title: Batch query to a GSI in DynamoDB?
body: <p>Is it possible to create a single query on multiple hash key values simultaneously using DynamoDBMapper on a GSI? For example, if I'm trying to get all relevant records in a table Table using a GSI I'd iterate through all my hash key values and make a separate query for each hash key value.</p>
  
  <p>i.e. currently I'm doing</p>
  
  <pre><code>    for (String s : listOfStrings) {
        Attribute thing = new Attribute();
        thing.setSomeField(s);
        DynamoDBQueryExpression&lt;Attribute&gt; queryExpression = 
           new DynamoDBQueryExpression&lt;Attribute&gt;()
              .withHashKeyValues(thing)
              .withIndexName("example-GSI")
              .withConsistentRead(false);
      }
  </code></pre>
  
  <p>But I'd like to do everything in a batch call rather than a for loop.</p>
  
  <p>I've checked the DynamoDBMapper documentation and it appears that there is none, but I was just wondering if anyone out here had any good solution for this case.</p>