Online Redo Logfiles – In Physical Standby

Recently, i was asked, how to add the Online Redo Logfile to the Standby database,
as the parameter log_file_name_convert was set wrong on the Standby database.When i heard the question, i was confused.Though for a moment, and it suddenly hit to my mind
“What is the need of Online Redo Logfiles in the Standby database.The standby database uses Standby Redo Logfiles,not the Online redo logfiles.”

As per the Oracle DataGuard Process Architecture

On the Primary Database, Oracle Data Guard, uses the Log Writer Process(LGWR) or Archiver Process (ARCH) to collect trasaction redo data and ship this data to the standby.On the standby database Oracle Data Guard uses the Remote File Server(RFS) process to receive the redo records from the primary database, the Managed Recover Process(MRP) to apply redo information to the physical standby database.

If the standby database has Standby Redo Log(SRL), then a log switch on the primary database triggers a log switch on the standby database,causing Archiver processes on the standby database to archive the current standby redo log file to an archive log on the standby database.Thereafter,the MRP reads from archive log and apply the redo data to the physical standby database.If, Real Time Apply,is enabled,MRP reads redo data directly from the currrent standby redo log file as it is being filled up by the RFS process.

If the standby database doesn’t have SRL, the archive log files are shipped to the standby database from the primary and then the MRP reads it and applies the redo data to the physical standby

The Online Redo Logfile doesn’t come in picture anywhere in the Physical Standby.Redo,Standby redo and Temp files are managed separately in primary and standby environment.Hence,adding redo into primary would not add same to standby automatically even with correct log_file_name_convert.

Reference – Online Redo Logs on Physical Standby [ID 740675.1]

Its good to be asked🙂

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