Best Practice

Patching recommendations: Which route is the best? RUs, MRPs, n-1??

Be aware, this is a longer Monday blog post. Upfront, I am not the master of patching. And I clearly see that many of you struggle with the current situation. Not only regarding Oracle software but I guess, this extends to almost every software or OS. Since I get asked almost daily about the ideal approach, and since we discuss these topics internally across the tech teams as well, I thought I would share here my personal Patching recommendations: Which route is the best? RUs, MRPs, n-1??

Patching recommendations: Which route is the best? RUs, MRPs, n-1??

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Prelude

Two important things I’d like to …

Were you aware of the two hidden columns in CDB-Views?

Posted on August 11, 2025 by Mike.Dietrich Best Practice Single-/Multitenant 14

Learning something new every day is the best part of my job. And as you can see and read on the blog, thanks to YOU, I learn a lot. This one I learned from Johannes Ahrends at my workshop for ora2know in Munich in early July this year. Were you aware of the two hidden columns in CDB-Views? I confess honestly: I wasn’t.

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Two hidden columns?

Johannes asked me whether I know the reason for the two hidden columns in every CDB-view. His question was more like: It’s super-useful but why are these hidden?…

Who’s who in CDB_SERVICES, SERVICE$, and more?

Posted on February 4, 2025 by Mike.Dietrich Best Practice 6

I visited a customer recently, and they will use Refreshable Clone PDBs to move from Oracle Database 19c to Oracle Database 23ai. So far, nothing special. But after cloning there was an issue with the services creation with srvctl. We started querying the various views in the database, found some divergence but no good MOS note or documentation listing all the differences. Maybe this blog post will help a bit to shed some light.

Who's who in CDB_SERVICES, SERVICE$, and more?

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Why do you need to take care on services?

Daniel has described this very nicely the other week in …

Reuse Object IDs in Oracle Database 19c and 23ai

Posted on July 4, 2024 by Mike.Dietrich Behavior Change Best Practice Oracle Database 19c Oracle Database 23ai 12

I love to learn something new every day. And thanks to my Dutch friend, Robert Pastijn, I learned about a limitation of how many objects you can create in an Oracle database. Nothing to worry about, the limit is very high at a little bit over 4.2 billion. But in order to prevent hitting it, we introduced a mechanism to Reuse Object IDs in Oracle Database 19c and 23ai.

Reuse Object IDs in Oracle Database 19c and 23ai

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What is the mechanism?

First of all, this is ON and enabled in Oracle Database 23ai by default. But in case you need this …

Why isn’t the newest JDK in this Oracle Release Update?

Posted on June 20, 2024 by Mike.Dietrich Best Practice 7

Quick blog post only since I received this question 3x this week in various ways from customers. Why isn’t the newest JDK in this Oracle Release Update? Let me try to answer and explain it.

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JDK in the Oracle Home

Actually, when you look at your Oracle Home, you will find a subdirectory:

/u01/app/oracle/product/19/jdk
$ tree -L 1
.
├── bin
├── COPYRIGHT
├── include
├── javafx-src.zip
├── jmc.txt
├── jre
├── jvisualvm.txt
├── legal
├── lib
├── LICENSE
├── README.html
├── release
├── THIRDPARTYLICENSEREADME-JAVAFX.txt
└── THIRDPARTYLICENSEREADME.txt

And in the bin directory, there is …

The downsides of in-place patching – and a patching lab

Posted on January 10, 2024 by Mike.Dietrich Best Practice Patch Recommendation 40

Happy New Year to all of you at first. I hope you all had a good start – and for myself, I promise to blog a bit more again in 2024. Let me start with my first post since I received a question very often: Why should I patch out-of-place with a new Oracle Home? Since I need to patch a bit today I can easily show the downsides of in-place patching – and a patching lab.

The downsides of in-place patching - and a patching lab

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It all started at OCW 2023

Ok, we didn’t really start it at OCW 2023 in …

Important clarifications to the Oracle Database Error Correction Policy

Posted on October 19, 2023 by Mike.Dietrich Best Practice Patch Recommendation Release Schedule 4

When I came back from vacation a few weeks ago (or was it almost 2 months ago??) I learned that we have added some Important clarifications to the Oracle Database Error Correction Policy. The clarifications are mainly about how long you will be able to request a single fix for a given Release Update (RU). Take this not as a constraint but a motivation to argue internally to not stay on too old Release Updates.

Important clarifications to the Oracle Database Error Correction Policy

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How to find the important notes?

It is not easy to find this important note in MOS, …

Zero Downtime Upgrade of Timezone Data in Oracle 21c and 23c?

Posted on June 6, 2023 by Mike.Dietrich Best Practice Oracle Database 21c Oracle Database 23ai Time Zone - DST 6

There is a feature in Oracle Database 21c I planned to write about for a very long time: Zero Downtime Upgrade of Timezone Data in Oracle 21c and 23c. This sounds very promising – but let us take a closer look together in this blog post.

