title: How can I add a new column asynchronously to a mat-table?
body: <p>I can already define the columns using an array, but there is a column that I want to hide, but after a service runs, I want to then show it. I tried the following but the table didn't update:</p>
  
  <pre><code>columnsToShow.push("someColumn")
  </code></pre>
  
  <p>and I have the definition in my table:</p>
  
  <pre><code>&lt;mat-table&gt;
      &lt;ng-container matColumnDef="someColumn"&gt;
          &lt;mat-header-cell *matHeaderCellDef&gt;...&lt;/mat-header-cell&gt;
          &lt;mat-cell *matCellDef="let item"&gt;...&lt;/mat-cell&gt;
      &lt;/ng-container&gt;
  &lt;/mat-table&gt;
  </code></pre>
  
  <p>But the column never appears.</p>