26ai Alert Log Size – Keep Learning Keep Living

Hi,

Oracle database writes alert logs into 2 different location with different file formats. To find diag alert location:

select * from v$diag_info where name ='Diag Alert';

1	select * from v$diag_info where name ='Diag Alert';

in this directory, you will find XML files for alert logs. Oracle always writes into log.xml file. Whenever it exceeds a certain threshold, log.xml file is renamed as log_2.xml. on the next time, it will be renamed as log_3.xml and so on.

Second alert log file is alert_<SID>.log file. it is a text base file and it is in Diag Trace location:

select * from v$diag_info where name ='Diag Trace';

1	select * from v$diag_info where name ='Diag Trace';

log.xml file has more information like container data, message group etc. actually V$diag_alert_ext view is readin xml files (not alert log file).

What I find out recently is on 26ai file size threshold has been changed. before 26ai, every 11MB log.xml file were switched. After 26ai threshold is increased to 51MB. I am not sure if there is a way to control it. I searched a little bit but couldn’t find a way to increase or decrease the threshold.

I would prefer lower threshold because, I mostly read log.xml file in database via xmltable which makes it faster than v$diag_alert_ext view but when the size is increased, it took more time and v$diag_alert_ext becomes more efficient.

just some info that I discovered, wish you a healthy beautiful day.

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