Row Cache Object Clones – ORA-00600 [kkdccui2]

We hit a serious problem about 5 months ago when we upgraded one of the development databases from 19.12 to 19.13. Going back to 19.12 solved the problem so definitely for us something introduced in 19.13

Nothing out there at the time on Oracle Support or from other reliable sources.

Our problem happened under row cache load which in particular effected our commit builds when there was heavy dropping and creating of objects across a number of schemas.

Best indication so far is that this is related to the cloning feature of row cache objects, present in 19.13, new feature with aims to automatically create clones of row cache objects if it detects that the object is accessed frequently.

Apparently many bugs related to this feature have already been addressed but suggestion is that disabling the feature might prevent the issue, via the snappily named parameter _bug33046179_kqr_hot_copy_sleep_limit = 0.

Will follow-up with comment on effectiveness.

Addendum:
Good news – parameter seems effective so far but you need to restart the database.
Although you can change the parameter without restarting the database, in our experience you do need to restart if the circumstances around the bug might already have taken effect before you changed the parameter.

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