in hot standby mode is Repeatable Read.  While performing all
    permanent database writes within Serializable transactions on the
    primary will ensure that all standbys will eventually reach a consistent
    state, a Repeatable Read transaction run on the standby can sometimes
    see a transient state that is inconsistent with any serial execution
    of the transactions on the primary.
   </p><p>
    Internal access to the system catalogs is not done using the isolation
    level of the current trans