Rails3: If X belong_to Y, how do I display all X regardless of Y?

I am experimenting to create something similar to Twitter.

In my app, posts belong to users, and users has many posts.

Now, I 开发者_StackOverflow中文版know how to display posts of one particular user sorted by submission time.

But I am not sure how to display all posts of all users in one page sorted by submission time.

Any idea?

Post.order(:submission_time)

Something like the following?

def stream
  @post = Post.order("created_at DESC")
end

Or am I misunderstanding you?