Time difference between primary and standby database

-- This script should be executed on standby database
-- Time difference between primary and standby database

set serveroutput on;
DECLARE
   v_diff NUMBER := 0;
   v_hrs NUMBER := 0;
   v_min NUMBER := 0;
   v_sec NUMBER := 0;
   p_dte1 DATE;
   p_dte2 DATE;
   date1 long;
   date2 long;
   BEGIN
   date1 := 'select sysdate from dual';
   date2 := 'select max(TIMESTAMP) from v$recovery_progress';
   execute immediate date1 into p_dte1;
   execute immediate date2 into p_dte2;
   v_diff := ABS(p_dte2 - p_dte1);
   v_hrs := TRUNC(v_diff, 0)*24;
   v_diff := (v_diff - TRUNC(v_diff, 0))*24;
   v_hrs := v_hrs + TRUNC(v_diff, 0);
   v_diff := (v_diff - TRUNC(v_diff, 0))*60;
   v_min := TRUNC(v_diff, 0);
   v_sec := TRUNC((v_diff - TRUNC(v_diff, 0))*60, 0);
   DBMS_OUTPUT.put_line(
   TO_CHAR(v_hrs) ||' '||
   TO_CHAR(v_min) ||' '||
   TO_CHAR(v_sec) );
END;
/