mongodb - 了解 MongoDB 引用

Question

我阅读了 MongoDB 中的数据模型并来到 one to many relationship:

在下面的示例中，这是否意味着书籍文档应该在集合 books 中，MongoDB 将以某种方式将 ID 与数组 books 匹配的文档链接到出版商？还是这种联系只存在于架构师的头脑中？

{
   name: "O'Reilly Media",
   founded: 1980,
   location: "CA",
   books: [12346789, 234567890, ...]
}

{
    _id: 123456789,
    title: "MongoDB: The Definitive Guide",
    author: [ "Kristina Chodorow", "Mike Dirolf" ],
    published_date: ISODate("2010-09-24"),
    pages: 216,
    language: "English"
}

{
   _id: 234567890,
   title: "50 Tips and Tricks for MongoDB Developer",
   author: "Kristina Chodorow",
   published_date: ISODate("2011-05-06"),
   pages: 68,
   language: "English"
}

Answer 1

MongoDB 不会以某种方式将文档与 ids 相匹配的数组书籍链接到 publisher。所以是的，链接只存在于架构师的头脑中

这篇文章只是试图解释如何在 MongoDB 中的文档之间建立一对多关系。

一对多关系在MongoDB中也被进一步分类为one to few和one to squillions。如果场景是one to few，可以使用这样的方法:

{
    name: "O'Reilly Media",
    founded: 1980,
    location: "CA",
    books: [12346789, 234567890, ...]
} {
    _id: 123456789,
    title: "MongoDB: The Definitive Guide",
    author: ["Kristina Chodorow", "Mike Dirolf"],
    published_date: ISODate("2010-09-24"),
    pages: 216,
    language: "English"
} {
    _id: 234567890,
    title: "50 Tips and Tricks for MongoDB Developer",
    author: "Kristina Chodorow",
    published_date: ISODate("2011-05-06"),
    pages: 68,
    language: "English"
}

但实际上，出版商可以出版数百万本书。因此，在那种情况下，这将是 one to squillions 的一个例子。现在存储数百万个 book_ids 可能会使 MongoDB 文档超过 16MB 的大小，这是 MongoDB 文档可以拥有的大小限制。所以在那种情况下最好使用这种方法:

{
    _id: "oreilly",
    name: "O'Reilly Media",
    founded: 1980,
    location: "CA"
} {
    _id: 123456789,
    title: "MongoDB: The Definitive Guide",
    author: ["Kristina Chodorow", "Mike Dirolf"],
    published_date: ISODate("2010-09-24"),
    pages: 216,
    language: "English",
    publisher_id: "oreilly"
} {
    _id: 234567890,
    title: "50 Tips and Tricks for MongoDB Developer",
    author: "Kristina Chodorow",
    published_date: ISODate("2011-05-06"),
    pages: 68,
    language: "English",
    publisher_id: "oreilly"
}