在使用delete語句刪除數(shù)據(jù)時，數(shù)據(jù)庫是要做日志記錄的，以便將來可以恢復數(shù)據(jù)，可是我在刪除上百萬條數(shù)據(jù)時，十分緩慢甚至死機，請問有沒有什么好方法? 網(wǎng)友觀點一:create or replace PRocedure delete_table
is
i number(10);
begin
for x in (select * from emp where DEPTNO like 'a%')
loop
delete emp where emp.id = x.id
i:=i+1;
if i>1000 then
commit;
i:=0;
end if;
end loop;
exception
when others then
dbms_out.put_line(sqlcode);
rollback;
end delete_table;
網(wǎng)友觀點二:這個是我平常用來批量刪除數(shù)據(jù)，每500條數(shù)據(jù)提交一次。
DECLARE
CNT NUMBER(10):=0;
I NUMBER(10);
BEGIN
SELECT COUNT(*) INTO CNT FROM ep_arrearage_bak WHERE TO_CHAR(DF_DATE,'MM')='01';FOR I IN 1..TRUNC(CNT/500)+1 LOOP
DELETE FROM ep_arrearage_bak WHERE TO_CHAR(DF_DATE,'MM')='01' AND ROWNUM<=500;
COMMIT;
END LOOP;
END;
專家意見:幾個辦法: 1. 假如刪除的數(shù)據(jù)是大部分,建議使用樓上的方法把要保留的數(shù)據(jù)放在一個臨時表里,truncate table后再放回來 2. 也可以分段提交,樓上也提到了 3. 專門使用一個大回滾段 4. 假如確認將來不需要做恢復,改為非歸檔模式,刪除完改回來再做個備份. 專家給出的解決方案:有條件的分步刪除數(shù)據(jù)表中的記錄
--創(chuàng)建測試表
create table test as select * from dba_objects;Table created.
--創(chuàng)建刪除表的存儲過程
create or replace procedure deleteTab
--插入語句
SQL> insert into test select * from dba_objects;6374 rows created.SQL> /6374 rows created.SQL> /6374 rows created.SQL> commit;--創(chuàng)建刪除的存儲過程
create or replace procedure deleteTab
/**
** Usage: run the script to create the proc deleteTab
** in SQL*PLUS, type "exec deleteTab('Foo','ID>=1000000','3000');"
** to delete the records in the table "Foo", commit per 3000 records.
** Condition with default value '1=1' and default Commit batch is 10000.
**/
(
p_TableName in varchar2, -- The TableName which you want to delete from
p_Condition in varchar2 default '1=1', -- Delete condition, sUCh as "id>=100000"
p_Count in varchar2 default '10000' -- Commit after delete How many records
)
as
pragma autonomous_transaction;
n_delete number:=0;
begin
while 1=1 loop
EXECUTE IMMEDIATE
'delete from 'p_TableName' where 'p_Condition' and rownum <= :rn'
USING p_Count;
if SQL%NOTFOUND then
exit;
else
n_delete:=n_delete + SQL%ROWCOUNT;
end if;
commit;
end loop;
commit;
DBMS_OUTPUT.PUT_LINE('Finished!');
DBMS_OUTPUT.PUT_LINE('Totally 'to_char(n_delete)' records deleted!');
end;
/--執(zhí)行語句
SQL> exec deleteTab('TEST','object_id >0','10000')
你看看執(zhí)行結(jié)果我試驗過，效果還可以
