RE: oracle downgrade support

From: Thomas Day <tday6_at_csc.com>
Date: Wed, 7 Apr 2004 11:43:52 -0400
Message-ID: <OFC9D2A8F6.E6477988-ON85256E6F.0055F7C6@csc.com>

Would it help if you made the export using the executable (and ORACLE_HOME) of the lower version? I just tested 8.1.6 executable against 9.2.0.4 database and it seemed to work.

                                                                                                                                       
                      DENNIS WILLIAMS                                                                                                  
                      <DWILLIAMS               To:      "'oracle-l_at_freelists.org'" <oracle-l_at_freelists.org>                            
                      @LIFETOUCH.COM>          cc:                                                                                     
                      Sent by:                 Subject: RE: oracle downgrade support                                                   
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                      04/07/2004 11:05                                                                                                 
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Scott

We have pretty much relied on the practice of:

Test the upgrade on a test server and ask users to check it out.
Take a full backup of the server before upgrade.
If there is an issue, decide quickly to go back. Need to decide quickly because transactions since upgrade will be lost.

Fortunately we haven't had a disaster of the magnitude that would require this. I will be interested to see if anyone else has a great solution.

Dennis Williams
DBA
Lifetouch, Inc.
dwilliams_at_lifetouch.com

-----Original Message-----
From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org]On Behalf Of jtesta_at_dmc-it.com Sent: Wednesday, April 07, 2004 9:27 AM
To: oracle-l_at_freelists.org
Cc: Scott.Gamble_at_cardinal.com
Subject: Re: oracle downgrade support

Scott, thats pretty much the idea.

I've been doing backup/recovery scenarios for quite a few years, you have a few options, none which are good.

rebuild the original database with the lower version binaries, attempt and exp/imp, yes imp is only really guaranteed going up in versions not necessarily down.
attempt transportable tablespaces to get the data back into the older version.
attempt to logmine all of the transactions since the upgrade, restore the older version binaries and datafiles, and run the logminer output to get the info back into the older version.

like i said none of them are really good.

wish i had a better answer.

Oracle's stand for downgrades is usually, make a cold backup, and restore that if you need to downgrade, of course losing all transactions since then.

joe

ORIGINAL MESSAGE BELOW ***** I have been reading the thread on tech support with some interest and = was triggered to post.

We are currently in the middle of upgrading all our databases to = 9.2.0.4. Production databases are scheduled to start upgrading next = month and as part of our testing our management requires us to test and

document a downgrade procedure. This is mostly due to a situation that = occurred in our upgrade from 8.0.6->8.1.7 and hitting a crippling
performance bug in 8.1.7 that brought the business almost to a halt. We = struggled through a few weeks of fighting with Oracle support to get = them to accept it as a bug and when they did it was going to be a month = until they had a patch for it. During that time management decided they = could no longer live with the problem and we had to get back to 8.0.6 as = quickly as possible. Well the downgrade procedure failed miserably due = to another issue with the software and it was another week until we were = able to downgrade.

Needless to say management is a bit concerned about major upgrades and = being able to downgrade. Obviously if a major problem is found early = enough restoring the cold backup from before the upgrade is the best = option. But say the bug is not found for 1 week and Oracle cannot fix it

for 1 month.

According to document 208201.1 on metalink downgrading from = 9.2.0.1->8.1.7 is doable. Assuming that patch sets are mostly bug fixes

does that not imply that you can go from 9.2.0.4 to 8.1.7?

We have tested this with 2 databases that mimic 2 of our production = databases. Both have been unsuccessful with 1 having invalid sys objects

after the downgrade and the other getting ora-600's on materialized view = refreshes.

After opening 2 different tars with oracle for these issues they have = both come back with slightly different answers 1) database downgrades = are not supported 2) downgrading from a patch set is not supported = (meaning 9.2.0.4) only downgrading from the base release of 9.2.0.1. = There answer was in both cases to restore the cold backup from prior to

the upgrade or import/export to downgrade.

Does it really seem correct that Oracle does not support downgrades or = are we just hitting bad information from support?

Scott Gamble
Oracle DBA - ERP and DB Technology Engineering=20 Cardinal Health, Medical Products and Services (847)-578-5673 scott.gamble_at_cardinal.com

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Received on Wed Apr 07 2004 - 13:42:47 CDT