Please execute following command as "sys";
SELECT tablespace_name, owner, segment_type "Object Type",
COUNT(owner) "Number of Objects",
ROUND(SUM(bytes) / 1024 / 1024, 2) "Total Size in MB"
FROM sys.dba_segments
WHERE tablespace_name IN ('ALPERTABLESPACE')
GROUP BY tablespace_name, owner, segment_type
ORDER BY tablespace_name, owner, segment_type;