当前位置 博文首页 > LuciferLiu_DBA:记一次大表delete删数据导致数据库异常
早上正在上班路上,群里客户说,有一张24G的大表,delete删了26小时还没有跑完,目前进程还在跑让帮忙处理下,停止当前进程,并保留对应条件的数据,多余数据删掉。
1.未开归档
2.UNDO表空间爆满
1.经过沟通,该表为测试数据表,目前没有在使用;于是打算rename该表,通过ctas的方式去将需要的数据捞出来,重建索引和相关约束。
2.存在一个问题:delete进程已经执行了26小时,如果kill进程,必然会导致undo回滚,回滚默认开启并行会导致数据库和系统负载很高,于是需要提前处理下,设置参数fast_start_parallel_rollback关掉UNDO并行。
--查看回滚参数设置,是否是默认并行
SQL> show parameter fast_start_parallel_rollback
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
fast_start_parallel_rollback string LOW
--LOW 代表 开启CPU*2并行
--设置spfile取消并行
SQL> alter system set fast_start_parallel_rollback=false;
System altered.
SELECT d.OWNER
,d.OBJECT_NAME
,d.OBJECT_TYPE
,d.status
FROM dba_objects d
WHERE d.status = 'INVALID'
AND d.owner = '**';
--查询SID, SERIAL#
select s.SQL_TEXT, se.SID, se.SERIAL#
from v$session se, v$sql s
where s.sql_id = se.SQL_ID
and username = '**'
and status = 'ACTIVE'
and s.SQL_TEXT like '%delete * from *****%';
--数据库级kill进程
alter system kill session '2953,31083';
报错
ERROR at line 1:
ORA-00031: session marked for kill
--系统级 kill进程
select spid, osuser, s.program
from v$session s,v$process p
where s.paddr=p.addr and s.sid=2953;
kill -9 105257
--查看等待事件
select inst_id,event,count(*)
from gv$session a
where a.status='ACTIVE'
and not (a.type = 'BACKGROUND' and a.state='WAITING' and a.wait_class='Idle')
group by inst_id,event
order by a.inst_id,count(*) desc;
---------------------------------------------------
1 wait for a undo record 61
1 resmgr:cpu quantum 29
1 enq: RO - fast object reuse 22
1 enq: CR - block range reuse ckpt 20
1 free buffer waits 17
--查看当前数据回滚情况
alter session set nls_date_format='yyyy-mm-dd hh24:mi:ss';
select usn,
state,
undoblockstotal "Total",
undoblocksdone "Done",
undoblockstotal - undoblocksdone "ToDo",
decode(cputime,
0,
'unknown',
sysdate + (((undoblockstotal - undoblocksdone) /
(undoblocksdone / cputime)) / 86400)) "Estimated time to complete"
from v$fast_start_transactions
where state = 'RECOVERING';
---------------------------------------------------
83 RECOVERING 9026713 455 9026258 26-4月 -21
rename table to table_20210410;
create table USER.TABLE
nologging
parallel 8
tablespace TBS
as select /*+parallel(TABLE,'8')*/ *
from USER.TABLE_20210410
where *** like '******%';
--取消并行
alter table USER.TABLE noparallel;
--开启logging
alter table USER.TABLE logging;
alter index USER.INDEX1 rename to INDEX1_20210410;
--重建索引
create index USER.INDEX1 on USER.TABLE (***) tablespace TBS parallel 8;
--取消并行
alter index USER.INDEX1 noparallel;
drop table USER.TABLE_20210410 cascade;
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