使用DBMS_STATS.restore 恢复统计信息

我们可以恢复之前的统计信息，生成原本的执行计划

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.

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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