6: Do not embed fields that have unbound growth

截取的部分原文如下：

 

Comments are often a weird edge case that varies on the application. Comments

should, for most applications, be stored embedded in their parent document. However,

for applications where the comments are their own entity or there are often hundreds

or more, they should be stored as separate documents.

 

As another example, suppose we are creating an application solely for the purpose of

commenting. The image board example in “Tip #3: Try to fetch data in a single

query” on page 5 is like this; the primary content is the comments. In this case, we’d

want comments to be separate documents.

 

 

记得看过一篇文章里说过，单个document是有大小限制的（不过我测试过貌似没有），不过如果遇到post 和 comments这种应该是需要分开存储的，否则数据会有极大极小的倾斜现象。