Voodoo with init parameters and Oracle Restart

Uwe Kirchhoff, one of the best techies I know in the entire Oracle CSS (formerly ACS) Support, mailed me before the Christmas holidays with a simple question. He discovered that altering init.ora parameters in a session does not necessarily write the parameter down into the spfile. Sounds a bit like Voodoo with init parameters,  and Oracle Restart has a role in this story as well. If you don’t have or do not plan to use Oracle Restart, then this is not interesting for you. But of course, you are free to still read it 🙂

Voodoo with init parameters and Oracle Restart

Photo by Marko Manojlovic on

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DBMS_OPTIM_BUNDLE and disabling another fix

Yes, DBMS_OPTIM_BUNDLE week it is. As I received so many good questions and input after my blog post whether you should enable _fix_controls with DBMS_OPTIM_BUNDLE or not, now I can easily fill the rest of the week with new content. Today it will be about a customer’s question regarding DBMS_OPTIM_BUNDLE and disabling another fix.

Disabling another fix

The setup is pretty simple. Stefan wanted to disable a different fix while he had all fixes from the most recent RU enabled on purpose. Sounds simple but has a dangerous pitfall.

This is what …

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UNDO_RETENTION not inherited to PDBs anymore since 19.9.0

Behavior changes introduced via a bug fix may not be something you like a lot. And thanks to Sreedhar from one of our most important customers I learned on the weekend: UNDO_RETENTION not inherited to PDBs anymore since 19.9.0.

UNDO_RETENTION not inherited to PDBs anymore since 19.9.0

Photo by Ben Wicks on Unsplash

What is happening before 19.9.0?

Until Oracle 19.8.0 you could change the UNDO_RETENTION in the CDB$ROOT, and it applied to all PDBs automatically. You may or may not have cared. But there are cases when you’d like to change an undo related parameter in the CDB$ROOT without its propagation into all PDBs.

This behavior …

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ORA-1555 won’t get reported into alert.log anymore since 19.4.0

Many thanks to a German customer for showing me this tiny behavior change with Oracle Database RU 19.4.0. From this RU on the well known ORA-1555 won’t get reported into alert.log anymore since 19.4.0. But if you still like to see the “snapshot too old” error, then you can use a workaround.

Why has this been changed?

Actually this is something I don’t understand completely. It may be just a side effect. Unpublished fix bug 29424999 – DUMP MINIMAL DIAGNOSTICS BY DEFAULT IN CASE OF ORA-01555 IN ADW/ATP ENV has been

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Config file for AutoUpgrade – Tweaking init parameters

In the previous blog posts I explained how to generate a sample config file for the AutoUpgrade tool and how to adjust it. Then I gave you an overview about the most important Advanced Options you may want or need to deal with when using the utility. And in the below blog post I would like to show you have you need to edit the Config file for AutoUpgrade – Tweaking init parameters is an important topic.

This is the forth post of a series of blog posts regarding the new AutoUpgrade tool. Please find all the other available …

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Oracle 12.2 underscores appear in SPFILE – be aware when you flashback

Oracle 12.2 underscores appear in SPFILE - be aware when you flashbackI did blog in the past weeks about Fallback Strategies with Flashback Database. But two of my reference customers came across an interesting issue when they tried to fallback: Oracle 12.2 underscores appear in the SPFILE – magically – and prevent the fallback using the existing SPFILE.

Oracle 12.2 underscores appear in SPFILE – be aware when you flashback

In one case it happened during a test, in the other case it happened during a live fallback after the Data Guard Broker has interfered with the upgrade causing real trouble. In both cases the SPFILE sits in ASM.

Both …

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New SPFILE parameters in Oracle Database with July 2016 (and newer) PSU/BP

New Parameters in Oracle Database with July 2016 PSU/BP

By following an internal discussion and checking parameter changes between Patch Set Updates (PSU) and Proactive Bundle Patches (BP) I learned that we introduced two new SPFILE parameters in Oracle Database with the July PSU and BP. One is documented in the patch readme, the other one can be found right now only in the Oracle Database manual:

The Oracle 12.2 documentation about ALLOW_GROUP_ACCESS_TO_SGA, the parameter which appears not in the Oracle 12.1 documentation right now, says:

ALLOW_GROUP_ACCESS_TO_SGA controls group access to shared memory

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Default Changes SPFILE Parameters – Oracle 12.2

This is the 4th posting in my series about init.ora/SPFILE parameters in Oracle Database

Roy and I did a comparison between default parameter settings in Oracle Database vs Oracle Database vs Oracle Database And some changes are quite interesting – of course the memory driven parameters are left out in this list.

