You can also use the system utility, Ferret, which is started via the Database Console, to see space usage. Use the ShowSpace command to view space usage (perm, spool, and temporary) at the system level. Use the ShowBlocks command to view the allocation of permanent space at the table and subtable level.
The ShowBlocks command can provide a level of detail that is not available with DBC.TableSize. For example, ShowBlocks can answer “How much perm space is used for a secondary index?” ShowBlocks also provides subtable space information. You can multiply the typical block size times the number of blocks to determine subtable space usage.