mongodb - Mongoid embed_one and has_one -

recently working on mongoid, i'm confused embed_one in mongoid same has_one? if no, what's difference , examples?

first of all, read mongoid documentation relations!

mongoid embedded 1-1

one 1 relationships children embedded in parent document defined using mongoid's embeds_one , embedded_in macros.

mongoid refrence 1-1

one 1 relationships children referenced in parent document defined using mongoid's has_one , belongs_to macros.

from mongodb documentation :

embeds_one benefits against has_one

• generally better performance read operations.
• the ability request , retrieve related data in single database operation.

large data problem :

embedding related data in documents, can lead situations documents grow after creation. document growth can impact write performance , lead data fragmentation. furthermore, documents in mongodb must smaller maximum bson document size.

that happens when using embeds_many.

embeds_one embeds model inside model has_one save reference in model.

mongodb save document in database way (from mongodb examples)

reference 1-1 :

{    _id: "joe",    name: "joe bookreader" }  {    patron_id: "joe",    street: "123 fake street",    city: "faketon",    state: "ma"    zip: 12345 } 

embedded 1-1

{    _id: "joe",    name: "joe bookreader",    address: {               street: "123 fake street",               city: "faketon",               state: "ma"               zip: 12345             } }