The createCollection() Method - To Create Collection

db.createCollection(name, options) is used to create collection explicitly.

This method is used primarily for creating new capped collections, because MongoDB creates a collection implicitly when the collection is first referenced in a command.

this command is also used to pre-allocate space for an ordinary collection.

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

db.createCollection(<name>, { capped: <boolean>,
                              autoIndexId: <boolean>,
                              size: <number>,
                              max: <number>,
                              storageEngine: <document> } )


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

Parameter	Type	Description
name	string	The name of the collection to create.
options	document	Optional. Configuration options for creating a capped collection or for preallocating space in a new collection.

The options document creates a capped collection or preallocates space for new ordinary collection.
The options document contains the following fields:

Field	Type	Description
capped	boolean	Optional. To create a capped collection, specify true. If you specifytrue, you must also set a maximum size in the size field.
autoIndexId	boolean	Optional. Specify false to disable the automatic creation of an index on the _id field. NOTE: For replica sets, all collections must have autoIndexId set totrue.
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 themax limit, ensure that the size limit, which is required for a capped collection, is sufficient to contain the maximum number of documents.
usePowerOf2Sizes	boolean	Optional. Available for the MMAPv1 storage engine only.
noPadding	boolean	Optional. Available for the MMAPv1 storage engine only. Defaults to false.
storageEngine	document	Optional. Available for the WiredTiger storage engine only.