Catalog update topic updates include both additions and deletions. Even though added objects have a catalog version, deleted objects use the max catalog object version from the update message and not the catalog version that was assigned to the associated object when it was deleted. That works fine assuming the catalog updates do not have gaps (all updates between versions t1 and t2 are included). With the fix for
IMPALA-5058, the semantics of what's included in the catalog updates will change, resulting in metadata inconsistencies if we don't assign the correct versions to deleted objects.
Disclaimer: The above mentioned "versions" indicate the catalog versions set by the catalog server and not the statestore topic versions.