您如何优化构造MongoDB数据库以获取用户的所有属性？

Question

I'm building an app where a user object has multiple game objects. What would be the proper strategy for fetching all of a user's games from a mongoDB database?

As far as I can tell I have 2 options:

1. Give users a game property that is an array of ids of games that the user has and then fetch each game individually

eg example user

{
  _id: '1342',
  name: 'Dave',
  games: [
    '12345678',
    'fgnhe45rnd',
  ],
}

example game

{
  _id: '12345678',
  name: 'Fluxx',
}

2. The opposite. Give each game a users property that is an array of ids of users that own that game. Then fetch all games that have a specific user's id.

eg example user

{
  _id: '1342',
  name: 'Dave',
}

example game

{
  _id: '12345678',
  name: 'Fluxx',
  users: [
    '1342',
    '5783',
  ],
}

Any advice is appreciated. Thank you.

Answer 1

如果您需要用户游戏，则应使用1。例如，我需要kevin的游戏：您可以使用2获得kevin的游戏。

Answer 2

Use Case

1. A user object has multiple game objects
2. To fetching all of a user's games

I will suggest you use the first option .

Example user

{
  _id: '1342',
  name: 'Dave',
  games: [
    '12345678',
    'fgnhe45rnd',
  ],
}

Example game

{
  _id: '12345678',
  name: 'Fluxx',
}

Reason

As you mentioned in the use case, you are fetching all of a user's games.

First Option

So if you are fetching all of Dave's game, you only need to get Dave's list of games then refer each game to its data. This is 1+n fetch where n is number of game Dave has .

Second Option

If you use the second option, you will need to go through every single game to check if users list in the game contains Dave. And then you have to record the data only if Dave is in the list. This is N fetch where N is total number of games in the database .

In general, N is larger than n+1.