Dataguard

step 1:
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Check the number of gap between Last sequence Received and last sequence applied. if it gives any number check the MRP process is running.


SELECT ARCH.THREAD# "Thread", ARCH.SEQUENCE# "Last Sequence Received", APPL.SEQUENCE# "Last Sequence Applied", (ARCH.SEQUENCE# - APPL.SEQUENCE#) "Difference"
          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,
         (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#
          ORDER BY 1;




To check MRP process is running or not:

select process,client_process,status,thread#,sequence#,block#,blocks
from v$managed_standby;




To put database in recovery mode:

startup mount;
alter database recover managed standby database disconnect from session;