title: Elasticsearch reindex with same source and destination
body: <p>I have updated my mappings/synonyms. I would like to reindex my data to the same index.
  I tried _reindex API</p>
  <pre><code>POST _reindex
  {
    &quot;source&quot;: {
      &quot;index&quot;: &quot;test&quot;
    },
    &quot;dest&quot;: {
      &quot;index&quot;: &quot;test&quot;
    }
  }
  </code></pre>
  <p>I get the following error</p>
  <pre><code>{
    &quot;error&quot;: {
      &quot;root_cause&quot;: [
        {
          &quot;type&quot;: &quot;action_request_validation_exception&quot;,
          &quot;reason&quot;: &quot;Validation Failed: 1: reindex cannot write into an index its reading from [test];&quot;
        }
      ],
      &quot;type&quot;: &quot;action_request_validation_exception&quot;,
      &quot;reason&quot;: &quot;Validation Failed: 1: reindex cannot write into an index its reading from [test];&quot;
    },
    &quot;status&quot;: 400
  }
  </code></pre>
  <p>What Am I doing wrong</p>