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使用DBMS_STATS.restore 恢复统计信息

2014-06-30 22:16 429 查看

我们可以恢复之前的统计信息，生成原本的执行计划

1 恢复之前的统计信息

SQL> BEGIN
2  DBMS_STATS.restore_table_stats(ownname => 'DAO',tabname => 'TEST_STATS',as_of_timestamp => '27-JUN-14 05.40.33.314757 PM +08:00');
3  END ;
4  /
PL/SQL procedure successfully completed.

2 查看执行计划

SQL> select  count(*) from  test_stats ;
COUNT(*)
----------
75675

Execution Plan
----------------------------------------------------------
Plan hash value: 2395052010

------------------------------------------------------------------------------
| Id  | Operation             | Name         | Rows  | Cost (%CPU)| Time     |
------------------------------------------------------------------------------
|   0 | SELECT STATEMENT      |              |     1 |    44   (0)| 00:00:01 |
|   1 |  SORT AGGREGATE       |              |     1 |            |          |
|   2 |   INDEX FAST FULL SCAN| DAO_STATS_PK | 75675 |    44   (0)| 00:00:01 |
------------------------------------------------------------------------------

Statistics
----------------------------------------------------------
0  recursive calls
0  db block gets
1081  consistent gets
0  physical reads
0  redo size
528  bytes sent via SQL*Net to client
523  bytes received via SQL*Net from client
2  SQL*Net roundtrips to/from client
0  sorts (memory)
0  sorts (disk)
1  rows processed

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