MongoDB - Create Collection

In this chapter, we will see how to create a collection using MongoDB.

The createCollection() Method

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

Syntax

The basic syntax of the createCollection() command is as follows:

db.createCollection(name, options)

In the command, name is the name of the collection to be created. Options is a document and is used to specify the configuration of the collection.

Parameters

Parameter	Type	Description
name	String	Name of the collection to be created
options	Document	(Optional) Specify options about memory size and indexing

The options parameter is optional, so you need to specify only the name of the collection. Following is the list of options you can use:

Options

Field	Type	Description
capped	Boolean	(Optional) If true, enables a capped collection. Capped collection is a fixed size collection that automatically overwrites its oldest entries when it reaches its maximum size. If you specify true, you need to specify the size parameter also.
autoIndexId	Boolean	(Optional) If true, automatically creates an index on the _id field. Default value is false.
size	Number	(Optional) Specifies a maximum size in bytes for a capped collection. If capped is true, then you need to specify this field also.
max	Number	(Optional) Specifies the maximum number of documents allowed in the capped collection.

While inserting the document, MongoDB first checks the size field of the capped collection, then it checks the max field.

Examples

The basic syntax of the createCollection() method without options is as follows:

> use test
switched to db test
> db.createCollection("mycollection")
{ "ok" : 1 }

You can check the created collection by using the command show collections.

> show collections
mycollection
system.indexes

The following example shows the syntax of the createCollection() method with a few important options:

> db.createCollection("mycol", { capped: true, autoIndexId: true, size: 6142800, max: 10000 })
{
   "ok" : 0,
   "errmsg" : "BSON field 'create.autoIndexId' is an unknown field.",
   "code" : 40415,
   "codeName" : "Location40415"
}

In MongoDB, you don't need to create a collection explicitly. MongoDB creates the collection automatically when you insert some document.

> db.tutorialspoint.insert({"name" : "tutorialspoint"})
WriteResult({ "nInserted" : 1 })
> show collections
mycol
mycollection
system.indexes
tutorialspoint

Collection Creation Diagram

Command Summary

Command	Description
db.createCollection(name, options)	Create a collection with the specified name and options
show collections	List all collections in the current database
db.collection.insert(document)	Insert a document into a collection, creating the collection if it does not exist