作业：闪回表实验
1.构造测试表flb_test，数据不小于10000行；
[email protected]>create table flb_test(id number,dd date);
Table created.
[email protected]>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；
[email protected]>select to_char(sysdate,‘yyyy-mm-dd hh24:mi:ss‘) from dual;
TO_CHAR(SYSDATE,‘YY
-------------------
2014-10-13 19:23:29
[email protected]>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；
[email protected]>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;
[email protected]>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；
[email protected]>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
[email protected]>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；
[email protected]>delete from flb_test where id<=5000;
5000 rows deleted.
[email protected]>commit;
Commit complete.
[email protected]>select count(*) from flb_test;
COUNT(*)
----------
5000
[email protected]>exec dbms_stats.gather_table_stats(‘TEST_USER1‘,‘FLB_TEST‘);
PL/SQL procedure successfully completed.
[email protected]>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；
[email protected]>select table_name ,row_movement from user_tables;
TABLE_NAME ROW_MOVE
------------------------------ --------
SALARY ENABLED
SYS_TEMP_FBT DISABLED
FLB_TEST DISABLED
EMP DISABLED
[email protected]>alter table flb_test enable row movement;
Table altered.
[email protected]>select table_name ,row_movement from user_tables;
TABLE_NAME ROW_MOVE
------------------------------ --------
EMP DISABLED
FLB_TEST ENABLED
SYS_TEMP_FBT DISABLED
SALARY ENABLED
TEST[email protected]>flashback table flb_test to timestamp to_timestamp(‘2014-10-13 19:23:29‘,‘yyyy-mm-dd hh24:mi:ss‘);
Flashback complete.
[email protected]>exec dbms_stats.gather_table_stats(‘TEST_USER1‘,‘FLB_TEST‘);
PL/SQL procedure successfully completed.
[email protected]>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；
[email protected]>select count(*) from flb_test;
COUNT(*)
----------
10000
[email protected]>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