Create Collection - TechFliez Academy

db.createCollection(name, options) is used to create collection in MongoDB. when you create a document then the collection is automatically created if it does not exist. The collection is like a table in RDBMS.


> db.createCollection("collectionName",options);

collectionName:- is a string type, specifies the name of the collection to be created.

options:- is a document type, specifies the memory size and indexing of the collection. It is an optional parameter.

Field

Type

Description

capped

Boolean

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

autoIndexId

Boolean

Optional. If you specify false then disable the automatic creation of an index on the _id field but now it is deprecated since version 3.2

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.

max

number

(Optional) Specifies the maximum number of documents allowed in the capped collection.

	
> db.createCollection("employees");

Output

{ “ok” : 1 }

How to create Collection through Document?
When you create a document then it checks collection is exists or not if not exists then create automatically.

	
> db.collectionName.insert(objectValue);
> db.users.insert({
	"name":"John",
	"age":35
});

Now, check all collection in the database

	
> show collections

Output

employees

Create Collection – Interview Questions

Q 1: What is a collection in MongoDB?

Ans: A collection is a group of MongoDB documents.

Q 2: How do you create a collection?

Ans: Use db.createCollection("collectionName").

Q 3: Can MongoDB create collections automatically?

Ans: Yes, collections are automatically created when inserting documents.

Q 4: How do you view collections?

Ans: Use show collections.

Q 5: Can you define options while creating collections?

Ans: Yes, options like validation rules and capped collections can be defined.