用BULK COLLECT 減小LOOP的開銷(1)
DECLARE
-- ALL_ROWS NUMBER(10);
TYPE LAST_NAME_TAB IS RECORD(
sorder_no VARCHAR2(30),
mem_id VARCHAR2(50),
createddt DatE,
usertype integer,
delegate_id VARCHAR2(50));
LAST_NAME_ARR LAST_NAME_TAB;
TYPE T_SORDER IS TABLE OF LAST_NAME_TAB;
VAR_EDM T_SORDER := T_SORDER();
CURSOR P_CUR IS(
SELECT DISTINCT decode(a.order_type,
'ReturnOrder',
a.ref_order_no,
sorder_no) sorder_no,
mem_id,
createddt,
b.usertype,
a.delegate_id
FROM user);
-- ALL_ROWS NUMBER(10);
TYPE LAST_NAME_TAB IS RECORD(
sorder_no VARCHAR2(30),
mem_id VARCHAR2(50),
createddt DatE,
usertype integer,
delegate_id VARCHAR2(50));
LAST_NAME_ARR LAST_NAME_TAB;
TYPE T_SORDER IS TABLE OF LAST_NAME_TAB;
VAR_EDM T_SORDER := T_SORDER();
CURSOR P_CUR IS(
SELECT DISTINCT decode(a.order_type,
'ReturnOrder',
a.ref_order_no,
sorder_no) sorder_no,
mem_id,
createddt,
b.usertype,
a.delegate_id
FROM user);
BEGIN
OPEN p_cur;
FETCH P_CUR BULK COLLECT
INTO VAR_EDM;
OPEN p_cur;
FETCH P_CUR BULK COLLECT
INTO VAR_EDM;
FOR I IN 1 .. VAR_EDM.COUNT() LOOP
/*INSERT \* +APPEND *\
INTO PTL_SYSTEM_MESSAGE
(USERID, CREATEDBY, MAILADDRESS, TEMPLATE_ID)
VALUES
(VAR_EDM(I).USERID, VAR_EDM(I).CREATEDBY, VAR_EDM(I).MAILADDRESS, VAR_EDM(I)
.TEMPLATE_ID);
COMMIT;*/
DBMS_OUTPUT.PUT_LINE(VAR_EDM(I).mem_id || '---' || VAR_EDM(I)
.CREATEDDT || '---' || VAR_EDM(I)
.usertype || '---' || VAR_EDM(I)
.delegate_id || '---' || VAR_EDM(I).SORDER_NO);
END LOOP;
END;
/*INSERT \* +APPEND *\
INTO PTL_SYSTEM_MESSAGE
(USERID, CREATEDBY, MAILADDRESS, TEMPLATE_ID)
VALUES
(VAR_EDM(I).USERID, VAR_EDM(I).CREATEDBY, VAR_EDM(I).MAILADDRESS, VAR_EDM(I)
.TEMPLATE_ID);
COMMIT;*/
DBMS_OUTPUT.PUT_LINE(VAR_EDM(I).mem_id || '---' || VAR_EDM(I)
.CREATEDDT || '---' || VAR_EDM(I)
.usertype || '---' || VAR_EDM(I)
.delegate_id || '---' || VAR_EDM(I).SORDER_NO);
END LOOP;
END;
-------------------------------------------------------------------------------------------------------------
透過bulk collect減少loop處理的開銷
採用bulk collect可以將查詢結果一次性地載入到collections中。
而不是透過cursor一條一條地處理。
可以在select into,fetch into,returning into語句使用bulk collect。
注意在使用bulk collect時,所有的into變數都必須是collections.
舉幾個簡單的例子:
--在select into語句中使用bulk collect
DECLARE
TYPE SalList IS TABLE OF emp.sal%TYPE;
sals SalList;
BEGIN
-- Limit the number of rows to 100.
SELECT sal BULK COLLECT INTO sals FROM emp
WHERE ROWNUM <= 100;
-- Retrieve 10% (approximately) of the rows in the table.
SELECT sal BULK COLLECT INTO sals FROM emp SAMPLE 10;
TYPE SalList IS TABLE OF emp.sal%TYPE;
sals SalList;
BEGIN
-- Limit the number of rows to 100.
SELECT sal BULK COLLECT INTO sals FROM emp
WHERE ROWNUM <= 100;
-- Retrieve 10% (approximately) of the rows in the table.
