create table dropme_t(key, val)
partition by range(key)
(partition p99 values less than (100)
,partition p100 values less than (101)
)as
select rownum+98, case rownum+98 when 100 then 'partition p100' else 'partition p99' end from dual connect by level < 3
;
Table created

select * from dropme_t partition (p100);
       KEY VAL
---------- --------------
       100 partition p100
create table dropme_t_tmp as select * from dropme_t where 1=1
;
Table created

select * from dropme_t_tmp
;
       KEY VAL
---------- --------------
        99 partition p99
       100 partition p100

alter table dropme_t exchange partition (p100) with table dropme_t_tmp
;

alter table dropme_t exchange partition (p100) with table dropme_t_tmp
ORA-14099: Не все строки таблицы могут быть занесены в данную секцию

alter table dropme_t exchange partition (p100) with table dropme_t_tmp WITHOUT VALIDATION
;
Table altered

select * from dropme_t partition (p100)
;
       KEY VAL
---------- --------------
        99 partition p99
       100 partition p100

SQL> 

SQL> select * from dropme_t where key <= 99;
       KEY VAL
---------- --------------
        99 partition p99

SQL> select * from dropme_t where key <= 100;
       KEY VAL
---------- --------------
        99 partition p99
        99 partition p99
       100 partition p100

SQL>