title: DynamoDB "query" vs "get_item" operations on a partition key or a GSI
body: <ul>
  <li><p>If you perform a "get_item" operation on a dynamodb table, you must provide a partition (primary) key.</p></li>
  <li><p>You are not allowed to perform "get_item" operation on a GSI (global secondary index) even through it acts quite the same as the partition (primary) key.</p></li>
  <li><p>To work with GSI you rather need to "query" the databse.</p></li>
  </ul>
  
  <p><strong><em>So, my question is</em></strong>: is "query" operation with "equals" operator for a GSI is as efficient as "get_item" for the partition key?</p>