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RE: LGWR's Writing Habits

From: Shevtsov, Eduard <EShevtsov_at_flagship.ru>
Date: Fri, 15 Dec 2000 13:15:22 +0300
Message-Id: <10711.124668@fatcity.com>


The reason is simple - to find the TRUTH.

>
>
> I'm glad you said this.
> My point is there is no reason for someone to come and say
> my friend in
> Oracle looked at the source code and told me this and that.
> This opens many doors for troubles to the person and his friend.
>
> Regards,
>
> Waleed
>
>
> -----Original Message-----
> Sent: Thursday, December 14, 2000 10:36 AM
> To: Multiple recipients of list ORACLE-L
>
>
> Releasing the source code is grounds for immediate dismissal
> from Oracle and
>
> might in fact be grounds for legal action....
>
> I don't think anyone wants to take that risk, and I
> certainly don't want to
> be the cause of such actions by asking someone to do it.
>
> And Gaja didn't say he had access to the code, he said he
> had a friend who
> had access, so yes, he had to speculate before checking with
> his friend.
>
>
> >From: "Khedr, Waleed" <Waleed.Khedr_at_FMR.COM>
> >Reply-To: ORACLE-L_at_fatcity.com
> >To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
> >Subject: RE: LGWR's Writing Habits
> >Date: Wed, 13 Dec 2000 12:56:18 -0800
> >
> >
> >I do not understand if you have access to the source code
> then why do you
> >have to speculate about LGWR behavior?
> >
> >Also it could be a good idea to ask your friend in Oracle
> to post some of
> >the source code here in this list so that we can answer many of the
> >questions we have.
> >
> >
> >-----Original Message-----
> >Sent: Wednesday, December 13, 2000 12:45 PM
> >To: Multiple recipients of list ORACLE-L
> >
> >
> >Hello everyone,
> >
> >A couple of days ago I had posted a response to someone's query
> >about copy latches and in that discussion I had mentioned that
> >the 1/3 full event of the redo log buffer will really not 'kick
> >in' unless log_buffer is set to at least 1Mb. I must confess
> >that the number here is actually 3Mb and not 1Mb as posted
> >before. I apologize for that typo.
> >
> >However, the fact remains that from Oracle8, LGWR will not be
> >posted by the 1/3rd full event of the redo log buffer, unless
> >there are at least 1 Mb worth of redo entries in the log_buffer.
> >In my previous posting, I said that for this to occur the
> >log_buffer should be sized at least 1 Mb, but that number is
> >actually even higher - 3 Mb.
> >
> >And the rationale behind that stems from the events on which
> >LGWR writes to disk. They are as follows:
> >
> >1) Every 3 secs (independent of DBWR, yes this has been proven
> >to be true by testing and looking up the source code).
> >2) On a Commit.
> >3) When DBWR posts LGWR to write. (This is to make sure that the
> >redo entires are written before 'dirty' blocks are written to
> >disk).
> >4) On checkpoints.
> >5) When the log_buffer is 1/3rd full, but subject to the
> >following formula MAX(1 Mb., log_buffer/3), i.e., at least 1 Mb
> >of redo entries need to be there, for the 1/3 event to occur.
> >
> >Now let's think about this for a minute. Realistically the need
> >for the 1/3rd full event is not that critical, as events 1-4
> >will take care of getting the redo entries down to disk. And
> >this in no way will cause more 'log buffer space' waits than
> >what the system is already experiencing.
> >
> >To make doubly sure that I was not 'under the influence', I
> >called a very good friend of mine at Oracle, and had him check
> >the source code for 8.0.5, and he corroborated my claim. We are
> >doing some further digging, to determine whether 'all' or 'one'
> >of the redo copy latches are used to protect the buffer, while
> >'flushing' the entire contents of the log_buffer. There are 2
> >references to this (one mentioning 1 copy latch and the other
> >mentioning all copy latches) and we will get to the bottom of
> >that and I will then post our findings.
> >
> >End of technical stuff;
> >
> >********************************************************
> >Begin non-technical stuff;
> >
> >When I originally posted that the 1/3rd full event has changed
> >in functionality in Oracle8, it was termed as a 'ludicrous
> >suggestion'. Now, that comment may have gone 'just a bit too
> >far' to my personal comfort, as it was directed against me
> >'point blank'. I just could not hit the 'delete key' on that
> >one.
> >
> >In light of all the 'country of origin' and 'ethnic background'
> >stuff that has gone through our list in the past couple of days,
> >I humbly urge all of us to exercise some caution in our
> >communications. This is an forum where we cannot guage the
> >poster's feelings, hence we need to make sure that we are
> >sensitive to the reader's feelings.
> >
> >While it is absolutely OK to question the contents of a posting,
> >please do it in a manner that is 'amicable'. After all, we are
> >human beings first, aside of our ethnic, cultural, religious and
> >political backgrounds. Let's try to respect thatm core fact.
> >
> >When I met Jared approx. 3 years ago at an IOUG-A conference, we
> >talked about creating an Oracle listserv to 'share relevant and
> >accurate information'. I don't think Jared or any one of us,
> >would want this to become 'electronic battleground' for food
> >fights or to be a forum to 'force and assert one's technical or
> >personal ego'.
> >
> >This list today has a few thousand individuals from all corners
> >of the world, and all of us contribute to the best of our
> >abilities. Let's continue the great technical content exchange
> >that we have had and let's do that with 'respect for the
> >reader'. Thanks for your patience, tolerance and technical
> >prowess.
> >
> >End non-technical stuff;
> >
> >********************************************************
> >
> >Seasons Greetings,
> >
> >Gaja
> >
> >
> >=====
> >Gaja Krishna Vaidyanatha
> >Director, Storage Management Products, Quest Software Inc.
> >Office : (972)-304-1170, E-mail : gaja_at_quest.com
> >
> >Author:Oracle Performance 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
> >
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> >Author: Khedr, Waleed
> > INET: Waleed.Khedr_at_FMR.COM
> >
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Author: Khedr, Waleed
  INET: Waleed.Khedr_at_FMR.COM

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Received on Fri Dec 15 2000 - 04:15:22 CST

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