title: Default isolation level for transaction (@atomic) with Django and PostgreSQL
body: <p>I was wondering what's the default isolation level when using Django with PostgreSQL database. <em>Serializable Isolation</em>? (<a href="https://www.postgresql.org/docs/9.1/static/transaction-iso.html#XACT-SERIALIZABLE" rel="noreferrer">https://www.postgresql.org/docs/9.1/static/transaction-iso.html#XACT-SERIALIZABLE</a>)</p>
  
  <p>There is a discussion about MySQL (<a href="https://stackoverflow.com/questions/2280779/django-transaction-isolation-level-in-mysql-postgresql">Django transaction isolation level in mysql &amp; postgresql</a>) but despite its name is doesn't seem to discuss PostgreSQL</p>
  
  <p>Thanks!</p>