Color RED marks a change between releases.
The databases were …

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SPFILE Parameter: max_pdbs – a must for Single Tenant

Sometimes my job has a aspect making me smile at the end of the day 😉

I sat together with Johannes Ahrends during a talk at the OUGN Conference on the boat from Oslo towards Kiel. And we were discussing afterwards why there’s no official way to limit the number of PDBs which will be essential for customers wanting to go the Single Tenant track. I had my Hands-On environment up and we played a bit in the break recognizing that a constraint on CONTAINER$ won’t be the correct solution as unplug/plug operations leave leftovers in it unless you …

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Deprecated Parameters in Oracle Database

This is the 3rd posting in my series about init.ora/SPFILE parameters in Oracle Database


Finally, here’s the list of DEPRECATED parameters in Oracle Database


Only the ones in BOLD were newly marked as DEPRECATED in Oracle Database …

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Obsolete SPFILE Parameters in Oracle Database

This is the 2nd posting in my series about init.ora/SPFILE parameters in Oracle Database

Find the list of the 159 obsoleted parameters here (and of course in V$OBSOLETE_PARAMETERS):

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New SPFILE parameters in Oracle Database

This is the 1st posting in my series about init.ora/SPFILE parameters in Oracle Database

Oracle Database is available now in the Oracle Cloud.

And this is the list of 46 new init.ora/spfile parameters compared to Oracle Database – including the links (where possible) to the Oracle Database 12.2 Reference documentation.




allow_global_dblinks LDAP lookup for DBLINKS
allow_group_access_to_sga Allow read access for SGA
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New (some undocumented) Parameters in Oracle

Every release offers some surprises – even to myself 😉

Right now Roy and I are in the final steps to refresh our big slide deck to the new layout, but more important, to have Oracle information included as well (were necessary). So I did my usual “compare parameters” query between releases – getting unusual surprises this time.

This is the list of new parameters introduced with the patch set Oracle Database Where applicable I have added the link to the doc.

But as you may recognize not all of them are explained in the doc 😉

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Parameter _rollback_segment_count can cause trouble

Just some weeks ago we’ve learned that setting the hidden underscore parameter:


may cause trouble during upgrade. This parameter is used in very rare cases to have under all circumstances and situations this specified number of UNDO’s online. Now during upgrade this may result in massive latch contention  – and there’s a patch available as well. Recommendation is to unset it during upgrade.

I don’t think that many people will hit this as I personally haven’t seen databases with this underscore in their init.ora or spfiles. So take this post more or less as a reminder …

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Upgrade – and an interesting surprise

Patchset is out there for a long, looong time. But still Roy and me – and unfortunately our customers – sometimes experience some nice surprises after upgrade.

Roy did work on the weekend with a financial institution customer in the US to support them during their go-live on Oracle with several systems. It was well tested and long planned. And overall the whole process went well except for one database (see Roy’s entry below on the change with JOB_QUEUE_PROCESSES in

Yesterday I’ve received a text message from Roy to have a closer look into a service request …

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DBMS_SCHEDULER jobs stuck after upgrade to 11.2? Check this parameter!

I think I learn something new practically every time that I talk to or work with customers. Here’s a nugget of information that may be worth its weight in gold if you are upgrading in a RAC environment. You might find after the upgrade that your DBMS_SCHEDULER jobs seem to be scheduled but unable to run, as if the scheduler is stuck for some reason.

The reason for this is an interesting parameter job_queue_processes whose behavior changed in 11.2. The parameter itself has been around for a long time, but here is the important note from the 11.2 Upgrade

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New hidden parameters in Oracle 11.2

We really welcome every external review of our slides. And also recommendations from customers visiting our workshops.

So it happened to me more than a week ago that Marco Patzwahl, the owner of MuniqSoft GmbH, had a very lengthy train ride in Germany (as the engine drivers go on strike this week it could have become even worse) and nothing better to do than reviewing our slide set. And he had plenty of recommendations.

Besides that he pointed us to something at least I was not aware of and added it to the slides:

In patch set …

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