Bulk Binds對性能的提高

 當Oracle運作PL/SQL時會使用兩套引擎，所有procedural code由PL/SQL engine 完成，所有SQL由SQL engine處理。是以如果Oracle從一個collection中循環執行相同的DML操作，那麼為了避免兩套engine切換所消耗的系統資源，可以使用bulk binds來把所有的DML操作binding到一次操作中完成。這将極大提高PL/SQL的執行效率。

　　以下是簡單的測試，用兩種方式插入100000條資料，可以看到效率提高了7倍左右。

SQL> CREATE TABLE test1(

2 id NUMBER(10),

3 description VARCHAR2(50));

Table created

SQL> ALTER TABLE test1 ADD (

2 CONSTRAINT test1_pk PRIMARY KEY (id));

Table altered

SQL> SET TIMING ON;

SQL> DECLARE

2 TYPE id_type IS TABLE OF test1.id%TYPE;

3 TYPE description_type IS TABLE OF test1.description%TYPE;

4

5 t_id id_type := id_type();

6 t_description description_type := description_type();

7 BEGIN

8 FOR i IN 1 .. 100000 LOOP

9 t_id.extend;

10 t_description.extend;

11

12 t_id(t_id.last) := i;

13 t_description(t_description.last) := 'Description: ' || To_Char(i);

14 END LOOP;

15

16 FOR i IN t_id.first .. t_id.last LOOP

17 INSERT INTO test1 (id, description)

18 VALUES (t_id(i), t_description(i));

19 END LOOP;

20

21 COMMIT;

22 END;

23 /

PL/SQL procedure successfully completed

Executed in 141.233 seconds

SQL> truncate table test1;

Table truncated

Executed in 0.631 seconds

SQL>

16 FORALL i IN t_id.first .. t_id.last

19

20 COMMIT;

21 END;

22 /

Executed in 27.52 seconds

SQL> select count(*) from test1;

COUNT(*)

----------

100000

Executed in 0.04 seconds