提示：Oracle的隐含参数只应该在测试环境或者在Oracle Support的支持下使用。
在使用进一步的测试中，试图通过switch logfile进行日志切换，结果重起居然报出日志文件损坏。

SQL> startup
ORACLE instance started.

Total System Global Area   97588504 bytes
Fixed Size                   451864 bytes
Variable Size              33554432 bytes
Database Buffers           62914560 bytes
Redo Buffers                 667648 bytes
Database mounted.
Database opened.
SQL> select count(*) from t;
select count(*) from t
                     *
ERROR at line 1:
ORA-00942: table or view does not exist


SQL> create table t as select * from dba_users;

Table created.

SQL> select count(*) from t;

  COUNT(*)
----------
        12

试图通过switch logfile触发检查点:

SQL> alter system switch logfile;

System altered.


SQL> insert into t select * from t;

12 rows created.

SQL> commit;

Commit complete.

SQL> select count(*) from t;

  COUNT(*)
----------
        24

日志文件损坏(未测试是否可以重复出现):

SQL> startup force;
ORACLE instance started.

Total System Global Area   97588504 bytes
Fixed Size                   451864 bytes
Variable Size              33554432 bytes
Database Buffers           62914560 bytes
Redo Buffers                 667648 bytes
Database mounted.
ORA-00354: corrupt redo log block header
ORA-00353: log corruption near block 3 change 897612314 time 10/19/2005 14:19:34
ORA-00312: online log 3 thread 1: '/opt/oracle/oradata/conner/redo03.log'

损坏的是active的日志文件:

SQL> select * from v$log;

    GROUP#    THREAD#  SEQUENCE#      BYTES    MEMBERS ARC STATUS           FIRST_CHANGE# FIRST_TIM
---------- ---------- ---------- ---------- ---------- --- ---------------- ------------- ---------
         1          1        159   10485760          1 NO  INACTIVE             897592312 19-OCT-05
         2          1        158   10485760          1 NO  INACTIVE             897572310 19-OCT-05
         3          1        160   10485760          1 NO  ACTIVE               897612314 19-OCT-05
         4          1        161    1048576          1 NO  CURRENT              897612440 19-OCT-05

SQL> alter system set "_allow_resetlogs_corruption"=true scope=spfile;

System altered.

SQL> shutdown immediate;
ORA-01109: database not open

Database dismounted.
ORACLE instance shut down.
SQL> startup mount;
ORACLE instance started.

Total System Global Area   97588504 bytes
Fixed Size                   451864 bytes
Variable Size              33554432 bytes
Database Buffers           62914560 bytes
Redo Buffers                 667648 bytes
Database mounted.
SQL> recover database using backup controlfile until cancel;
ORA-00279: change 897612315 generated at 10/19/2005 16:54:18 needed for thread 1
ORA-00289: suggestion : /opt/oracle/oradata/conner/archive/1_160.dbf
ORA-00280: change 897612315 for thread 1 is in sequence #160


Specify log: {=suggested | filename | AUTO | CANCEL}
cancel
ORA-01547: warning: RECOVER succeeded but OPEN RESETLOGS would get error below
ORA-01194: file 1 needs more recovery to be consistent
ORA-01110: data file 1: '/opt/oracle/oradata/conner/system01.dbf'


ORA-01112: media recovery not started


SQL> alter database open resetlogs;

Database altered.

SQL> shutdown immediate;
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup
ORACLE instance started.

Total System Global Area   97588504 bytes
Fixed Size                   451864 bytes
Variable Size              33554432 bytes
Database Buffers           62914560 bytes
Redo Buffers                 667648 bytes
Database mounted.
Database opened.

Fri Jun 10 16:30:25 2005
alter database open resetlogs
Fri Jun 10 16:30:25 2005
RESETLOGS is being done without consistancy checks. This may result
in a corrupted database. The database should be recreated.
RESETLOGS after incomplete recovery UNTIL CHANGE 240677200
Resetting resetlogs activation ID 3171937922 (0xbd0fee82)

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