title: How to get size of PostgreSQL jsonb field?
body: <p>I have a table with jsonb field in table.</p>
  
  <pre><code>CREATE TABLE data.items
  (
    id serial NOT NULL,
    datab jsonb
  )
  </code></pre>
  
  <p>How to get size of this field in a query like this:</p>
  
  <pre><code>select id, size(datab) from data.items
  </code></pre>