块的延迟清洗处理一则

                                                块的延迟清洗处理一则

    数据无法启动，报4194错误.通过undo_management=manual处理，然后再增加一个新的undo
tablespace,原有的undo1文件损坏

  打开数据库时报
ORA-01157: cannot identify/lock data file 5 - see DBWR trace file
ORA-01110: data file 5: '/u01/app/oracle/oradata/t/undo01.dbf'

SQL>  alter database datafile 5 offline for drop;

Database altered.

删除文件，数据顺利打开,在查询表时报无法锁定的错误

SQL> select count(*) from frank.t1;
select count(*) from frank.t1
                           *
ERROR at line 1:
ORA-00376: file 5 cannot be read at this time
ORA-01110: data file 5: '/u01/app/oracle/oradata/t/undo01.dbf'

看来还是没有清理干净，由于在这个表上的数据块的信息有对应在原来损坏的undo1上
在做select时，需要进行块清洗，但是对应的undo文件已经被删除了，导致无法去读
取.
  
直接删除表空间报错

SQL> drop tablespace undo2;
drop tablespace undo2
*
ERROR at line 1:
ORA-01548: active rollback segment '_SYSSMU11_1387200382$' found, terminate
dropping tablespace

看来只能通过_offline_rollback_segments,把该表空间所有的undo segment进行离线了.

SQL> alter system  set "_offline_rollback_segments"='_SYSSMU12_1387200382$','_SYSSMU13_1387200382$',
  2  '_SYSSMU14_1387200382$','_SYSSMU14_1387200382$','_SYSSMU15_1387200382$','_SYSSMU17_1387200382$','_SYSSMU18_1387200382$',
  3  '_SYSSMU19_1387200382$','_SYSSMU20_1387200382$','_SYSSMU16_1387200382$' scope=spfile;

System altered.

SQL> drop tablespace undo2;

Tablespace dropped.

SQL> select count(*) from frank.t1;

  COUNT(*)
----------
     68691

  查询成功.