Re: Database upgrade hacking

  • From: Marcin Przepiorowski <pioro1@xxxxxxxxx>
  • To: Laimutis.Nedzinskas@xxxxxx
  • Date: Sun, 19 May 2013 12:57:10 +0100

Hi Laimis,
If I remember correctly you can't change compatible parameter when you have
an restore point created.
Anyway your approach is correct - flashback database will undo all upgrade
steps and if you want to be 100 % sure do a copy of control file after you
have created restore point and before you have started upgrade.

regards,
Marcin


On Fri, May 17, 2013 at 10:21 AM, <Laimutis.Nedzinskas@xxxxxx> wrote:

> Hi
>
> I've tested with success a rollback of upgrade from 10.2 to 11.2.
> Is such a rollback is supported or not ?
>
> The steps were:
>
> - leave parameter compatible .2.0
> - do all documented pre-migrations steps
> - startup upgrade
> - create guaranteed flashbak point
> - run @catupgrd.sql
> - open database
> - now suppose a problem is detected and rollback decision is taken:
>
> - flashbacked database to the restore point
> - opened database with 10.2 binaries
> - startup: startup mounted the database but open requested "ORA-01589: must
> use RESETLOGS or NORESETLOGS option for database open"
> - alter database open resetlogs: Database altered.
> That's it. The database opened and running.
>
> The idea is that until database does not upgrade datafile headers in
> uncompatible manner all the rest does not really matter. Parameter files
> and control files can be delt with.
> Changes to the dictionary are delt with by flashback.
> Redo logs should not be important after flaashback to the point right after
> "startup upgrade" (it should be possible to create a restore point after
> mount and only then open the database with migrate option but I haven't
> tested that yet)
> Anything else I am missing ?
>
> The database is opened for read-write. If in doubt you have a time to
> replicate it to a supported instance. Looks like in some cases it is a
> better alternative than to restore from backup ?
>
>
> Brgds, Laimis N
>
>
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>
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>
>


-- 
Marcin Przepiorowski
http://oracleprof.blogspot.com


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