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Time Zone Upgrade?

There is of course an ongoing discussion whether and when you should upgrade the DST version of your database to a current value. Since we all live in a more and more globalized world, this topic becomes more and more important. Even more important …

Virtual Classroom Seminar #15: Data Pump Best Practices on April 5, 2023

Posted on March 23, 2023 by Mike.Dietrich Best Practice Data Pump Workshop 4

We are quite busy these days. And I am lagging behind in answering your comments on the blog. So please be patient, nothing will be lost. Meanwhile, we work hard on the slides for our next Virtual Classroom Seminar #15: Data Pump Best Practices on April 5, 2023.

Virtual Classroom Seminar #15: Data Pump Best Practices on April 5, 2023

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What will be the topic?

Data Pump Best Practices and Real World Scenarios tells you already what we are planning to do. After we had a “Data Pump Deep Dive with Development” seminar last year (time flies so quickly), we decided that we should tackle …

A change in Oracle 12.2 and 19c with MV Refresh Stats Collection

Posted on November 23, 2022 by Mike.Dietrich Best Practice Upgrade / Migration 6

It’s not easy for me to put the topic into a searchable title for this blog post. The feature or change I will write about today came in actually with Oracle Database 12.2.0.1. But since many of you will move directly from Oracle 11.2.0.4 or 12.1.0.2 to 19c, the Long Term Support release, it may affect you as well. So let me explain a change in Oracle 12.2 and 19c with MV Refresh Stats Collection.

A change in Oracle 12.2 and 19c with MV Refresh Stats Collection

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A customer story

The local Support team asked me a few weeks ago whether I have heard …

Certifying an application on a specific RU-only is wrong

Posted on September 14, 2022 by Mike.Dietrich Best Practice Patch Recommendation Release Schedule 15

Well, there are still 80+ comments I need to answer and reply to on the blog. So please be patient – nothing gets deleted or ignored. But it happens that a topic crosses my inbox, and I need to blog about it right now. Today, it is a case where a customer asked me for advice, and mentioned on the side that they are going to 19.6.0 in OCI. In this relation I’d like to explain why Certifying an application on a specific RU- only is wrong.

Certifying an application on a specific RU only is wrong

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What’s the story?

At first, …

Can I cleanup the previous Patch Bundles with opatch?

Posted on January 21, 2022 by Mike.Dietrich Best Practice Patch Recommendation 36

Addition May 16, 2023:

Before you read on, better jump to this blog post. With opatch 37, released in April 2023, a cleanup option is available – and this significantly improves performance:

Cleaning up older patch artifacts – and improve opatch performance

Today I will step on mined territory. Can I cleanup the previous Patch Bundles with opatch? Or can I just wipe out the old ones? That is a question which will bring people with temper quickly close to explosion. But let me start step by step, especially for those of you who aren’t familiar with this topic.…

Upgrade Seminars 1 and 2 – A quick recap, slides download and more

Posted on June 25, 2020 by Mike.Dietrich Best Practice Workshop 2

Thank you for participating in the first two seminars. Roy and I did already the “Release and Patching Strategy” webinar on Tuesday, June 23. And today “AutoUpgrade to Oracle 19c”. So it time for Upgrade Seminars 1 and 2 – A quick recap, slides download and more.

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Slides Download

I uploaded the slides already to https://mikedietrichde.com/slides/#WEB2020. Of course, I will upload the other slide decks as well to the same location.

Seminar Recordings

As soon as the recordings page has been completed, we will send out an email. And I will post the links …

Less is more – faster Oracle database upgrades with less memory

Posted on April 30, 2020 by Mike.Dietrich Best Practice 9

The title of this post sounds a bit weird: Less is more – faster Oracle database upgrades with less memory. Just a few weeks ago, I posted about How long will my upgrade take … revisited. And Daniel adds a very useful piece to the upgrade speed topic. Read about his tests below.

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Less is more – faster Oracle database upgrades with less memory

by Daniel Overby Hansen, Senior Principal Product Manager,
Oracle Database Upgrades and Cloud Migrations

Daniel Overby Hansen

Mike and I had a talk with a customer the other …

Oracle Database Upgrade – Quick Start Guide available

Posted on April 6, 2020 by Mike.Dietrich Best Practice 8

If you don’t deal with databases upgrades every day but just want to see a short and good overview about how to do a successful database upgrade, then this is for you. A few days ago we’ve made the Oracle Database Upgrade – Quick Start Guide available for download.

Oracle Database Upgrade - Quick Start Guide available

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Why a Quick Start Guide?

