工：闪回表实验

1.结构测试表flb_test，数据不小于10000行；

table flb_test(id number,dd date);

Table created.

  2  for i in 1..10000

  3  loop

  4  insert into flb_test values (i,sysdate+i);

  5  end loop;

  6  end;

  7  /

PL/SQL procedure successfully completed.

exec dbms_stats.gather_table_stats('TEST_USER1','FLB_TEST');

 --收集统计信息

2.查询当前时间与scn号；

to_char(sysdate,'yyyy-mm-dd hh24:mi:ss') from dual;

TO_CHAR(SYSDATE,'YY

-------------------

2014-10-13 19:23:29

dbms_flashback.get_system_change_number from dual;

GET_SYSTEM_CHANGE_NUMBER

------------------------

                 1144357

3.查看该測试表block数目及大小M。

SEGMENT_NAME,BYTES/1024/1024 size_m, BLOCKS from user_segments   

  2  where SEGMENT_NAME='FLB_TEST';

SEGMENT_NAME        SIZE_M     BLOCKS

--------------- ---------- ----------

FLB_TEST               .25         32

4.在这张表的第一和第二列上，创建一个复合索引ind_flb;

index ind_flb on flb_test(id,dd);

Index created.

5.查看该索引的叶子块的数目以及层数；

INDEX_NAME,STATUS ,BLEVEL,LEAF_BLOCKS from dba_indexes 

  2  where index_name ='IND_FLB';

INDEX_NAME                     STATUS       BLEVEL LEAF_BLOCKS

------------------------------ -------- ---------- -----------

IND_FLB                        VALID             1          33

   --平衡树：  高度=层数+1

SEGMENT_NAME,BYTES/1024/1024 size_m, BLOCKS from user_segments

  2  where SEGMENT_NAME='FLB_TEST';

SEGMENT_NAME        SIZE_M     BLOCKS

--------------- ---------- ----------

FLB_TEST               .25         32

6.删除測试表中一半的记录数并提交；

from flb_test where id<=5000;

5000 rows deleted.

;

Commit complete.

count(*) from flb_test;

  COUNT(*)

----------

      5000

dbms_stats.gather_table_stats('TEST_USER1','FLB_TEST');

PL/SQL procedure successfully completed.

dbms_stats.gather_index_stats('TEST_USER1','IND_FLB');

PL/SQL procedure successfully completed.

    --收集表和索引的统计信息

7.闪回fls_test到第二步查询到的时间点；

table_name ,row_movement from user_tables;

TABLE_NAME                     ROW_MOVE

------------------------------ --------

SALARY                         ENABLED

SYS_TEMP_FBT                   DISABLED

FLB_TEST                       DISABLED

EMP                            DISABLED

table flb_test enable row movement;

Table altered.

table_name ,row_movement from user_tables;

TABLE_NAME                     ROW_MOVE

------------------------------ --------

EMP                            DISABLED

FLB_TEST                       ENABLED

SYS_TEMP_FBT                   DISABLED

SALARY                         ENABLED

table flb_test to timestamp to_timestamp('2014-10-13 19:23:29','yyyy-mm-dd hh24:mi:ss');

Flashback complete.

dbms_stats.gather_table_stats('TEST_USER1','FLB_TEST');

PL/SQL procedure successfully completed.

dbms_stats.gather_index_stats('TEST_USER1','IND_FLB');

PL/SQL procedure successfully completed.

    --收集表和索引的统计信息

    --Oracle仅仅是闪回表，全部的东西都原样保留，应又一次收集统计信息

8.查看闪回结果，以及索引状态；

count(*) from flb_test;

  COUNT(*)

----------

     10000

INDEX_NAME,STATUS ,BLEVEL,LEAF_BLOCKS from dba_indexes

  2  where index_name ='IND_FLB';

INDEX_NAME                     STATUS       BLEVEL LEAF_BLOCKS

------------------------------ -------- ---------- -----------

IND_FLB                        VALID             1          33

 

 

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