Many thanks to a German customer for showing me this tiny behavior change with Oracle Database RU 19.4.0. From this RU on the well known ORA-1555 won’t get reported into alert.log anymore since 19.4.0. But if you still like to see the “
snapshot too old” error, then you can use a workaround.
Why has this been changed?
Actually this is something I don’t understand completely. It may be just a side effect. Unpublished fix bug 29424999 – DUMP MINIMAL DIAGNOSTICS BY DEFAULT IN CASE OF ORA-01555 IN ADW/ATP ENV has been included into 19.4.0 to dump diagnostic information (I guess, into traces). But the bug doesn’t give an indication that the ORA-1555 disappears from the alert.log as well.
Where is this described?
Instead in this case, MOS Note: 2656624.1 – ORA-01555 is Not Reported in Alert Log Since RU 18.104.22.168.0 gives you way more information. For instance, the (customer confirmed) behavior that an ORA-1555 does not show up in the alert.log anymore.
The customer questioned here why we introduce such a behavior change in an RU.
What is different since 19.4.0?
If you get an ORA-1555, you won’t find it in the alert.log anymore but rather get a trace file. If you’d like to revert to the “old” behavior, you need to set ONLY ONE of the following events:
alter system set event='10442 trace name context forever, level 10' COMMENT=' Bug 29424999 - Bring back ORA-1555 to my alert.log - 2020_09_10' scope=spfile sid='*';
alter system set event='55521 trace name context forever, level 1' COMMENT=' Bug 29424999 - Bring back ORA-1555 to my alert.log - 2020_09_10' scope=spfile sid='*' ;
Then the behavior will be as it was before 19.4.0.
And remember to set underscores and events always with a comment as otherwise you potentially won’t remember (or your colleagues may not understand) why and when it has been added. This makes it much easier to maintain such special settings.
When is the fix included? [Nov 19. 2020]
With RU 19.9.0 (October 2020) and RURs 19.8.1 and 19.7.2 a fix for Bug 31888148 got included. This bug got filed to report the ORA-1555 to the alert.log again as before.
See also: MOS Note: 2523220.1 – Database 19 Release Updates and Revisions Bugs Fixed Lists and search for “31888148”:
More Information and Links
- MOS Note: 2656624.1 – ORA-01555 is Not Reported in Alert Log Since RU 22.214.171.124.0
- Unpublished bug 29424999 – DUMP MINIMAL DIAGNOSTICS BY DEFAULT IN CASE OF ORA-01555 IN ADW/ATP ENV
- Unpublished bug 31888148 – ORA-01555 IS NOT REPORTED IN ALERT LOG AFTER RU 126.96.36.199.0