conn / as sysdba
drop user jon cascade;
grant dba to jon identified by jon;
conn jon/jon
create table t1 as select * from all_objects;
create index i1 on t1(object_name);

alter index i1 rebuild online;


--in another session, before/during/after the index rebuild:
conn jon/jon
select segment_name,segment_type,bytes from user_segments;