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bulk批量刪除數(shù)據(jù)
需要在一個(gè)1億行的大表中,刪除1千萬(wàn)行數(shù)據(jù)
需求是在對(duì)數(shù)據(jù)庫(kù)其他應(yīng)用影響最小的情況下,以最快的速度完成
如果業(yè)務(wù)無法停止的話,可以參考下列思路:
根據(jù)ROWID分片、再利用Rowid排序、批量處理、回表刪除
在業(yè)務(wù)無法停止的時(shí)候,選擇這種方式,的確是最好的
一般可以控制在每一萬(wàn)行以內(nèi)提交一次,不會(huì)對(duì)回滾段造成太大壓力
我在做大DML時(shí),通常選擇一兩千行一提交
選擇業(yè)務(wù)低峰時(shí)做,對(duì)應(yīng)用也不至于有太大影響
drop table t_emp purge;
create table t_emp as select * from emp;
insert into t_emp select * from t_emp;
insert into t_emp select * from t_emp;
insert into t_emp select * from t_emp;
insert into t_emp select * from t_emp;
insert into t_emp select * from t_emp;
insert into t_emp select * from t_emp;
insert into t_emp select * from t_emp;
insert into t_emp select * from t_emp;
insert into t_emp select * from t_emp;
insert into t_emp select * from t_emp;
insert into t_emp select * from t_emp;
commit;
declare
cursor c_rowid is
select rowid from t_emp where deptno = 30 order by rowid; --data need to be deleted
type type_rowid is table of rowid index by pls_integer;
v_tab_rowid type_rowid;
v_num number := 0;
begin
open c_rowid;
loop
fetch c_rowid bulk collect
into v_tab_rowid limit 50;
--exit when c_rowid%notfound;
forall i in v_tab_rowid.first .. v_tab_rowid.last
delete from t_emp where rowid = v_tab_rowid(i);
commit;
v_num := v_num + v_tab_rowid.count;
exit when c_rowid%notfound;
endloop;
close c_rowid;
dbms_output.put_line(to_char(sysdate, 'yyyy-mm-dd:') || 'delete rows '||
to_char(v_num));
end;
/
declare
cursor c_rowid is
select rowid from t_emp where deptno = 30 order by rowid; --data need tobe deleted
type type_rowid is table of rowid index by pls_integer;
v_tab_rowid type_rowid;
v_num number := 0;
begin
open c_rowid;
loop
fetch c_rowid bulk collect
into v_tab_rowid limit 50;
exit when v_tab_rowid.count=0;
forall i in v_tab_rowid.first .. v_tab_rowid.last
delete from t_emp where rowid = v_tab_rowid(i);
commit;
v_num := v_num + v_tab_rowid.count;
endloop;
close c_rowid;
dbms_output.put_line(to_char(sysdate, 'yyyy-mm-dd:') || 'delete rows '||
to_char(v_num));
end;
/
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