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Re: Back to the future

From: Howard J. Rogers <howardjr_at_www.com>
Date: Thu, 6 Sep 2001 05:46:43 +1000
Message-ID: <3b968023@news.iprimus.com.au>


First, you've now got Log Miner. So it's possible to find out to the exact second when a table was dropped (in 8i, it's tricky, because the drop is merely recorded as a 'delete' on the obj$ table, but assuming you aren't legitimately dropping objects left, right and centre, you should still be able to track the offending operation down).

Second, there's the alert log that will reocrd dramas like 'drop tablespace', timed to the second.

Third, if you take a precautionary backup of the control file and the online redo logs before you start the recovery, it is repeatable in case of error. If you open the database and discover you've rolled forward past the error, you simply shutdown, restore the control files and redo logs from the precautionary backup, and all the datafiles from your 'real' backup, and do it again. So it's not irretrievable.

Fourth, you have tools like export and import to help you avoid performing incomplete recoveries in the first place.

So, in summary: you're right that you can't see what's going on as you do it, but with a bit of judicious research and some sensible precautions, it's not quite the 'flying blind in the dark' operation you make it sound to be.

Regards
HJR "Dino Hsu" <dino1.nospam_at_ms1.hinet.net> wrote in message news:b06cpt4kd56jtgcehupqguumo2d436r4s9_at_4ax.com...
> Dear all,
>
> I've just studied the backup and recovery part, and I learned about
> the incomplete recovery and realize that the database can roll forward
> from a baseline backup using log files, this is like 'going back to
> the future'. We can issue 'recover database until canel' to roll
> forward to a point in time. However, without 'WYSWYG' and 'rewind'
> functions, I would assume it's difficult to reach the exact point in
> time. For example, your user tells you he inadvertently dropped a
> table at around 10:00, but nobody knows the exact time, when you
> recover to the 10:00 point, you cannot see the data on the run because
> the database is not opened yet. If the actual time is 09:50, and you
> open the database at the 10:00 point (resetlog), only to see the table
> is still missing, you can do nothing except to start over again. This
> is just like when the police is investigating on a robery case, they
> check the video tape trying to get to the point in time, with 'WYSWYG'
> and forward/backward functions, it's quite easy. But without 'WYSWYG'
> and backward functions, it's time-consuming to narrow the way down
> there.
>
> I am bothered by this thought, anyone enlightens me? Thanks in
> advance.
>
> Dino
>
Received on Wed Sep 05 2001 - 14:46:43 CDT

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