title: pg_dump, dump options "pre-data", What are the "data definition items" included in "pre_data"?
body: <p>I am reading the <a href="https://www.pgadmin.org/docs/pgadmin4/dev/backup_dialog.html" rel="noreferrer">doc of PG Admin 4 about backup dialog box which uses the <code>pg_dump</code> utility</a>.</p>
  
  <p>In the <strong>dump options</strong> tab, there is a sub-menu <strong>Section</strong> with three switches.</p>
  
  <p>One of the switch is named "pre-data" and the doc explains:</p>
  
  <blockquote>
    <p>Move the switch next to Pre-data to the Yes position to include all data definition items not included in the data or post-data item lists.</p>
  </blockquote>
  
  <p>I don't understand what is included in: </p>
  
  <blockquote>
    <p>all data definition items not included in the data or post-data item lists.</p>
  </blockquote>
  
  <p><strong>What are those "data definition items" included in "pre data"?</strong></p>
  
  <p>Search engines lead me to other Postgresql doc about the <code>pg_dump</code> with exactly the same explanation.</p>