SELECT sal BULK COLLECT INTO sals FROM emp SAMPLE 10;
END;
/
/
--在fetch into中使用bulk collect
DECLARE
TYPE DeptRecTab IS TABLE OF dept%ROWTYPE;
dept_recs DeptRecTab;
CURSOR c1 IS
SELECT deptno, dname, loc FROM dept WHERE deptno > 10;
BEGIN
OPEN c1;
FETCH c1 BULK COLLECT INTO dept_recs;
END;
/
TYPE DeptRecTab IS TABLE OF dept%ROWTYPE;
dept_recs DeptRecTab;
CURSOR c1 IS
SELECT deptno, dname, loc FROM dept WHERE deptno > 10;
BEGIN
OPEN c1;
FETCH c1 BULK COLLECT INTO dept_recs;
END;
/
--在returning into中使用bulk collect
CREATE TABLE emp2 AS SELECT * FROM employees;
DECLARE
TYPE NumList IS TABLE OF employees.employee_id%TYPE;
enums NumList;
TYPE NameList IS TABLE OF employees.last_name%TYPE;
names NameList;
BEGIN
DELETE FROM emp2 WHERE department_id = 30
RETURNING employee_id, last_name BULK COLLECT INTO enums, names;
dbms_output.put_line('Deleted ' || SQL%ROWCOUNT || ' rows:');
FOR i IN enums.FIRST .. enums.LAST
LOOP
dbms_output.put_line('Employee #' || enums(i) || ': ' || names(i));
END LOOP;
END;
/
DROP TABLE emp2;
DECLARE
TYPE NumList IS TABLE OF employees.employee_id%TYPE;
enums NumList;
TYPE NameList IS TABLE OF employees.last_name%TYPE;
names NameList;
BEGIN
DELETE FROM emp2 WHERE department_id = 30
RETURNING employee_id, last_name BULK COLLECT INTO enums, names;
dbms_output.put_line('Deleted ' || SQL%ROWCOUNT || ' rows:');
FOR i IN enums.FIRST .. enums.LAST
LOOP
dbms_output.put_line('Employee #' || enums(i) || ': ' || names(i));
END LOOP;
END;
/
DROP TABLE emp2;
來自 “ ITPUB部落格 ” ,連結:http://blog.itpub.net/22392018/viewspace-705263/,如需轉載,請註明出處,否則將追究法律責任。
相關文章
- 使用oracle bulk collect 提高select FETCH LOOP的速度OracleOOP
- Oracle 的 bulk collect用法Oracle
- pl/sql中bulk collect的用法SQL
- 【PL/SQL】初試 bulk collectSQL
- BULK COLLECT FAILS WITH ORA-04030AI
- 使用BULK COLLECT+FORALL加速批量提交
- APPEND,bulk collect,正常插入比較APP
- 使用Bulk Collect提高Oracle查詢效率Oracle
- 多行資料的批處理之bulk collect
- PL/SQL LOB和檔案操作,bulk collectSQL
- 使用bulk collect實現cursor 批量fetch!
- 使用Forall 與bulk collect的快速複製表資料
- Oracle中巧用bulk collect實現cursor批次fetchOracle
- 遊標+bulk collect into limit的不同方法查詢資料MIT
- Oracle資料庫的BULK COLLECT用法之批量增刪改<轉>Oracle資料庫
- [20180110]Oracle Bulk Collect and LimitOracleMIT
- oracle中bulk collect into用法 (批次效率提取遊標資料)Oracle
- 一次遷移思考的記錄--bulk_collect的limit用法MIT
- oracle10g_plsql_rercursor_type_table of_小引例_bulk collect intoOracleSQL
- [20180111]Oracle Bulk Collect and Limit2OracleMIT
- 轉摘plsql高階程式設計_table_array_for all_bulk collect into_fetchSQL程式設計
- bulk_collect結合dbms_application_info監控資料處理進度APP
- 抵銷、轉銷、衝回、衝減、沖銷的區別
- 用 Laravel Collect 收藏文章Laravel
- swiper.js loop 小坑JSOOP
- Android開發如何有效減小APK的體積AndroidAPK
- 減小APK大小APK
- 安卓開發的小技巧(1)安卓
- 減小Delphi的Exe檔案大小
- 一個更好用的.NET Core程式瘦身器,減小程式尺寸到1/3
- Elasticsearch的Bulk API使用ElasticsearchAPI
- vue i18n-collect工具開發Vue
- 字串池化,減少1/3記憶體佔用字串記憶體
- QT錯誤之——collect2:ld returned 1 exit statusQT
- 分析:1千萬應用下載量的營銷技巧
- Go 語言中的 collect 使用Go
- 減小SQL SERVER的日誌檔案SQLServer
- 應用市場競爭加劇 遊戲營銷成本有增無減遊戲