Hi Jan,
this sounds as if the delta merge operation is not executed in this system. This might be due to some merge decision parameters that are set in a way that basically no table would ever get merged.
Please make sure to check the parameters for the merge decision functions and to set them to DEFAULT.
Concerning your measurements: the size information for the tables are updated only when the tables actually got loaded to memory. So these might be off quite a bit, when you look at the numbers w/o ensuring the tables are loaded at that point in time.
- Lars