Re: why does oracle recovery redo before undo?

From: Mladen Gogala <mgogala_at_adelphia.net>
Date: Mon, 19 Apr 2004 18:09:54 -0400
Message-ID: <20040419220954.GE2115@medo.adelphia.net>

On 04/19/2004 05:28:27 PM, Ryan wrote:

> Now my book says the optimal way to do this is to check for all open transactions at the time of the last checkpoint that have committed after that checkpoint.
>
> Anyone know more? In particularly know 'why'?

It's elementary, my dear Ryan. Oracle has first to recover transactions to roll them back. If the changes recorded in the undo blocks are not applied to the database, how do you propose to roll them back?

-- 
Mladen Gogala
Oracle DBA
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Received on Mon Apr 19 2004 - 17:06:38 CDT