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Home -> Community -> Mailing Lists -> Oracle-L -> RE: redo logs
Even the UNDO records get written to the redo logs, isn't it?
Regards
Naveen
-----Original Message-----
Sent: Tuesday, May 20, 2003 5:22 AM
To: Multiple recipients of list ORACLE-L
Dennis,
He asked about 'undo'. That is in the rollback segments, or the UNDO tablespace.
Jared
DENNIS WILLIAMS <DWILLIAMS_at_LIFETOUCH.COM>
Sent by: root_at_fatcity.com
05/19/2003 03:37 PM
Please respond to ORACLE-L
To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
cc:
Subject: RE: redo logs
Yes. Remember that Oracle doesn't wait for a commit before it writes redo. It is even possible for uncommitted data to get written to the data files. This is a real performance boost on a busy system. In case of a crash, Oracle must be able to recreate the "before" image of the data.
If you become more interested in this, take a look at LogMiner. Once
you
see all the details in a redo log, you'll be much more impressed with
Oracle's integrity and throughput! And a good time to practice with
LogMiner
is when you aren't under pressure.
Dennis Williams
DBA, 80%OCP, 100% DBA
Lifetouch, Inc.
dwilliams_at_lifetouch.com
-----Original Message-----
Sent: Monday, May 19, 2003 4:58 PM
To: Multiple recipients of list ORACLE-L
Dennis , so what you are trying to say is that the redo logs store undo
data
also ?
> Not every statement is committed. Some are rolled back. So when the
database
> is recovered, these statements must again be rolled back.
>
> Dennis Williams
> DBA, 80%OCP, 100% DBA
> Lifetouch, Inc.
> dwilliams_at_lifetouch.com
>
>
> -----Original Message-----
> Sent: Saturday, May 17, 2003 9:09 PM
> To: Multiple recipients of list ORACLE-L
>
>
> Hello list
>
> the "backup and recovery concepts" manual says :"Each redo record
contains
> both the old and the new values. Oracle also records the old value to an
> undo block located either in a rollback segment (if running in manual
undo
> management mode) or in a dedicated undo tablespace (if running in
automatic
> undo management mode)."
>
> Does this mean that undo data is stored in both the undo tablespace and
the
> redo
> logs ?
>
> I thought that only statements were stored in the redo log file.
>
> If undo data is stored in the redo logs also, then , do we need the undo
> tablespace during recovery ? shouldn't the redo logs be enough ?
>
> --
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> INET: bulbultyagi_at_now-india.net.in
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-- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: <bulbultyagi_at_now-india.net.in INET: bulbultyagi_at_now-india.net.in Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing). -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: DENNIS WILLIAMS INET: DWILLIAMS_at_LIFETOUCH.COM Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing). -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: INET: Jared.Still_at_radisys.com Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing). DISCLAIMER: This message (including attachment if any) is confidential and may be privileged. Before opening attachments please check them for viruses and defects. MindTree Consulting Private Limited (MindTree) will not be responsible for any viruses or defects or any forwarded attachments emanating either from within MindTree or outside. If you have received this message by mistake please notify the sender by return e-mail and delete this message from your system. Any unauthorized use or dissemination of this message in whole or in part is strictly prohibited. Please note that e-mails are susceptible to change and MindTree shall not be liable for any improper, untimely or incomplete transmission. -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Naveen Nahata INET: naveen_nahata_at_mindtree.com Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).Received on Tue May 20 2003 - 08:06:46 CDT
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