In the MyStatus application, we'll begin by creating a timeline of status updates for each user. Users can view their friends' status updates by accessing the timeline of the friend in question.
The user timeline requires a new level of organization, which we didn't see in the users table that we created in the previous chapter. Specifically, we have two requirements:
- Rows (individual status updates) should be logically grouped by a certain property (the user who created the update)
- Rows should be accessible in a sorted order (in this case, by creation date)
Fortunately, compound primary keys provide exactly these qualities.
