RE: Checkpoint ...

From: <k.sriramkumar_at_iflexsolutions.com>
Date: Sun, 18 Jan 2004 21:09:25 -0800
Message-ID: <F001.005DD2CC.20040118210925@fatcity.com>

Hi Tanel,

Thanks for your inputs. I have given my understanding would request you to provide your inputs.

There are two kinds of checkpoints that happen( Full checkpoint and Incremental Checkpoint)

	Full Checkpoint happens during
	-----------------------------
	
	1. Log switch
	2. Alter system switch logfile
	3. Alter system checkpoint
	4. Tablespace offline
	5. Begin backup mode of a tablespace
	6. Shutdown Normal/Immediate

	A full checkpoint updates the datafile header with the SCN and

updates the controlfile with the SCN

	Incremental Checkpoint happens during
	-------------------------------------

	1. DB_MAX_DIRTY_TARGET(8i)
	2. FAST_START_MTTR_TARGET(9i)
	3. LOG_CHECKPOINT_INTERVAL
	4. FAST_START_IO_TARGET

	A incremental checkpoint updates only the controlfile.

Is my understanding correct?

Thanks and Regards

Sriram Kumar

-----Original Message-----
Sent: Friday, January 16, 2004 9:39 PM
To: Multiple recipients of list ORACLE-L

> > Whenever checkpoint happens datafile header scn and controlfile
> > scn will be in sink. Is my assumption is right? Is there any other
> > scenarios where checkpoint only update controlfile and doesn't
> > update datafile header? Agreed, during "begin backup" mode datafile
> > header will be frozen.. Other than that any scenarios?
>
> Note that not the *whole* header of a datafile is *not* frozen during
backup
> mode, only the checkpoint_scn and checkpoint_time structure in it are
> (+ possibly few others), but for example checkpoint_count for this
> datafile still keeps incrementing due checkpoints.

I got too carried away with "not"-s here... Anyway, the idea is that only few structures in datafile header are frozen during backup mode, but some may change as usual.

Tanel.

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Author: Tanel Poder
  INET: tanel.poder.003_at_mail.ee

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Author: <k.sriramkumar_at_iflexsolutions.com
  INET: k.sriramkumar_at_iflexsolutions.com

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Received on Sun Jan 18 2004 - 23:09:25 CST