Oracle 10g批量绑定forall bulk collect

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批量绑定可以通过减少在PL/SQL和SQL引擎之间的上下文切换(context switches )以此提高性能。

批量绑定（Bulk binds）主要包括：

(1) Input collections, use the FORALL statement，用来改善DML（INSERT、UPDATE和DELETE) 操作的性能。

(2) Output collections, use BULK COLLECT clause，用来提高查询（SELECT）的性能。

Oracle 10g开始forall语句可以使用三种方式：

◆ in low..up

◆ in indices of collection 取得集合元素下标的值。

◆ in values of collection 取得集合元素的值。

forall语句还可以使用部分集合元素。

sql%bulk_rowcount(i)表示forall语句第i元素所作用的行数。

--drop table blktest;
--CREATE TABLE blktest (num NUMBER(20), name varchar2(50));
--CREATE OR REPLACE PROCEDURE p_bulktest　IS
DECLARE
TYPE type_num IS TABLE OF NUMBER INDEX BY BINARY_INTEGER;
TYPE type_name IS TABLE OF VARCHAR2(50) INDEX BY BINARY_INTEGER;
tab_num type_num;
tab_name type_name;
t1 NUMBER;
t2 NUMBER;
t3 NUMBER;

BEGIN
FOR i IN 1 .. 500000 LOOP
tab_num(i) := i;
tab_name(i) := 'name: ' || to_char(i);
END LOOP;

SELECT dbms_utility.get_time 　　　
INTO t1 　　　
FROM dual;

FOR i IN 1 .. 500000 LOOP
INSERT INTO blktest 　　　　　　
VALUES
(tab_num(i), tab_name(i));
END LOOP;

SELECT dbms_utility.get_time 　　　
INTO t2 　　　
FROM dual;

FORALL i IN 1 .. 500000
INSERT INTO blktest 　　　　　　
VALUES
(tab_num(i), tab_name(i));

SELECT dbms_utility.get_time 　　　
INTO t3 　　　
FROM dual;

dbms_output.put_line('Execution Time(S)');
dbms_output.put_line('-------------------');
dbms_output.put_line('FOR loop: ' 
|| to_char((t2 - t1) / 100));
dbms_output.put_line('FORALL:　 ' 
|| to_char((t3 - t2) / 100));

END;
/*
Execution Time(S)
-------------------
FOR loop: 32.78
FORALL:　 2.64
*/

/*
bulk collect 语句：
用于取得批量数据，只适用于select into ,fetch into 及DML语句的返回子句
DECLARE
TYPE type_emp IS TABLE OF 
scott.emp%ROWTYPE INDEX BY BINARY_INTEGER;
tab_emp type_emp;

TYPE type_ename IS TABLE OF 
scott.emp.ename%TYPE INDEX BY BINARY_INTEGER;
tab_ename type_ename;
CURSOR c IS
SELECT *
FROM scott.emp;
BEGIN
SELECT * BULK COLLECT
INTO tab_emp
FROM scott.emp;
FOR i IN 1 .. tab_emp.COUNT LOOP
dbms_output.put_line(tab_emp(i).ename);
END LOOP;

dbms_output.new_line;
DELETE scott.emp RETURNING 
ename BULK COLLECT INTO tab_ename;
FOR i IN 1 .. tab_emp.COUNT LOOP
dbms_output.put_line(tab_emp(i).ename);
END LOOP;
ROLLBACK;

OPEN c;
FETCH c BULK COLLECT
INTO tab_emp;
dbms_output.new_line;
FOR i IN 1 .. tab_emp.COUNT LOOP
dbms_output.put_line(tab_emp(i).sal);
END LOOP;

END;
*/

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批量输入FORALL+批量输出BULK

DECLARE
--批量输入FORALL+批量输出BULK
TYPE type_num IS TABLE OF NUMBER;
tab_1 type_num;
tab_2 type_num;
BEGIN
tab_1 := type_num(1, 2, 3); 
FORALL i IN 1 .. tab_1.COUNT 
--EXECUTE IMMEDIATE 'update t2 set id2=id*2 
where id=:1 returning id2 into :2' 
--USING tab_1(i) RETURNING BULK COLLECT INTO tab_2;
update t2 set id2=id*2 where id=tab_1(i) 
returning id2 bulk collect into tab_2;
FOR i IN 1 .. tab_2.COUNT LOOP
dbms_output.put_line(tab_2(i));
END LOOP;
END; 

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