db.createCollection()

Definition定义

db.createCollection(name, options)

Creates a new collection. 创建新集合。For views, see db.createView().有关视图，请参阅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:由于MongoDB在命令中首次引用集合时会隐式创建集合，因此此方法主要用于创建使用特定选项的新集合。例如，您可以使用db.createCollection()创建一个：

• Capped collection.封顶集合。
• Clustered collection.群集集合。
• New collection that uses document validation.使用文档验证的新集合。

db.createCollection() is a wrapper around the database command create.是数据库命令create的包装器。

The db.createCollection() method has the following prototype form:db.createCollection()方法具有以下原型形式：

db.createCollection( <name>,
   {
     capped: <boolean>,
     timeseries: {                  // Added in MongoDB 5.0
        timeField: <string>,        // required for time series collections
        metaField: <string>,
        granularity: <string>,
        bucketMaxSpanSeconds: <number>,  // Added in MongoDB 6.3
        bucketRoundingSeconds: <number>  // Added in MongoDB 6.3
     },
     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:db.createCollection()方法具有以下参数：

Parameter参数	Type类型	Description描述
name	string	The name of the collection to create. 要创建的集合的名称。See Naming Restrictions.请参见命名限制。
options	document	Optional.可选的。Configuration options for creating a: 用于创建的配置选项： Capped collection封顶集合 Clustered collection群集集合 View视图

