V$dataguard_stats showing 8 hrs delay between Primary and standby

Question

Hello All,
My Primary and standby database are in sync but v$dataguard_stats on standby server showing 8 hrs delay between Primary and standby.
DB Version:11.2.0.1.0
Server :AIX
Primary:
SQL> select /*+ FULL(c) PARALLEL(c, 35) */ distinct SEQUENCE# "Last Sequence Generated" FROM V$ARCHIVED_LOG c WHERE (THREAD#,FIRST_TIME ) IN (select /*+ FULL(c) PARALLEL(c, 35) */ THREAD#,MAX(FIRST_TIME) FROM V$ARCHIVED_LOG c GROUP BY THREAD#);
Last Sequence Generated
                   4521
Standby:
SQL> SELECT  APPL.SEQUENCE# "Last Sequence Applied"
FROM (SELECT THREAD# ,SEQUENCE# FROM V$ARCHIVED_LOG WHERE (THREAD#,FIRST_TIME ) IN (SELECT THREAD#,MAX(FIRST_TIME) FROM V$ARCHIVED_LOG GROUP BY THREAD#)) ARCH,
  2    3  (SELECT THREAD# ,SEQUENCE# FROM V$LOG_HISTORY WHERE (THREAD#,FIRST_TIME ) IN (SELECT THREAD#,MAX(FIRST_TIME) FROM V$LOG_HISTORY GROUP BY THREAD#)) APPL
  4  WHERE ARCH.THREAD# = APPL.THREAD#;
Last Sequence Applied
                 4521
SQL> SELECT ARCH.THREAD# "Thread", ARCH.SEQUENCE# "Last Sequence Received", APPL.SEQUENCE# "Last Sequence Applied", (ARCH.SEQUENCE# - APPL.SEQUENCE#) "Difference"
  2  FROM (SELECT THREAD# ,SEQUENCE# FROM V$ARCHIVED_LOG WHERE (THREAD#,FIRST_TIME ) IN (SELECT THREAD#,MAX(FIRST_TIME) FROM V$ARCHIVED_LOG GROUP BY THREAD#)) ARCH,
  3  (SELECT THREAD# ,SEQUENCE# FROM V$LOG_HISTORY WHERE (THREAD#,FIRST_TIME ) IN (SELECT THREAD#,MAX(FIRST_TIME) FROM V$LOG_HISTORY GROUP BY THREAD#)) APPL
WHERE ARCH.THREAD# = APPL.THREAD#;
  4
    Thread Last Sequence Received Last Sequence Applied Difference
         1                   4521                  4521          0
SQL> select name, 'Hours', to_number(substr(value,5,2)) from v$dataguard_stats where name = 'apply lag' ;
NAME                             'HOUR TO_NUMBER(SUBSTR(VALUE,5,2))
apply lag                        Hours                            8------------------------------------------------------------------>>>Problem area

Answer 1

SQL> SELECT status, error
FROM V$ARCHIVE_DEST_STATUS
WHERE STATUS <> 'DEFERRED' AND STATUS <> 'INACTIVE';  2    3
STATUS    ERROR
VALID
VALID
Standby--Generally in Night it happens that primary and standby 'apply lag' is 8/10/4 hrs .When manually checked database are in sync but  v$dataguard_stats showing difference in hrs
NAME                             'AL
SUBSTR(VALUE,1,12)
apply lag                        ALL
+00 04:11:03
SQL> SQL>   2
NAME                             'SECOND TO_NUMBER(SUBSTR(VALUE,11,2))
apply lag                        Seconds                             3
SQL> SQL>   2
NAME                             'MINUTE TO_NUMBER(SUBSTR(VALUE,8,2))
apply lag                        Minutes                           11
SQL> SQL>   2
NAME                             'HOUR TO_NUMBER(SUBSTR(VALUE,5,2))
apply lag                        Hours                            4
SQL> SQL>   2
NAME                             'DAY TO_NUMBER(SUBSTR(VALUE,2,2))
apply lag                        Days                            0