title: When would physical operator (e.g. LocalTableScanExec) show no SQL metrics in web UI?
body: <p>Compare the following structured queries and their execution plans in web UI.</p>
  
  <p>I use the same dataset for two different queries.</p>
  
  <pre><code>val names = Seq("Jacek").toDF("name")
  </code></pre>
  
  <p>The following basic query has no SQL metrics in web UI</p>
  
  <pre><code>names.show
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/4uiLZ.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/4uiLZ.png" alt="enter image description here"></a></p>
  
  <p>Surprisingly the query has <strong>number of output rows</strong> metric.</p>
  
  <pre><code>names.count
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/pkwBE.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/pkwBE.png" alt="enter image description here"></a></p>
  
  <p>Why?</p>