oracle对于大表利用rowid提升update性能

使用rowid能迅速的定位数据，从而提升update效率

1.在scott表中创建test表

SQL> create table test as select * from dba_audit_trail;

Table created.

SQL> set timing on;

SQL> select count(*) from test;

COUNT(*)

----------

2086439

Elapsed: 00:00:00.73

2. order by rowid 对块进行排序，减少块访问的次数

DECLARE

CURSOR CUR IS

SELECT ROWID AS ROW_ID FROM TEST ORDER BY ROWID;

V_COUNTER NUMBER;

BEGIN

V_COUNTER := 0;

FOR ROW IN CUR LOOP

UPDATE TEST SET USERNAME = 'ghsj_jcsj' WHERE ROWID = ROW.ROW_ID;

V_COUNTER := V_COUNTER + 1;

IF (V_COUNTER >= 1000) THEN

COMMIT;

V_COUNTER := 0;

END IF;

END LOOP;

COMMIT;

END;

PL/SQL procedure successfully completed.

Elapsed: 00:06:04.89

200多万条记录只花了6分多钟，效率还可以。

本文乃原创文章，请勿转载。如须转载请详细标明转载出处