作业：闪回表实验

1.构造测试表flb_test，数据不小于10000行；

TEST_USER1@PROD>create table flb_test(id number,dd date);

Table created.

TEST_USER1@PROD>begin
  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；

TEST_USER1@PROD>select to_char(sysdate,‘yyyy-mm-dd hh24:mi:ss‘) from dual;

TO_CHAR(SYSDATE,‘YY
-------------------
2014-10-13 19:23:29

TEST_USER1@PROD>select dbms_flashback.get_system_change_number from dual;

GET_SYSTEM_CHANGE_NUMBER
------------------------
                 1144357

3.查看该测试表block数目及大小M；

TEST_USER1@PROD>select 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;

TEST_USER1@PROD>create 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；

TEST_USER1@PROD>select 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

TEST_USER1@PROD>select 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.删除测试表中一半的记录数并提交；

TEST_USER1@PROD>delete from flb_test where id<=5000;

5000 rows deleted.

TEST_USER1@PROD>commit;

Commit complete.

TEST_USER1@PROD>select count(*) from flb_test;

  COUNT(*)
----------
      5000

TEST_USER1@PROD>exec dbms_stats.gather_table_stats(‘TEST_USER1‘,‘FLB_TEST‘);

PL/SQL procedure successfully completed.

TEST_USER1@PROD>exec 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；

TEST_USER1@PROD>select table_name ,row_movement from user_tables;

TABLE_NAME                     ROW_MOVE
------------------------------ --------
SALARY                         ENABLED
SYS_TEMP_FBT                   DISABLED
FLB_TEST                       DISABLED
EMP                            DISABLED

TEST_USER1@PROD>alter table flb_test enable row movement;

Table altered.

TEST_USER1@PROD>select table_name ,row_movement from user_tables;

TABLE_NAME                     ROW_MOVE
------------------------------ --------
EMP                            DISABLED
FLB_TEST                       ENABLED
SYS_TEMP_FBT                   DISABLED
SALARY                         ENABLED

TEST_USER1@PROD>flashback table flb_test to timestamp to_timestamp(‘2014-10-13 19:23:29‘,‘yyyy-mm-dd hh24:mi:ss‘);

Flashback complete.

TEST_USER1@PROD>exec dbms_stats.gather_table_stats(‘TEST_USER1‘,‘FLB_TEST‘);

PL/SQL procedure successfully completed.

TEST_USER1@PROD>exec 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只是闪回表，所有的东西都原样保留，应重新收集统计信息

8.查看闪回结果，以及索引状态；

TEST_USER1@PROD>select count(*) from flb_test;

  COUNT(*)
----------
     10000

TEST_USER1@PROD>select 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

Oracle 闪回表实验