【Oracle】truncate分区表
分区表是⽣产中常⽤的⼀种表，它可以实现数据的按类存放，极⼤的提⾼了数据的查询及维护。当我们不需要某⼀分区的数据时，可以采⽤truncate来清空分区。实验如下：
SQL>create table t_partition_range(id number,name varchar2(50))
2  partition by range(id)(
3  partition t_range_p1 values less than (10),
4  partition t_range_p2 values less than (20),
5  partition t_range_p3 values less than (30),
6  partition t_range_pmax values less than (maxvalue)
7  );
Table created.
SQL> col PARTITION_NAME for a20;
truncate的数据如何恢复SQL> col HIGH_VALUE for a10;
SQL>select PARTITION_NAME,HIGH_VALUE from user_tab_partitions where table_name='T_PARTITION_RANGE';
PARTITION_NAME    HIGH_VALUE
-------------------- ----------
T_RANGE_P1    10
T_RANGE_P2    20
T_RANGE_P3    30
T_RANGE_PMAX    MAXVALUE
SQL>insert into t_partition_range values (1,'zhangsan');
1 row created.
SQL>insert into t_partition_range values (2,'lisi');
1 row created.
SQL>insert into t_partition_range values (3,'wangwu');
1 row created.
SQL>commit;
Commit complete.
SQL>select*from t_partition_range partition (t_range_p1);
ID NAME
---------- --------------------------------------------------
1 zhangsan
2 lisi
3 wangwu
SQL>alter table t_partition_range truncate partition t_range_p1 update indexes;
Table truncated.
SQL>select*from t_partition_range partition (t_range_p1);
no rows selected
The End!

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