The options document contains the following fields:options文档包含以下字段：

Field字段	Type类型	Description描述
capped	boolean	Optional.可选的。To create a capped collection, specify true. 若要创建封顶集合，请指定true。If you specify true, you must also set a maximum size in the size field.如果指定true，则还必须在size字段中设置最大大小。
timeseries.timeField	string	Required when creating a time series collection. 创建时间序列集合时需要。The name of the field which contains the date in each time series document. 包含每个时间序列文档中的日期的字段的名称。Documents in a time series collection must have a valid BSON date as the value for the timeField.时间序列集合中的文档必须具有有效的BSON日期作为timeField的值。
timeseries.metaField	string	Optional.可选的。The name of the field which contains metadata in each time series document. 包含每个时间序列文档中的元数据的字段的名称。The metadata in the specified field should be data that is used to label a unique series of documents. 指定字段中的元数据应该是用于标记一系列唯一文档的数据。The metadata should rarely, if ever, change.元数据应该很少更改（如果有的话）。 The name of the specified field may not be _id or the same as the timeseries.timeField. 指定字段的名称不能为_id，也不能与timeseries.timeField相同。The field can be of any type except array. 字段可以是除数组之外的任何类型。
timeseries.granularity	string	Optional, do not use if setting bucketRoundingSeconds and bucketMaxSpanSeconds. 可选，如果设置了bucketRoundingSeconds和bucketMaxSpanSeconds，则不要使用。Possible values are seconds (default), minutes, and hours.可能的值包括seconds（默认值）、minutes和hours。 Set granularity to the value that most closely matches the time between consecutive incoming timestamps. 将granularity设置为与连续传入时间戳之间的时间最匹配的值。This improves performance by optimizing how MongoDB internally stores data in the collection.这通过优化MongoDB在集合中内部存储数据的方式来提高性能。 For more information on granularity and bucket intervals, see Set Granularity for Time Series Data. 有关粒度和存储段间隔的更多信息，请参阅设置时间序列数据的粒度。
timeseries.bucketMaxSpanSeconds	integer	Optional, used with bucketRoundingSeconds as an alternative to granularity. Sets the maximum time between timestamps in the same bucket. 可选，与bucketRoundingSeconds一起使用，作为granularity的替代方案。设置同一存储桶中时间戳之间的最长时间。Possible values are 1-31536000. 可能的值为1-31536000。If you set bucketMaxSpanSeconds, you must set bucketRoundingSeconds to the same value.如果设置了bucketMaxSpanSeconds，则必须将bucketRoundingSeconds设置为相同的值。 To downgrade below MongoDB 6.3, you must either modify the collection to use the corresponding granularity value, or drop the collection. 要降级到MongoDB 6.3以下，您必须修改集合以使用相应的granularity值，或者删除集合。For details, see collMod. 有关详细信息，请参阅collMod。
timeseries.bucketRoundingSeconds	integer	Optional, used with bucketMaxSpanSeconds as an alternative to granularity. 可选，与bucketMaxSpanSeconds一起使用，作为granularity的替代方案。Sets the number of seconds to round down by when MongoDB sets the minimum timestamp for a new bucket. 设置MongoDB为新bucket设置最小时间戳时需要四舍五入的秒数。Must be equal to bucketMaxSpanSeconds.必须等于bucketMaxSpanSeconds。 For example, setting both parameters to 1800 rounds new buckets down to the nearest 30 minutes. 例如，将两个参数都设置为1800会将新的存储桶循环到最接近的30分钟。If a document with a time of 2023-03-27T18:24:35Z does not fit an existing bucket, MongoDB creates a new bucket with a minimum time of 2023-03-27T18:00:00Z and a maximum time of 2023-03-27T18:30:00Z. 如果时间为2023-03-27T18:24:35Z的文档不适合现有bucket，MongoDB会创建一个新bucket，最小时间为2023-03-27T18:00:00Z，最大时间为2023-03-27T18:30:00Z。
expireAfterSeconds	number	Optional.可选的。Specifies the seconds after which documents in a time series collection or clustered collection expire. MongoDB deletes expired documents automatically.指定时间序列集合或聚集集合中的文档过期的秒数。MongoDB会自动删除过期文档。 For clustered collections, the documents are deleted automatically based on the clustered index key _id and the values must be date types. 对于聚集集合，文档将根据聚集索引键_id自动删除，并且值必须是日期类型。See TTL Indexes. 请参阅TTL索引。
clusteredIndex	document	Starting in MongoDB 5.3, you can create a collection with a clustered index. 从MongoDB 5.3开始，您可以创建一个具有聚集索引的集合。Collections created with a clustered index are called clustered collections.使用聚集索引创建的集合称为聚集集合。 See Clustered Collections.请参见聚集集合。 clusteredIndex has the following syntax: 具有以下语法： clusteredIndex: { key: { <string> }, unique: <boolean>, name: <string> } Field字段 Description描述 key Required. 必要的。The clustered index key field. Must be set to { _id: 1 }. 聚集索引键字段。必须设置为{ _id: 1 }。The default value for the _id field is an automatically generated unique object identifier, but you can set your own clustered index key values._id字段的默认值是自动生成的唯一对象标识符，但您可以设置自己的聚集索引键值。 unique Required. 必要的。Must be set to true. 必须设置为true。A unique index indicates the collection will not accept inserted or updated documents where the clustered index key value matches an existing value in the index.唯一索引表示集合不接受聚集索引键值与索引中现有值匹配的插入或更新文档。 name Optional.可选的。A name that uniquely identifies the clustered index.唯一标识聚集索引的名称。 New in version 5.3. 5.3版新增。
