[Question] drop_namespace behavior inconsistent for different catalogs

[dentiny]

When checking drop_namespace implementation, I found different catalogs doesn't conform to the same behavior.
For example, when we delete parent namespace, what would happen to the children namespaces?

• memory catalog and s3 table catalog delete children catalog as well
• while sql catalog doesn't touch children catalogs

I understand the reason behind:

• For storage backend which support "directory"-like structure, it makes sense (and is easier) to clean them up all together;
• While for object-oriented backend, it's expensive to recursively traverse down to the leaf namespace.

I would like to know, if the team think it's ok to specify clearly in the documentation on the behavior?
Or it's better to leave it as it as, meaning, all undocumented behavior are undefined and implementation-dependent.
Thank you!

[liurenjie1024]

This seems to be a common problem also in java/python implementation, and there is no clear answer to that. Personally I think it's reasoanble to unify behaviors.

[dentiny]

Another benefit is we could share tests among catalogs right now they are scattered around

[liurenjie1024]

There was some issue there: #519

[dentiny]

Thanks! It would be nice if you or others who are senior in iceberg field to help consolidate the behavior to reduce confusion :)