thanks for explaination. I did read the manuals
but I thought like DBWR process is responsible for writing to data files
similarly there would be a separate process like RBWR or sth to write dirty
Rollback buffers in Rollbak files. Also nowhere in concepts manual did I
find ( SGA diagram or elsewhere) that Rollback segments are in memory . only
things they talk about is DATA buffers and redo log buffers and hence the
confusion.
So thanks again .
Regards,
Mandeep
-----Original Message-----
From: Gaja Krishna Vaidyanatha [mailto:gajav_at_yahoo.com]
Sent: Friday, November 17, 2000 1:05 AM
To: Multiple recipients of list ORACLE-L
Subject: RE: Rollback segments confusion ?
Mandeep,
I am not sure what you mean by 'maintenance'. Each server
process that starts a transaction, gets assigned a rollback
segment and it is responsible to read the relevant rollback
segment blocks into the database buffer cache if they are not
already present there, for its use. When these rollback segment
blocks get modified by the tranaction (before image gets written
into it), they become dirty and move into the dirty list.
In due course, DBWR and/or a combination of DBWR I/O slaves
writes the blocks to disk. I don't mean to be rude, but you
might want to start reading the Oracle Concepts Manual, to get
answers for this and other questions that may arise from this.
If you can't find the answers to your questions in the manuals,
please post your questions and someone will be more than happy
to get you some answers.
Enjoy your bedtime reading...;-)
Gaja
- "Bhatia, Mandeep (CAP, CEF)" <Mandeep.Bhatia_at_gecapital.com>
wrote:
> Gaja thanks,
> which process is responsible for these Rollback segments
> maintenance ? is it
> DBW0 or ??
>
>
> Regards,
> Mandeep
>
>
>
> -----Original Message-----
> Sent: Thursday, November 16, 2000 12:21 PM
> To: Multiple recipients of list ORACLE-L
>
>
> Mandeep,
>
> I am not sure what made you think rollback segments are not in
> memory and only on disk. The rollback segment blocks (like all
> other blocks except pure temporary tablespace blocks) are
> modified in memory first, before written to disk. And when a
> block gets modified it becomes dirty, goes on the dirty list
> and
> then eventually gets down to disk. Just like the other blocks.
>
> Hope that helps,
>
> Gaja
>
> --- "Bhatia, Mandeep (CAP, CEF)"
> <Mandeep.Bhatia_at_gecapital.com>
> wrote:
> > Hi Listers,
> > The rollback segment is not in physical memory , it is on
> the
> > disk.
> > for every changing row oracle moves its before image to rbs.
> > does this not make query performance slow ?
> > Kindly verify ?
> > Mandeep
> > --
> > Please see the official ORACLE-L FAQ: http://www.orafaq.com
> > --
> > Author: Bhatia, Mandeep (CAP, CEF)
> > INET: Mandeep.Bhatia_at_gecapital.com
> >
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>
> =====
> Gaja Krishna Vaidyanatha
> Director, Storage Management Products, Quest Software Inc.
> Office : (972)-304-1170, E-mail : gajav_at_yahoo.com
>
> Author - Oracle Tuning 101 by Osborne McGraw-Hill
> "Opinions and views expressed are my own and not of Quest"
>
> __________________________________________________
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> Please see the official ORACLE-L FAQ: http://www.orafaq.com
> --
> Author: Gaja Krishna Vaidyanatha
> INET: gajav_at_yahoo.com
>
> Fat City Network Services -- (858) 538-5051 FAX: (858)
> 538-5051
> San Diego, California -- Public Internet access /
> Mailing Lists
>
> To REMOVE yourself from this mailing list, send an E-Mail
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> (or the name of mailing list you want to be removed from).
> You may
> also send the HELP command for other information (like
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> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.com
> --
> Author: Bhatia, Mandeep (CAP, CEF)
> INET: Mandeep.Bhatia_at_gecapital.com
>
> Fat City Network Services -- (858) 538-5051 FAX: (858)
> 538-5051
> San Diego, California -- Public Internet access /
> Mailing Lists
>
> To REMOVE yourself from this mailing list, send an E-Mail
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> You may
> also send the HELP command for other information (like
subscribing).
Gaja Krishna Vaidyanatha
Director, Storage Management Products, Quest Software Inc.
Office : (972)-304-1170, E-mail : gajav_at_yahoo.com
Author - Oracle Tuning 101 by Osborne McGraw-Hill
"Opinions and views expressed are my own and not of Quest"
Do You Yahoo!?
Yahoo! Calendar - Get organized for the holidays!
http://calendar.yahoo.com/
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Please see the official ORACLE-L FAQ: http://www.orafaq.com
--
Author: Gaja Krishna Vaidyanatha
INET: gajav_at_yahoo.com
Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051
San Diego, California -- Public Internet access / Mailing Lists
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Received on Fri Nov 17 2000 - 10:08:38 CST
