Oracle 分区表进行shrink操作

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【背景】公司业务系统的数据增长很快，需要进行定期进行归档，其中有些数据用分区表进行存储，归档完之后释放了大量的空间，之前已经有文档介绍普通表进行shrink操作的步骤，本文档记录对Oracle分区表和复合分区表进行shrink的操作；

测试环境的搭建】
Oracle数据库版本：11.2.0.3
分区表的创建

CREATE TABLE SCOTT.PTABLE

(
  GG1DM VARCHAR2(9 BYTE),
  SL NUMBER(18,4) ,
  DJBH VARCHAR2(20 BYTE)
  )
NOCOMPRESS
PARTITION BY LIST (GG1DM)
SUBPARTITION BY range (SL)
(
  PARTITION PTABLE_P1 VALUES ('07')
  (
    SUBPARTITION PTABLE1_SUB1 VALUES less than (50) ,
    SUBPARTITION PTABLE1_SUB2 VALUES less than (100),
    SUBPARTITION PTABLE1_SUB3 VALUES less than (150),
    SUBPARTITION PTABLE1_SUB4 VALUES less than (250)
    )
  ,
  PARTITION PTABLE_P2 VALUES ('08')
  (SUBPARTITION PTABLE2_SUB1 VALUES less than (50) ,
    SUBPARTITION PTABLE2_SUB2 VALUES less than (100),
    SUBPARTITION PTABLE2_SUB3 VALUES less than (150),
    SUBPARTITION PTABLE2_SUB4 VALUES less than (250)
  ),
  PARTITION PTABLE_P3 VALUES ('09')
  ( SUBPARTITION PTABLE3_SUB1 VALUES less than (50) ,
    SUBPARTITION PTABLE3_SUB2 VALUES less than (100),
    SUBPARTITION PTABLE3_SUB3 VALUES less than (150),
    SUBPARTITION PTABLE3_SUB4 VALUES less than (250)
  )
  )

插入数据后需要更新统计信息：

analyze table PTABLE compute statistics;

分区表的查询
select t3.table_name, t3.partition_name,t3.high_value,t3.num_rows,t3.blocks,t3.empty_blocks,t3.last_analyzed
  from dba_tab_partitions t3 where t3.table_name='PTABLE' order by t3.num_rows desc

子分区表信息的查询

select t3.partition_name,t3.subpartition_name,t3.high_value,t3.num_rows,t3.blocks,t3.empty_blocks,t3.last_analyzed
    from dba_tab_subpartitions t3 where t3.table_name='PTABLE' order by t3.num_rows desc

【进行删除数据的测试】

DELETE FROM SCOTT.PTABLE WHERE GG1DM='07' AND SL<=50 删除PTABLE1_SUB1里面的数据
analyze table PTABLE compute statistics;  进行统计信息的更新；
然后查看此时子分区的高水位线情况

select t3.partition_name,t3.subpartition_name,t3.high_value,t3.num_rows,t3.blocks,t3.empty_blocks,t3.last_analyzed

    from dba_tab_subpartitions t3 where t3.table_name='PTABLE' order by t3.num_rows desc

当前PTABLE_P1表的数据是0，但是HMW线还是没有变；

【进行高水位线的回收】

alter table PTABLE enable row movement; #开启行迁移

alter table PTABLE MODIFY SUBPARTITION PTABLE1_SUB1 shrink space; #进行子分区空间的收缩
analyze table PTABLE compute statistics; #再次更新统计信息
select t3.partition_name,t3.subpartition_name,t3.high_value,t3.num_rows,t3.blocks,t3.empty_blocks,t3.last_analyzed
    from dba_tab_subpartitions t3 where t3.table_name='PTABLE' order by t3.num_rows desc; #查看子分区的情况

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