observer design pattern in rest aplications

I'm trying to learn design patterns, and I have come with the Observer pattern. I think I understand the concept itself, but I don't see when to use it.

I try to explain myself. I work mostly with web applications, so, stateless applications. Normally, the client makes a petition from the browser (for example, update a record). then the operation is completed.

Let us suppose that I want to notify some persons every time a record is updated. It seems to me the perfect scenario for the Observer patter, but when I think of it, it will end something like:

• user makes petition of update.
• get all the persons that have to be notified.
• put all the persons that have to be notified in the observer.
• make the update. (that also will make the notification for the observer pattern).

but... doing it this way, I have to iterate all the persons that I want to notify twice!

And because its a stateless application, I have to go and get all the persons than needs to be notified every time!

I don't know if the observer pattern is more useful for other types of applications, but I can only think of this pattern in a static form, I mean, making the Observer static.

I know I'm losing something, it's a common and accepted pattern, everyone accept it as a valid solution for this concrete problem. What I am not understanding?