REDO LOG Concepts

From: DBA Deepak <oracle.tutorials_at_gmail.com>
Date: Thu, 17 May 2007 07:40:05 +0530
Message-ID: <75aa80160705161910g3e806456j4ecf933a9085440a@mail.gmail.com>

Hi All,

As we know when we issue a COMMIT the log buffer content is flushed to the online redo log file before the "Commit complete" status is returned to the user. Please correct me if I am wrong.

I have the following scenario...

SQL> select member from v$logfile;

MEMBER

---

/u04/oradata/BIDWDB01/redo03.log
/u04/oradata/BIDWDB01/redo02.log
/u04/oradata/BIDWDB01/redo01.log

SQL> !rm /u04/oradata/BIDWDB01/redo01.log

SQL> !rm /u04/oradata/BIDWDB01/redo02.log

SQL> !rm /u04/oradata/BIDWDB01/redo03.log

SQL> connect scott/oracle
Connected.
SQL> update emp set ename=ename;

14 rows updated.

SQL> commit;

Commit complete.

SQL> commit;

Commit complete.

SQL> conn / as sysdba
Connected.
SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.

SQL> startup
ORACLE instance started.

Total System Global Area 4479516672 bytes

Fixed Size            1984504 bytes
Variable Size        905975816 bytes
Database Buffers      3556769792 bytes
Redo Buffers          14786560 bytes

Database mounted.
ORA-00313: open failed for members of log group 1 of thread 1 ORA-00312: online log 1 thread 1: '/u04/oradata/BIDWDB01/redo01.log'

---

My question is even after deleting all the online redo log files how did Oracle returned the Commit complete status to the user? What happened to the log buffer data flush?

I am using 10.2.0.2 on Solaris 9 (64-bit)

Regards,

Deepak

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Received on Wed May 16 2007 - 21:10:05 CDT