In Redshift, DROP TABLE ... CASCADE should not be used
        inside a transaction. Redshift doesn't prevent the CASCADE
        part from conflicting with concurrent transactions. If we do
        attempt to drop two tables with CASCADE at once, we'll often
        get the dreaded:

            table was dropped by a concurrent transaction

        So, we need to lock around calls to the underlying
        drop_relation() function.

        https://docs.aws.amazon.com/redshift/latest/dg/r_DROP_TABLE.html

def drop_relation(self, relation):
        """
        In Redshift, DROP TABLE ... CASCADE should not be used
        inside a transaction. Redshift doesn't prevent the CASCADE
        part from conflicting with concurrent transactions. If we do
        attempt to drop two tables with CASCADE at once, we'll often
        get the dreaded:

            table was dropped by a concurrent transaction

        So, we need to lock around calls to the underlying
        drop_relation() function.

        https://docs.aws.amazon.com/redshift/latest/dg/r_DROP_TABLE.html
        """
        with self.connections.fresh_transaction():
            parent = super(RedshiftAdapter, self)
            return parent.drop_relation(relation)