db.createCollection(name, options) is used by MongoDB to create collection.
Where name is name of collection to be created and Options is a document which is use to specify
Name parameter is string type; here we put the name of collection.
Options parameter is document which Specify options about memory size and indexing etc. Options parameter is optional, so you need to specify only name of the collection. Following is the list of options you can use:
Field | Type | Description |
capped | Boolean | 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 size parameter also. |
autoIndexID | Boolean | If true, automatically create index on _id field.s Default |
size | number | If capped is true it’s specify 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 size field of capped collection, then it checks max field.
Example:
Following I am trying to write 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 > |