Docs Menu

Docs HomeMongoDB Manual

db.createCollection()

On this page

  • Definition
  • Compatibility
  • Syntax
  • Access Control
  • Behavior
  • Examples
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.

You can use db.createCollection() for deployments hosted in the following environments:

  • MongoDB Atlas: The fully managed service for MongoDB deployments in the cloud

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.

Tip

See also:

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.

validationLevel
Description
"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".

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

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.

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.

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.

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.

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
}
)

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().

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" }

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. See the WiredTiger documentation of collection level options for specific wiredTiger options.

←  db.commandHelp()db.createView() →