oracle size of tables in schema
-- Oracle: Size of a table in a tablespace
SELECT
e.owner,
e.segment_name,
e.tablespace_name,
SUM(e.bytes) / 1048576 megs
FROM dba_extents e
WHERE
e.owner = 'xxMY_OWNERxx'
AND e.tablespace_name = 'xxMY_TBSxx'
AND e.segment_name = 'xxMY_TABLExx'
GROUP BY e.owner, e.segment_name, e.tablespace_name
ORDER BY
e.tablespace_name,
e.segment_name;