丢弃超过2个月的分区

Question

我有一个基于日期字段的分区表.现在,我必须编写一个程序来删除超过2个月的所有分区,即test_date超过2个月.我该怎么做？

create table test_table
(
test_id number,
test_date date,
constraint pk_test primary key (test_id)
)
partition by range (test_date)
(
PARTITION pt01122012 VALUES LESS THAN (TO_DATE('01-DEC-
2012', 'DD-MON-YYYY')),
PARTITION pt01022013 VALUES LESS THAN (TO_DATE('01-FEB-
2013', 'DD-MON-YYYY')),
PARTITION pt01042013 VALUES LESS THAN (TO_DATE('01-APR-
2013', 'DD-MON-YYYY')),
PARTITION pt01062013 VALUES LESS THAN (TO_DATE('01-JUN-
2013', 'DD-MON-YYYY')),
PARTITION pt01082013 VALUES LESS THAN (TO_DATE('01-AUG-
2013', 'DD-MON-YYYY'))
);

提前致谢...

Answer 1

首先,我想指出分区是Oracle中的一个高级主题,因此您可能希望在开始时手动运行所有DDL,直到您对运行DDL脚本有足够的信心.我还建议你永远不要运行在互联网上找到的脚本,而不必理解它并彻底测试它,尤其是DDL脚本.

现在就此而言,您可以查询*_TAB_PARTITIONS字典视图以检索分区边界:

SQL> SELECT partition_name, high_value
  2    FROM user_tab_partitions
  3   WHERE table_name = 'TEST_TABLE';

PARTITION_NAME  HIGH_VALUE
--------------- --------------------------------------------------------
PT01122012      TO_DATE(' 2012-12-01 00:00:00', 'SYYYY-MM-DD HH24:MI:SS'
PT01022013      TO_DATE(' 2013-02-01 00:00:00', 'SYYYY-MM-DD HH24:MI:SS'
PT01042013      TO_DATE(' 2013-04-01 00:00:00', 'SYYYY-MM-DD HH24:MI:SS'
PT01062013      TO_DATE(' 2013-06-01 00:00:00', 'SYYYY-MM-DD HH24:MI:SS'
PT01082013      TO_DATE(' 2013-08-01 00:00:00', 'SYYYY-MM-DD HH24:MI:SS'

这个列的类型是LONG(=不推荐的LOB),所以我们几乎没有用SQL过滤的工具,我们必须使用PL/SQL.

SQL> BEGIN
  2     FOR cc IN (SELECT partition_name, high_value --
  3                  FROM user_tab_partitions
  4                 WHERE table_name = 'TEST_TABLE') LOOP
  5        EXECUTE IMMEDIATE
  6           'BEGIN
  7               IF sysdate >= ADD_MONTHS(' || cc.high_value || ', 2) THEN
  8                  EXECUTE IMMEDIATE
  9                     ''ALTER TABLE TEST_TABLE DROP PARTITION '
 10                     || cc.partition_name || '
 11                     '';
 12               END IF;
 13            END;';
 14     END LOOP;
 15  END;
 16  /

PL/SQL procedure successfully completed

SQL> SELECT partition_name, high_value
  2    FROM user_tab_partitions
  3   WHERE table_name = 'TEST_TABLE';

PARTITION_NAME  HIGH_VALUE
--------------- -----------------------------------------------------------
PT01022013      TO_DATE(' 2013-02-01 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 
PT01042013      TO_DATE(' 2013-04-01 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 
PT01062013      TO_DATE(' 2013-06-01 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 
PT01082013      TO_DATE(' 2013-08-01 00:00:00', 'SYYYY-MM-DD HH24:MI:SS',