Sorry for the late review. I looked through the files and added some comments and suggestions. Let me know once you've had a look at them. In particular, the DuckdbCODDTestOracle is difficult to understand, and I think it will be tough to maintain and extend it in the future. However, I also understand that refactoring this now might be challenging. I'm fine with merging the current state, perhaps after addressing some of the easy issues, but it would also be good to think about what we could improve.