series collection expire. MongoDB deletes expired documents automatically.

size

number

Optional. Specify a maximum size in bytes for a capped collection. Once a capped collection reaches its maximum size, MongoDB removes the older documents to make space for the new documents. The size field is required for capped collections and ignored for other collections.

max

number

Optional. The maximum number of documents allowed in the capped collection. The size limit takes precedence over this limit. If a capped collection reaches the size limit before it reaches the maximum number of documents, MongoDB removes old documents. If you prefer to use the max limit, ensure that the size limit, which is required for a capped collection, is sufficient to contain the maximum number of documents.

storageEngine

document

Optional. Available for the WiredTiger storage engine only.

Allows users to specify configuration to the storage engine on a per-collection basis when creating a collection. The value of the storageEngine option should take the following form:

{ <storage-engine-name>: <options> }

Storage engine configuration specified when creating collections are validated and logged to the oplog during replication to support replica sets with members that use different storage engines.

For details, see Specify Storage Engine Options.

validator

document

Optional. Allows users to specify validation rules or expressions for the collection.

The validator option takes a document that specifies the validation rules or expressions. You can specify the expressions using the same operators as the query operators with the exception of $near, $nearSphere, $text, and $where.

To learn how to create a collection with schema validation, see JSON Schema.

validationLevel

string

Optional. Determines how strictly MongoDB applies the validation rules to existing documents during an update.

"off": No validation for inserts or updates.
"strict": Default Apply validation rules to all inserts and all updates.
"moderate": Apply validation rules to inserts and to updates on existing valid documents. Do not apply rules to updates on existing invalid documents.

validationAction

string

Optional. Determines whether to error on invalid documents or just warn about the violations but allow invalid documents to be inserted.

IMPORTANT: Validation of documents only applies to those documents as determined by the validationLevel.

indexOptionDefaults

document

Optional. Allows users to specify a default configuration for indexes when creating a collection.

The indexOptionDefaults option accepts a storageEngine document, which should take the following form:

{ <storage-engine-name>: <options> }

Storage engine configuration specified when creating indexes are validated and logged to the oplog during replication to support replica sets with members that use different storage engines.

viewOn

string

The name of the source collection or view from which to create a view. For details, see db.createView().

pipeline

array

An array that consists of the aggregation pipeline stage(s). db.createView() creates a view by applying the specified pipeline to the viewOn collection or view. For details, see db.createView().

collation

document

Specifies the default collation for the collection.

Collation allows users to specify language-specific rules for string comparison, such as rules for lettercase and accent marks.

The collation option has the following syntax:

collation: {
   locale: <string>,
   caseLevel: <boolean>,
   caseFirst: <string>,
   strength: <int>,
   numericOrdering: <boolean>,
   alternate: <string>,
   maxVariable: <string>,
   backwards: <boolean>
}

When specifying collation, the locale field is mandatory; all other collation fields are optional. For descriptions of the fields, see Collation Document.

If you specify a collation at the collection level:

Indexes on that collection will be created with that collation unless the index creation operation explicitly specify a different collation.
Operations on that collection use the collection's default collation unless they explicitly specify a different collation.
You cannot specify multiple collations for an operation. For example, you cannot specify different collations per field, or if performing a find with a sort, you cannot use one collation for the find and another for the sort.

If no collation is specified for the collection or for the operations, MongoDB uses the simple binary comparison used in prior versions for string comparisons.

For a collection, you can only specify the collation during the collection creation. Once set, you cannot modify the collection's default collation.

For an example, see Specify Collation.

writeConcern

document

Optional. A document that expresses the write concern for the operation. Omit to use the default write concern.

When issued on a sharded cluster, mongos converts the write concern of the create command and its helper db.createCollection() to "majority".

Access Control

If the deployment enforces authentication/authorization, db.createCollection() requires the following privileges:

Task	Required Privileges
Create a non-capped collection	`createCollection` on the database, or `insert` on the collection to create
Create a capped collection	`convertToCapped` for the collection `createCollection` on the database
Create a view	`createCollection` on the database. However, if the user has the `createCollection` on the database and `find` on the view to create, the user must also have the following additional permissions: `find` on the source collection or view. `find` on any other collections or views referenced in the `pipeline`, if any.

A user with the readWrite built in role on the database has the required privileges to run the listed operations. Either create a user with the required role or grant the role to an existing user.

Behavior

Resource Locking

Changed in version 4.2.

db.createCollection() obtains an exclusive lock on the specified collection or view for the duration of the operation. All subsequent operations on the collection must wait until db.createCollection() releases the lock. db.createCollection() typically holds this lock for a short time.

Creating a view requires obtaining an additional exclusive lock on the system.views collection in the database. This lock blocks creation or modification of views in the database until the command completes.

Prior to MongoDB 4.2, db.createCollection() obtained an exclusive lock on the parent database, blocking all operations on the database and all its collections until the operation completed.

