Create Collection in MongoDB


db.createCollection(<name>, <options>) method is used by MongoDB to create collection.
  • <name> parameter is string type; here we put the name of the collection.
  • <Options> parameter is a document that specifies options about memory size and indexing etc. The options parameter is optional, so you need to specify the only the <name> of the collection. Following is the list of options you can use:


Field

Type

Description

capped
Boolean
 The 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
If true, automatically create an index on the _id field.s Default

size
number
If capped is true it specifies a maximum size in bytes for a capped collection, and then you need to specify this field also.

max
number
This allows the maximum number of documents allowed in the capped collection.


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

Example:
Following I am trying to write the basic syntax for createCollection() method.

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

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

>show collections
mongocollection
system.indexes

Following example shows the syntax of createCollection() method with few important options:

>db.createCollection("mongocollection ", { capped : true, autoIndexID : true, size : 6142800, max : 10000 } )
{ "ok" : 1 }

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

>db.Codefari.insert({"name" : "Codefari"})
>show collections
mongocollection
system.indexes
codefari

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