title: How do I create a 'feed' to subscribers/followers of an item in PHP/MySQL?
body: <p>We have a group of 'Stores' which also have 'Products' listed in each of them.</p>
  
  <p>As part of an update/notification system, we allow users to 'follow' stores and 'watch' products in stores. If a store posts an update, or gets modified; or if a product changes price, or is modified, etc - we want the notification to appear in the feed of the followers/watchers.</p>
  
  <p>I do not want to have to insert a unique record into a notifications table, because some of these stores/products could have a large number of followers/watchers. We are trying to make sure this scales properly.</p>
  
  <p>On the same note, if a user 'unwatches' or 'unfollows' a product or store respectively, we want those notifications to disappear from that feed of that user.</p>
  
  <p>The last desirable aspect is to have the ability for it to mark a notification as 'viewed' or 'read' when a user has seen it, so we can put a notification bubble in their nav bar.</p>
  
  <p>My difficulty is really coming up with the schema to support this, without the need for excessive inserts into the database table when a new event is posted to a feed.</p>
  
  <p>Can anyone suggest a simple database schema that I could use to support this architecture?</p>