Oracle分批提交DML
1.采用分批操作并不能提高执行速度，执行效率不如单条DML语句。
2.分批插入可以减少对undo空间的占用，但频繁的提交，可能会导致前面提交的undo空间被其他事务占用而可能导致ORA-0155错误。
3.若分批操作中间半截失败掉，会将你数据库置于一种未知的状态。（DELETE操作不会出现这种情况）
1、分批UPDATE
DROP TABLE T2;
CREATE TABLE T2 AS SELECT OBJECT_NAME FROM DBA_OBJECTS;
SELECT * FROM T2;
SELECT COUNT(*) FROM T2;
DECLARE
TYPE RIDARRAY IS TABLE OF ROWID;
TYPE VCARRAY IS TABLE OF T2.OBJECT_NAME%TYPE;
L_RIDS RIDARRAY;
L_NAMES VCARRAY;
CURSOR C IS
SELECT ROWID,
OBJECT_NAME
FROM T2;
BEGIN
OPEN C;
LOOP
FETCH C BULK COLLECT
INTO L_RIDS,
L_NAMES LIMIT 10;
FORALL I IN 1 .. L_RIDS.COUNT
UPDATE T2
SET OBJECT_NAME = LOWER(L_NAMES(I))
WHERE ROWID = L_RIDS(I);
COMMIT;
EXIT WHEN C%NOTFOUND;
END LOOP;
CLOSE C;
END;
/
2、分批DELETE
DROP TABLE T3;
CREATE TABLE T3 AS SELECT * FROM DBA_OBJECTS;
DECLARE
CURSOR MYCURSOR IS
SELECT ROWID FROM T3 ORDER BY ROWID; --按ROWID排序的CURSOR，删除条件是XXX=XXXX，根据实际情况修改
TYPE ROWID_TABLE_TYPE IS TABLE OF ROWID INDEX BY PLS_INTEGER;
V_ROWID ROWID_TABLE_TYPE;
BEGIN
OPEN MYCURSOR;
LOOP
FETCH MYCURSOR BULK COLLECT
INTO V_ROWID LIMIT 5000; --每次处理5000行，也就是每5000行一提交
EXIT WHEN V_ROWID.COUNT = 0;
FORALL I IN V_ROWID.FIRST .. V_ROWID.LAST
DELETE FROM T3 WHERE ROWID = V_ROWID(I);
COMMIT;
END LOOP;
CLOSE MYCURSOR;
END;
/
3、分批INSERT
将T_20160401的数据全部插入T_20160401_01表。
DECLARE
CURSOR MYCURSOR IS
SELECT ROWID FROM T_20160401 ORDER BY ROWID;
TYPE ROWID_TABLE_TYPE IS TABLE OF ROWID INDEX BY PLS_INTEGER ;
V_ROWID ROWID_TABLE_TYPE;
V_COUNT NUMBER := 0;
V_START DATE;
V_END DATE;
BEGIN
SELECT SYSDATE INTO V_START FROM DUAL;
OPEN MYCURSOR;
LOOP
FETCH MYCURSOR BULK COLLECT
INTO V_ROWID LIMIT 50000;
EXIT WHEN V_ROWID.COUNT = 0;
FORALL I IN V_ROWID.FIRST .. V_ROWID.LAST
INSERT INTO T_20160401_01
SELECT * FROM T_20160401 T WHERE T.ROWID=V_ROWID(I);
V_COUNT:=V_COUNT+TO_CHAR(SQL%ROWCOUNT);
COMMIT;
END LOOP;
CLOSE MYCURSOR;
SELECT SYSDATE INTO V_END FROM DUAL;
DBMS_OUTPUT.PUT_LINE('START: ' || V_START);
DBMS_OUTPUT.PUT_LINE('INSERT: ' || V_COUNT);
DBMS_OUTPUT.PUT_LINE('END: ' || V_END);
COMMIT;
END;
/
DECLARE
CURSOR MYCURSOR IS
SELECT * FROM T_20160401 ORDER BY ROWID;
TYPE ROWID_TABLE_TYPE IS TABLE OF T_20160401%ROWTYPE;
V_ROWID ROWID_TABLE_TYPE;
BEGIN
OPEN MYCURSOR;
LOOP
FETCH MYCURSOR BULK COLLECT
INTO V_ROWID LIMIT 50000;
EXIT WHEN V_ROWID.COUNT = 0;
FORALL I IN V_ROWID.FIRST .. V_ROWID.LAST
INSERT INTO T_20160401_01 VALUES V_ROWID(I);
COMMIT;
END LOOP;
CLOSE MYCURSOR;
END;
/
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...............................................................................................................................● 本文作者：小麦苗，只专注于数据库的技术，更注重技术的运用
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