title: Set default global postgres transaction isolation level
body: <p>How can I change the default transaction isolation level for the database?</p>
  <p>The <a href="https://www.postgresql.org/docs/12/sql-set-transaction.html" rel="nofollow noreferrer">postgres docs</a> show how to change it per transaction and per session - but not how to alter the default for the database or cluster.</p>
  <p>In MySQL the operation is</p>
  <pre class="lang-sql prettyprint-override"><code>SET GLOBAL TRANSACTION ISOLATION LEVEL READ UNCOMMITTED ;
  </code></pre>
  <p>Is there an equivalent for PostgreSQL?</p>