Bug 29056767  STANDBY: Datafiles Checkpoint not Updated at Standby Database when Media Recover is running

Affects:

Product (Component)	Oracle Server (Rdbms)
Range of versions believed to be affected	(Not specified)
Versions confirmed as being affected	18.1.0
Platforms affected	Generic (all / most platforms affected)

Fixed:

The fix for 29056767 is first included in

20.1.0 19.4.0.0.190716 (Jul 2019) Database Release Update (DB RU) 18.18.0.0.DBRU:220219 (FEB 2022) Database Release Update (DB RU) 18.8.0.0.191015 (Oct 2019) Database Release Update (DB RU)

Interim patches may be available for earlier versions - click here to check.

Description

On a Physical Standby database, media recovery not regularly updating the checkpoint scn and time stored in each datafile header. 
 
This problem only happens in oracle version 18.1 onwards.
 
Standby media recovery is running, and it's applying successive log seq#'s,
but the checkpoint scn and time stored each datafile header doesn't change.
 
NOTE: the checkpoint in the datafile headers can be monitored by:
 
  select to_char(sysdate,'HH24:MI:SS'), file#, checkpoint_change#,
      to_char(checkpoint_time,'HH24:MI:SS') from v$datafile_header;
 
A level 1 incremental backup on the standby may skip all the datafiles.
 
Another impact of this bug is that if media recovery suddenly aborts for some other reason (eg due to a "shutdown abort" of the instance)
then the next media recovery session may try to start scanning redo from much further back in time than necessary, and if that redo is
unavailable, V$MANAGED_STANDBY would show MRP0 status is WAIT_FOR_GAP, alert log file will show 'FAL: Failed to request gap sequence'
 
Workaround
On the standby, 
 
 set:  alter system set "_time_based_rcv_ckpt_target"=0;
 
NOTE: restart media recovery for it to pick up the new parameter value.
NOTE: this parameter can also be proactively set on the primary, so it
      is ready in case it becomes the standby in the future
 

References

Bug:29056767 (This link will only work for PUBLISHED bugs)
Note:245840.1 Information on the sections in this article