title: Incremental update of specific columns of data in dbt
body: <p>Given a table with say, 20 columns, my current model already inserts all the records into the table. However, I'd like to focus my incremental updates on a couple of columns specifically.</p>
  <p>For example, given the following table model. I'd like to incrementally update only column C with new values when new values are available, not delete and re-insert the whole row which is more costly on indexes / performance perspective.</p>
  <p>Existing:</p>
  <div class="s-table-container">
  <table class="s-table">
  <thead>
  <tr>
  <th>id</th>
  <th>B</th>
  <th>C</th>
  </tr>
  </thead>
  <tbody>
  <tr>
  <td>n1</td>
  <td>X</td>
  <td>1</td>
  </tr>
  <tr>
  <td>n2</td>
  <td>Y</td>
  <td>2</td>
  </tr>
  <tr>
  <td>n3</td>
  <td>Z</td>
  <td>3</td>
  </tr>
  </tbody>
  </table>
  </div>
  <p>New:</p>
  <div class="s-table-container">
  <table class="s-table">
  <thead>
  <tr>
  <th>id</th>
  <th>B</th>
  <th>C</th>
  </tr>
  </thead>
  <tbody>
  <tr>
  <td>n1</td>
  <td>X</td>
  <td>1.2</td>
  </tr>
  <tr>
  <td>n2</td>
  <td>Y</td>
  <td>2.1</td>
  </tr>
  <tr>
  <td>n3</td>
  <td>Z</td>
  <td>3.5</td>
  </tr>
  </tbody>
  </table>
  </div>