Mongodb模式设计 [英] Mongodb schema design

问题描述

我很困惑，以下情况是最好的格式：

I'm confused, what is the best format for the following case:

Name: Pretty nice hot dog
Stock: 10
Weight: 0.1 grams
Price: 2 dollars

Name: An ordinary dumbbell
Stock: 5
Weight: 4 kilograms
Price: 667.98 yens

This：

db.item.save ({"_id" : 1, "name" : "Pretty nice hot dog", "stock" : 10, "weight" : {"value" : 0.1, "unit" : "gram"}, "price" : {"value" : 2, "unit" : "dollar"}})
db.item.save ({"_id" : 2, "name" : "An ordinary dumbbell", "stock" : 5, "weight" : {"value" : 4, "unit" : "kilogram"}, "price" : {"value" : 667.98, "unit" : "yen"}})

或者这个：

db.unit.save ({"_id" : 1, "name" : "dollar"})
db.unit.save ({"_id" : 2, "name" : "yen"})
db.unit.save ({"_id" : 4, "name" : "gram"})
db.unit.save ({"_id" : 5, "name" : "kilogram"})

db.item.save ({"_id" : 1, "name" : "Pretty nice hot dog", "stock" : 10, "weight" : {"value" : 0.1, "unit" : [new DBRef ("unit", 4)]}, "price" : [new DBRef ("unit", 1)]})
db.item.save ({"_id" : 2, "name" : "An ordinary dumbbell", "stock" : 5, "weight" : {"value" : 4, "unit" : [new DBRef ("unit", 5)]}, "price" : [new DBRef ("unit", 2)]})

字段单位的值是不可变的，我不知道我是否应该把它放在一个单独的集合中。

The values of the field "unit" is immutable, I don't know if I should put it in a separate collection.

谢谢

推荐答案

我会说不。除非您需要从单位（所有项目以一定的成本）查询的灵活性，否则我不会。如果你需要，你可以随时使用map reduce来获得一定成本的所有项目。

I'd say no. Unless you need the flexibility to query from the units (all items with a certain cost), I wouldn't. And if you need to, you can always use map reduce to get all items of a certain cost later on.

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