title: Dynamodb - automatically updating GSI
body: <p>When you update an item on a table, will all items be reflected on the index, including its primary key(s) and projections? The docs mention that it does, but it wasn't specific enough.</p>
  
  <p>Also, the image below shows an example of a composite key made up of <code>Status</code> and <code>Date</code> fields in the table. It was specifically to show how modeling can drastically improve performance. However, I couldn't help but wonder: Does <code>StatusDate</code> update itself when <code>Status</code> changes? How does this work?</p>
  
  <p><a href="https://i.stack.imgur.com/G5ocZ.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/G5ocZ.png" alt="enter image description here"></a></p>