I have this query in a plpgsql function, and I want to discard the result set, and I think I need to do that via PERFORM.

query

  WITH RECURSIVE all_descendents AS ( 
  SELECT id, name, parent_id, directory_file_flag, status
    FROM element
    WHERE id = (select pathname_id('/ports/head/' || a_category_name || '/' || a_port_name || '/'))
  UNION
  SELECT E.id, E.name, E.parent_id, E.directory_file_flag, E.status
    FROM element E
    JOIN all_descendents AD
      ON (E.parent_id = AD.id)
)
    SELECT element_add(replace(element_pathname(id), '/ports/head/', '/ports/branches/' || a_branch_name || '/'), directory_file_flag), 
                      replace(element_pathname(id), '/ports/head/', '/ports/branches/' || a_branch_name || '/'), directory_file_flag
      FROM all_descendents
     WHERE status = 'A';

query - fail1

  PERFORM
  WITH RECURSIVE all_descendents AS ( 
  SELECT id, name, parent_id, directory_file_flag, status
    FROM element
    WHERE id = (select pathname_id('/ports/head/' || a_category_name || '/' || a_port_name || '/'))
  UNION
  SELECT E.id, E.name, E.parent_id, E.directory_file_flag, E.status
    FROM element E
    JOIN all_descendents AD
      ON (E.parent_id = AD.id)
)
    SELECT element_add(replace(element_pathname(id), '/ports/head/', '/ports/branches/' || a_branch_name || '/'), directory_file_flag), 
                      replace(element_pathname(id), '/ports/head/', '/ports/branches/' || a_branch_name || '/'), directory_file_flag
      FROM all_descendents
     WHERE status = 'A';
     
     ERROR:  syntax error at or near "PERFORM"
LINE 1: PERFORM
        ^