changeStreamPreAndPostImages	document	Optional.可选的。 Starting in MongoDB 6.0, you can use change stream events to output the version of a document before and after changes (the document pre- and post-images): 从MongoDB 6.0开始，您可以使用更改流事件来输出更改前后文档的版本（文档前后映像）： The pre-image is the document before it was replaced, updated, or deleted. 预映像是在文档被替换、更新或删除之前的文档。There is no pre-image for an inserted document.插入的文档没有预映像。 The post-image is the document after it was inserted, replaced, or updated. 张贴映像是插入、替换或更新后的文档。There is no post-image for a deleted document.已删除的文档没有发布映像。 Enable changeStreamPreAndPostImages for a collection using db.createCollection(), create, or collMod. changeStreamPreAndPostImages has the following syntax: 具有以下语法： changeStreamPreAndPostImages: { enabled: <boolean> } enabled Description描述 true Enables change stream pre- and post-images for a collection.启用集合的更改流前映像和后映像。 false Disables change stream pre- and post-images for a collection.禁用集合的更改流前映像和后映像。 For complete examples with the change stream output, see Change Streams with Document Pre- and Post-Images.有关更改流输出的完整示例，请参阅文档前后映像的更改流。 For a db.createCollection() example on this page, see Create a Collection with Change Stream Pre- and Post-Images for Documents.有关此页上的db.createCollection()示例，请参阅创建一个具有文档更改流前后映像的集合。 New in version 6.0. 6.0版新增。
size	number	Optional.可选的。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. 指定带上限集合的最大大小（以字节为单位）。一旦有上限的集合达到其最大大小，MongoDB就会删除旧文档，为新文档腾出空间。The size field is required for capped collections and ignored for other collections.size字段对于带上限的集合是必需的，而对于其他集合则被忽略。
max	number	Optional.可选的。The maximum number of documents allowed in the capped collection. 上限集合中允许的最大文档数。The size limit takes precedence over this limit. size限制优先于此限制。If a capped collection reaches the size limit before it reaches the maximum number of documents, MongoDB removes old documents. 如果一个有上限的集合在达到最大文档数之前就达到了size限制，MongoDB就会删除旧文档。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.如果您喜欢使用max限制，请确保有上限集合所需的size限制足以包含最大数量的文档。
storageEngine	document	Optional.可选的。Available for the WiredTiger storage engine only.仅适用于WiredTiger存储引擎。 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: 允许用户在创建集合时按每个集合指定存储引擎的配置。storageEngine选项的值应采用以下形式： { <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. 创建集合时指定的存储引擎配置将在复制期间进行验证并记录到oplog中，以支持具有使用不同存储引擎的成员的复制副本集。 Tip See also: 另请参阅： Specify Storage Engine Options指定存储引擎选项
validator	document	Optional.可选的。Allows users to specify validation rules or expressions for the collection.允许用户为集合指定验证规则或表达式。 The validator option takes a document that specifies the validation rules or expressions. validator选项接受一个指定验证规则或表达式的文档。You can specify the expressions using the same operators as the query operators with the exception of $near, $nearSphere, $text, and $where.您可以使用与查询运算符相同的运算符指定表达式，但$near、$nearSphere、$text和$where除外。 To learn how to create a collection with schema validation, see Specify JSON Schema Validation. 要了解如何使用模式验证创建集合，请参阅指定JSON模式验证。
validationLevel	string	Optional.可选的。Determines how strictly MongoDB applies the validation rules to existing documents during an update. 确定MongoDB在更新期间对现有文档应用验证规则的严格程度。 validationLevel Description描述 "off" No validation for inserts or updates.没有对插入或更新进行验证。 "strict" Default默认值。 Apply validation rules to all inserts and all updates.将验证规则应用于所有插入和所有更新。 "moderate" Apply validation rules to inserts and to updates on existing valid documents. 将验证规则应用于现有有效文档的插入和更新。Do not apply rules to updates on existing invalid documents.不要将规则应用于现有无效文档的更新。 To see an example that uses validationLevel, see Specify Validation Level for Existing Documents.要查看使用validationLevel的示例，请参阅指定现有文档的验证级别。
