MongoDB, generic relations to object performance

Question

First of all, i'm newbie for DB design & MongoDB.

I've a DB structure like this,

title
description
[generic_object]
date_created
date_updated
...

generic_object refers to different content types, like these;

food_venue: {lat: long:}

OR

drink_size : 1
drink_brand : "guiness"
drink_type : 3

i'm trying to tell generic objects has different types/jobs.

i've an idea like these, but i dont think its the best way

title
description
type : food or drink
food : {food_id: ... $ref: food model}
drink : {drink_id: ... $ref: drink model}
...

if i add a drink object, food object going to be null or blank.

What is the most best performance way to design this DB in MongoDB (or MongooseJS)?

Answer 1

MongoDB is a "schemaless" database, so your stored documents can be different. In your generic object you can simply save any subdocument you want (food or drink). Anyway, for convenience, you should have a structure in your database, so you can add some extra fields. In your case:

{
  title:"title",
  description:"description",
  generic:
  {
    type:"food",
    field1:"field1",
    field2:"field2",
    field4:"field3",
  }
}

{
  title:"title2",
  description:"description2",
  generic:
  {
    type:"drink",
    otherField1:"field1",
    otherField2:"field2",
  }
}

MongoDB has a limit of 16MB per document, so if you are pretty sure that you will not use that amount of space, you can embed all information on one document.