List the indexes associated with tables in a schema

Simple mode using "LISTAGG".

select table_name,
listagg(index_name, ','
on overflow truncate
) within group (order by index_name) inds
from all_indexes
where owner='HR'
group by table_name;

TABLE_NAME       INDS

---------------- -----------------------------------------------------------------------

COUNTRIES        COUNTRY_C_ID_PK

DEPARTMENTS      DEPT_ID_PK,DEPT_LOCATION_IX

EMPLOYEES        EMP_DEPARTMENT_IX,EMP_EMAIL_UK, EMP_EMP_ID_PK, EMP_JOB_IX,EMP_MANAGER_IX,EMP_NAME_IX

JOBS             JOB_ID_PK

JOB_HISTORY      JHIST_DEPARTMENT_IX,JHIST_EMPLOYEE_IX, JHIST_EMP_ID_ST_DATE_PK,JHIST_JOB_IX

LOCATIONS        LOC_CITY_IX,LOC_COUNTRY_IX,LOC_ID_PK, LOC_STATE_PROVINCE_IX

REGIONS          REG_ID_PK

7 rows selected.