I think you are using different interpretations of &quot;you&quot;.<p>If you do:<p><pre><code>  update aTable
  set loginInfo = loginInfo - &#x27;lastLogin&#x27;
</code></pre>
where &#x27;loginInfo&#x27; is a jsonb column, you, the programmer, need not write out the parts of the data to keep. PostgreSQL still sees this as &#x27;read column, evaluate expression, write result&#x27;, so it will read and write the entire jsonb value.