validationAction	string	Optional.可选的。Determines whether to error on invalid documents or just warn about the violations but allow invalid documents to be inserted. 确定是在无效文档上出错，还是仅警告冲突，但允许插入无效文档。 Important Validation of documents only applies to those documents as determined by the validationLevel. 文件的验证仅适用于由validationLevel确定的那些文件。 To see an example that uses validationAction, see Choose How to Handle Invalid Documents. 要查看使用validationAction的示例，请参阅选择如何处理无效文档。
indexOptionDefaults	document	Optional.可选的。Allows users to specify a default configuration for indexes when creating a collection.允许用户在创建集合时为索引指定默认配置。 The indexOptionDefaults option accepts a storageEngine document, which should take the following form: indexOptionDefaults选项接受storageEngine文档，该文档应采用以下形式： { <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. 创建索引时指定的存储引擎配置将在复制期间进行验证并记录到oplog中，以支持具有使用不同存储引擎的成员的复制副本集。
viewOn	string	The name of the source collection or view from which to create a view. 要从中创建视图的源集合或视图的名称。For details, see db.createView().有关详细信息，请参阅db.createView()。
pipeline	array	An array that consists of the aggregation pipeline stage(s). 由聚合管道阶段组成的数组。 db.createView() creates a view by applying the specified pipeline to the viewOn collection or view. 通过将指定的pipeline应用于viewOn集合或视图来创建视图。For details, see db.createView().有关详细信息，请参阅db.createView()。
collation	document	Specifies the default collation for the collection.指定集合的默认排序规则。 collation allows users to specify language-specific rules for string comparison, such as rules for lettercase and accent marks.允许用户为字符串比较指定特定于语言的规则，例如字母大小写和重音标记的规则。 The collation option has the following syntax: collation选项具有以下语法： 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. 指定排序规则时，locale字段是必需的；所有其他排序规则字段都是可选的。For descriptions of the fields, see Collation Document.有关字段的说明，请参阅排序规则文档。 If you specify a collation at the collection level: 如果在集合级别指定排序规则： Indexes on that collection will be created with that collation unless the index creation operation explicitly specify a different collation.除非索引创建操作明确指定了其他排序规则，否则将使用该排序规则创建该集合上的索引。 Operations on that collection use the collection's default collation unless they explicitly specify a different collation.对该集合的操作使用集合的默认排序规则，除非它们明确指定了不同的排序规则。 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.不能为一个操作指定多个排序规则。例如，不能为每个字段指定不同的排序规则，或者如果使用排序执行查找，则不能为查找使用一个排序规则，为排序使用另一个排序顺序。 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.如果没有为集合或操作指定排序规则，MongoDB将使用以前版本中使用的简单二进制比较进行字符串比较。 For a collection, you can only specify the collation during the collection creation. Once set, you cannot modify the collection's default collation.对于集合，只能在创建集合期间指定排序规则。一旦设置，就不能修改集合的默认排序规则。 For an example, see Specify Collation. 有关示例，请参阅指定排序规则。
writeConcern	document	Optional.可选的。A document that expresses the write concern for the operation. Omit to use the default write concern.表示操作的写入关注的文档。忽略使用默认的写入关注。 When issued on a sharded cluster, mongos converts the write concern of the create command and its helper db.createCollection() to "majority". 当在分片集群上发出时，mongos将create命令及其助手db.createCollection()的写入关注转换为"majority"。

Access Control访问控制

If the deployment enforces authentication/authorization, db.createCollection() requires the following privileges:如果部署强制执行身份验证/授权，则db.createCollection()需要以下权限：

A user with the readWrite built in role on the database has the required privileges to run the listed operations. 在数据库中具有内置readWrite角色的用户具有运行所列操作所需的权限。Either create a user with the required role or grant the role to an existing user.创建一个具有所需角色的用户，或者将该角色授予现有用户。

Behavior行为

Examples实例

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

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

db.createCollection(
    "weather24h",
    {
       timeseries: {
          timeField: "timestamp",
          metaField: "data",
          bucketMaxSpanSeconds: "3600",
          bucketRoundingSeconds: "3600"
       },
       expireAfterSeconds: 86400
    }
)

db.createCollection(
   "stocks",
   { clusteredIndex: { "key": { _id: 1 }, "unique": true, "name": "stocks clustered key" } }
)

db.createCollection(
   "temperatureSensor",
   { changeStreamPreAndPostImages: { enabled: true } }
);

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

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

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

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

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

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