Oracle 18c changed the checkpointing in a physical standby database (with the side effect of a bug).

  • From: Martin Klier - Performing Databases GmbH <martin.klier@xxxxxxxxxxxxxxxxx>
  • To: Oracle-L Freelists <oracle-l@xxxxxxxxxxxxx>
  • Date: Tue, 13 Aug 2019 15:25:12 +0200 (CEST)

Hi listers, 

just in case you have a similar situation as I had: 
- Oracle 18c 
- Dataguard Physical Stby 
- Log Sequences in question markled as "applied = yes" in v$archived_log 
- but not applied on standby in reality 
- Maybe Archive Gap that could not be resolved by FAL because FRA policies 
deleted the archives due to "applied = yes" 

=> They changed the way how checkpoints work for MRP (now different to primary) 


https://www.usn-it.de/2019/08/13/oracle-database-18c-changed-mrp-checkpointing-from-log-boundary-to-time-based/
 | 
https://www.usn-it.de/2019/08/13/oracle-database-18c-changed-mrp-checkpointing-from-log-boundary-to-time-based/
 ] 

tl/dr: Oracle Dev said: " In 18.1 onward, time-based media recovery checkpoint 
is the default style of checkpoint (it's enabled via the hidden parameter 
_time_based_rcv_ckpt_target=180) meaning that by default, media recovery will 
perform a checkpoint every 180 seconds, instead of at every log boundary. " 

Stay consistent! 
Martin 



-- 
Martin Klier // Performing Databases GmbH 
Managing Partner // Senior DB Consultant 
Oracle ACE Director 

martin.klier@xxxxxxxxxxxxxxxxx // https://www.performing-databases.com ;

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