Total Space OLAP option Schemas are Occupying (every object) by schema.

Basically any schema containing Multidimensional Datatypes (Analytic Workspaces) will be listed here. All others will be ignored.

set pages500 lines110
bre on REPORT;
comp sum lab "Total:" of objects on REPORT;
comp sum lab "Total:" of mb on REPORT;
col owner format a15 heading "Owner"
col objects format 99,999,990 heading "Objects"
col mb format 99,999,999,990.00 heading "On Disk MB"

select owner, count(distinct segment_name) objects, round(sum(bytes)/1024/1024,2) MB
from dba_segments where owner in (select owner from dba_aws) group by owner order by mb desc;

Owner...............Objects.........On Disk MB
--------------- ----------- ------------------
SCOTT6....................4...........7,037.19
SCOTT1....................4...........6,977.25
FOOD.....................12...........6,970.88
SCOTT4....................4...........6,952.31
SCOTTM...................51...........3,961.13
SYS...................1,554...........1,133.63
AWOLAPDL..................4.............270.50
PESCIJ2..................12.............269.19
SCOTT5....................4.............101.69
AWTSTOLAP.................8..............56.44
SCOTT7....................4..............30.63
SCOTT2....................4..............29.63
SCOTT3....................4..............12.63
................----------- ------------------
Total:................1,669..........33,803.10

Total Space ALL Schemas are Occupying (every object) on Database

set pages500 lines110
bre on REPORT;
comp sum lab "Total:" of objects on REPORT;
comp sum lab "Total:" of mb on REPORT;
col owner format a15 heading "Owner"
col objects format 99,999,990 heading "Objects"
col mb format 99,999,999,990.00 heading "On Disk MB"

select owner, count(distinct segment_name) objects, round(sum(bytes)/1024/1024,2) MB
from dba_segments group by owner order by mb desc;