Re: Deferred Transaction Recoverability

From: Dino Hsu <dino1_at_ms1.hinet.net>
Date: Fri, 24 Aug 2001 11:09:41 +0800
Message-ID: <m1gbotgila8ll9ls7vqjcptnau7260u0jj@4ax.com>

On Thu, 23 Aug 2001 16:07:51 GMT, nsouto_at_optushome.com.au.nospam (Nuno Souto) wrote:

>snip

Nuno has brought me out of the dark as to datafiles, logfiles and rollback segments. I try to summarize here:

1.Logfiles is more of 'instance recovery'
2.Rollback segments is more of 'transaction management'
3.The reason I was confused is it's nothing wrong to call 'transaction

management' as 'transaction recovery'. However, they are meant to deal with different problems, they can work closely together but should not be mixed up.
4.On the next system startup after an instance failure and thus some possible manual procedures from administrators, instance recovery process is started by SMON, in which logfiles are involved first (control files, datafiles, logfiles are 'synchronized'), and datafiles and rollback segments later (transaction recovery 'deferred') as is also performed in normal times.
5.Both for instance recovery and transaction management, SCNs or System Change Numbers are used to identify transactions.

Dino Received on Thu Aug 23 2001 - 22:09:41 CDT