Move 命令对索引的影响

前几天想起使用move命令，消除表碎片的事情。索引会不会失效。想了想应该会失效。

通过例子测试，使用move后，所以会失效，需要rebuild

测试如下：

创建一个测试表，并插入数据

SYS@test>create table bb_t1 tablespace bb as select * from dba_objects;

Table created.

SYS@test>select count(*) from bb_t1;

  COUNT(*)
----------
     87211
	 
SYS@test>insert into bb_t1 select * from bb_t1;

174422 rows created.

SYS@test>/

348844 rows created.

SYS@test>/

697688 rows created.

SYS@test>/

1395376 rows created.

SYS@test>/

2790752 rows created.

SYS@test>commit;

创建索引 

create index bb.idx_bb_t1 on bb_t1(object_id) tablespace bb;

--
SYS@test>select index_name, tablespace_name ,status ,visibility from dba_indexes where  table_name='BB_T1';

INDEX_NAME		       TABLESPACE_NAME		      STATUS   VISIBILIT
------------------------------ ------------------------------ -------- ---------
IDX_BB_T1		       BB			      VALID    VISIBLE

SYS@test>

进行movement

SYS@test>alter table bb_t1 enable row movement;

Table altered.

SYS@test>

SYS@test>alter table bb_t1 move;    

Table altered.

SYS@test>

查看索引状态

SYS@test>select index_name, tablespace_name ,status ,visibility from dba_indexes where  table_name='BB_T1';

INDEX_NAME		       TABLESPACE_NAME		      STATUS   VISIBILIT
------------------------------ ------------------------------ -------- ---------
IDX_BB_T1		       BB			      UNUSABLE VISIBLE

rebuild索引

SYS@test>alter index bb.idx_bb_t1 rebuild ;

Index altered.

再次查看索引状态

SYS@test>select index_name, tablespace_name ,status ,visibility from dba_indexes where  table_name='BB_T1';

INDEX_NAME		       TABLESPACE_NAME		      STATUS   VISIBILIT
------------------------------ ------------------------------ -------- ---------
IDX_BB_T1		       BB			      VALID    VISIBLE

SYS@test>

测试shrink。shrink完毕后，索引不会失效。

SYS@test>alter table bb_t1 shrink space cascade;

Table altered.

SYS@test>select index_name, tablespace_name ,status ,visibility from dba_indexes where  table_name='BB_T1';

INDEX_NAME		       TABLESPACE_NAME		      STATUS   VISIBILIT
------------------------------ ------------------------------ -------- ---------
IDX_BB_T1		       BB			      VALID    VISIBLE

SYS@test>

关闭movement

SYS@test>alter table bb_t1 disable row movement;

Table altered.

SYS@test>select row_movement from dba_tables where table_name='BB_T1'
  2  ;

ROW_MOVE
--------
DISABLED

SYS@test>

结论：使用move命令整理碎片，需要rebuild 索引，

使用shrink命令整理碎片，不需要rebuild索引 

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