code: def _check_db_exists(self, instance):
          
  
          dsn, host, username, password, database, driver = self._get_access_info(instance, self.DEFAULT_DB_KEY)
          context = "{} - {}".format(host, database)
          if self.existing_databases is None:
              cursor = self.get_cursor(instance, None, self.DEFAULT_DATABASE)
  
              try:
                  self.existing_databases = {}
                  cursor.execute(DATABASE_EXISTS_QUERY)
                  for row in cursor:
                      self.existing_databases[row.name] = True
  
              except Exception as e:
                  self.log.error("Failed to check if database {} exists: {}".format(database, e))
                  return False, context
              finally:
                  self.close_cursor(cursor)
  
          return database in self.existing_databases, context
docs: Check if the database we're targeting actually exists
          If not then we won't do any checks
          This allows the same config to be installed on many servers but fail gracefully