oracle並行原理詳解（下）

Statistics   統計資訊

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

197  recursive calls

185  db block gets

92  consistent gets

60  physical reads

37128  redo size                    37128 redo量

664  bytes sent via SQL*Net to client

571  bytes received via SQL*Net from client

4  SQL*Net roundtrips to/from client

3  sorts (memory)

0  sorts (disk)

10340  rows processed

LS@LEO> rollback;   復原

Rollback complete.

LS@LEO> insert /*+ append */ into leo_t5 select * from leo_t6;  直接載入

10340 rows created.

Statistics

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

111  recursive calls

180  db block gets

79  consistent gets

21  physical reads

36640  redo size                    36640 redo量

664  bytes sent via SQL*Net to client

585  bytes received via SQL*Net from client

4  SQL*Net roundtrips to/from client

2  sorts (memory)

0  sorts (disk)

10340  rows processed

小結：我們看到傳統載入和直接載入產生的redo量並沒有太大的差異，因為只要底層資料區塊發生變化，就會產生redo資訊，

不管傳統和直接都會修改資料區塊，用來恢複依據，所以並沒有太大的差異。

（10）直接載入和索引

LS@LEO> set autotrace trace stat;

LS@LEO> insert /*+ append */ into leo_t5 select * from leo_t6;   直接載入，但表上沒有索引

10340 rows created.

Statistics   統計資訊

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

111  recursive calls

175  db block gets

81  consistent gets

15  physical reads

36816  redo size              36816 redo量

664  bytes sent via SQL*Net to client

585  bytes received via SQL*Net from client

4  SQL*Net roundtrips to/from client

2  sorts (memory)

0  sorts (disk)

10340  rows processed

LS@LEO> create index leo_t5_index on leo_t5(object_id);     給表建立索引

Index created.

LS@LEO> rollback;  復原

Rollback complete.

LS@LEO> insert /*+ append */ into leo_t5 select * from leo_t6;  直接載入，但表上有索引

10340 rows created.

Statistics   統計資訊

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

120  recursive calls

193  db block gets

85  consistent gets

22  physical reads

37344  redo size              37344 redo量

664  bytes sent via SQL*Net to client

585  bytes received via SQL*Net from client

4  SQL*Net roundtrips to/from client

3  sorts (memory)