Transactions

Changed in version 4.4.

You can create collections and indexes inside a distributed transaction if the transaction is not a cross-shard write transaction.

To use db.createCollection() in a transaction, the transaction must use read concern "local". If you specify a read concern level other than "local", the transaction fails.

Tip

Examples

Create a Capped Collection

Capped collections have maximum size or document counts that prevent them from growing beyond maximum thresholds. All capped collections must specify a maximum size and may also specify a maximum document count. MongoDB removes older documents if a collection reaches the maximum size limit before it reaches the maximum document count. Consider the following example:

db.createCollection("log", { capped : true, size : 5242880, max : 5000 } )

This command creates a collection named log with a maximum size of 5 megabytes and a maximum of 5000 documents.

See Capped Collections for more information about capped collections.

Create a Time Series Collection

To create a time series collection that captures weather data for the past 24 hours, issue this command:

db.createCollection(
    "weather24h",
    {
       timeseries: {
          timeField: "timestamp",
          metaField: "data",
          granularity: "hours"
       },
       expireAfterSeconds: 86400
    }
)

Create a Collection with Document Validation

Collections with validation compare each inserted or updated document against the criteria specified in the validator option. Depending on the validationLevel and validationAction, MongoDB either returns a warning, or refuses to insert or update the document if it fails to meet the specified criteria.

The following example creates a contacts collection with a JSON Schema validator:

db.createCollection( "contacts", {
   validator: { $jsonSchema: {
      bsonType: "object",
      required: [ "phone" ],
      properties: {
         phone: {
            bsonType: "string",
            description: "must be a string and is required"
         },
         email: {
            bsonType : "string",
            pattern : "@mongodb\.com$",
            description: "must be a string and match the regular expression pattern"
         },
         status: {
            enum: [ "Unknown", "Incomplete" ],
            description: "can only be one of the enum values"
         }
      }
   } }
} )

With the validator in place, the following insert operation fails validation:

db.contacts.insertOne( { name: "Amanda", status: "Updated" } )

The method returns the error:

Uncaught:
MongoServerError: Document failed validation
Additional information: {
  failingDocumentId: ObjectId("61a8f4847a818411619e952e"),
  details: {
    operatorName: '$jsonSchema',
    schemaRulesNotSatisfied: [
      {
        operatorName: 'properties',
        propertiesNotSatisfied: [
          {
            propertyName: 'status',
            description: 'can only be one of the enum values',
            details: [ [Object] ]
          }
        ]
      },
      {
        operatorName: 'required',
        specifiedAs: { required: [ 'phone' ] },
        missingProperties: [ 'phone' ]
      }
    ]
  }
}

To view the validation specifications for a collection, use db.getCollectionInfos().

Tip

Specify Collation

New in version 3.4.

Collation allows users to specify language-specific rules for string comparison, such as rules for lettercase and accent marks.

You can specify collation at the collection or view level. For example, the following operation creates a collection, specifying a collation for the collection (See Collation Document for descriptions of the collation fields):

db.createCollection( "myColl", { collation: { locale: "fr" } } );

This collation will be used by indexes and operations that support collation unless they explicitly specify a different collation. For example, insert the following documents into myColl:

{ _id: 1, category: "café" }
{ _id: 2, category: "cafe" }
{ _id: 3, category: "cafE" }

The following operation uses the collection's collation:

db.myColl.find().sort( { category: 1 } )

The operation returns documents in the following order:

{ "_id" : 2, "category" : "cafe" }
{ "_id" : 3, "category" : "cafE" }
{ "_id" : 1, "category" : "café" }

The same operation on a collection that uses simple binary collation (i.e. no specific collation set) returns documents in the following order:

{ "_id" : 3, "category" : "cafE" }
{ "_id" : 2, "category" : "cafe" }
{ "_id" : 1, "category" : "café" }

Tip

Specify Storage Engine Options

You can specify collection-specific storage engine configuration options when you create a collection with db.createCollection(). Consider the following operation:

db.createCollection(
   "users",
   { storageEngine: { wiredTiger: { configString: "<option>=<setting>" } } }
)

This operation creates a new collection named users with a specific configuration string that MongoDB will pass to the wiredTiger storage engine.

For example, to specify the zlib compressor for file blocks in the users collection, set the block_compressor option with the following command:

db.createCollection(
   "users",
   { storageEngine: { wiredTiger: { configString: "block_compressor=zlib" } } }
)

Back

db.commandHelp

db.createView

db.createCollection()

Definition

Compatibility

Note

Syntax

Access Control

Behavior

Resource Locking

Transactions

Tip

See also:

Examples

Create a Capped Collection

Create a Time Series Collection

Create a Collection with Document Validation

Tip

See also:

Specify Collation

Tip

See also:

Specify Storage Engine Options