Hi...I dont know how it works with version 5, but
in IDS 9 and 10 once the database server allocates disk space to a tblspace as part of an extent, that space remains dedicated to the tblspace. Even if all extent pages become empty after you delete data, the disk space remains unavailable for use by other tables.
So...when you delete rows in this table, the database server reuses that space to insert new rows into the same table BUT not into other tables !
You have to rebuild the table use any of the following:
ALTER INDEX(with the TO CLUSTER clause) if the table includes an index
UNLOAD and LOAD