If database upgrades are your daily topic, you won’t need our quick start guide. But if you need a short overview about the right steps to approach an upgrade, this guide is for you. Thanks to my PM colleague, …

How long will my database upgrade take? Revisited …

Posted on March 17, 2020 by Mike.Dietrich Best Practice 6

I received this question twice within a few days. And I remember that a tiny little while ago I wrote something on the blog about it. But as this “while” is 11 years ago, I came to conclusion to refresh this topic – and write something about How long will my database upgrade take? Revisited …

How long will my database upgrade take? Revisited ...

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Is there a query?

At first, before I go into details, an important fact upfront: There is neither any query nor any tool giving you a rough estimate or precise figure of how long your upgrade will …

ORA-1403 during TEXT / CONTEXT post upgrade

Posted on March 5, 2020 by Mike.Dietrich Best Practice Flaws and Pitfalls 8

When you see an ORA-1403 during TEXT / CONTEXT post upgrade phase, regardless of using AutoUpgrade, dbupgrade, catctl or DBUA, no worries. Two people reported this to me this week. And my dear support colleague Klaus Herndl told me about the existing MOS note. But there is a bit more to explain, especially as the bug is non-public and the MOS note doesn’t tell you when this can happen.

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What happens?

This is the error pattern you may see during the post upgrade phase when Oracle Text is installed in your database:

Oracle Database

Be aware when you use _ORACLE_SCRIPT in scripts

Posted on February 10, 2020 by Mike.Dietrich Best Practice 8

Recently I came across this when I gave a Multitenant workshop at a German customer. As part of the workshop I explained the _ORACLE_SCRIPT statements you will find in almost all scripts in ?/rdbms/admin. And one of the DBAs gave me a bright smile. He mentioned: “We use it already everywhere to avoid strange errors”. But be aware when you use _ORACLE_SCRIPT in scripts. I will explain, why this can be dangerous.

Be aware when you use _ORACLE_SCRIPT in scripts

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What does _ORACLE_SCRIPT do?

First of all, this is an underscore parameter. Hence, you won’t find it in the Oracle …

Save Patching Downtime with Oracle Multitenant?

Posted on December 2, 2019 by Mike.Dietrich Best Practice Patch Recommendation Single-/Multitenant 8

At OOW 2019 we announced that you can have up to 3 user-created pluggable databases (PDBs) per container database (CDB) without having a Multitenant license. And in this blog post I’d like to demonstrate how you can save patching downtime with Oracle Multitenant.

The Concept

The idea this entire process settles on is very simple. When you create a fresh container database in the target (already patched!) environment, you don’t have to patch this one. You only have to relocate the PDB from the source into the target CDB. In addition, only datapatch needs to be executed. As the …

When and how should you change COMPATIBLE?

Posted on April 17, 2019 by Mike.Dietrich Best Practice 61

When and how should you change COMPATIBLE?

COMPATIBLE is an almost mystic parameter. It has a default setting for each release. But if you try to find more information what it really does, you won’t be very happy. And in reply to my previous blog post about whether you need to change COMPATIBLE when you apply an RU, I received the following question: When and how should you change COMPATIBLE?

What does COMPATIBLE do?

To find an answer to this question, I consulted the documentation at first. And I found this:

COMPATIBLE
Setting COMPATIBLE ensures that new features do not write data formats or structures

Should you change COMPATIBLE when you apply an RU?

Posted on April 10, 2019 by Mike.Dietrich Best Practice 21

I have a million ideas for blog posts. But I like it even more when people ask me to explain something on the blog which isn’t there yet but may be interesting for others as well. And Robert Ortel mailed me the other day and asked if he should change COMPATIBLE when he applies an RU for Oracle 18c. That’s a good question. And I doubt that the documentation has a good recommendation.

Should you change COMPATIBLE when you apply an RU?

No.

Should you change COMPATIBLE when you apply an RU?

That’s a short blog post this time, isn’t it? 🙂 But honestly, you shouldn’t touch COMPATIBLE for …

Creating CDBs and non-CDBs with less options

Posted on August 8, 2018 by Mike.Dietrich Best Practice DBCA Single-/Multitenant 4

I wanted to write up this blog post a long time ago. When Helen Vanderheide did ask me a few weeks ago if she can omit catoctk.sql during the creation of the database, I realized that I should update my previous blog posts about Creating CDBs and non-CDBs with less options. And of course, the following is usable with non-CDBs as well.

You’ll find an example and especially the component dependency matrix below as well as many links to related blog posts at the end. If you don’t want to read all this, just scroll down to the Summary…

New preupgrade.jar and changes in MOS Note:884522.1

Posted on May 7, 2018 by Mike.Dietrich Best Practice 14

We read and listen to your comments. And that’s why my team mate Byron has added a new preupgrade.jar and changes to MOS Note:884522.1. One reader commented that MOS Note:884522.1 (How to Download and Run Oracle’s Database Pre-Upgrade Utility) does not explain how to “run” the preupgrade tool even though it mentions this in the note’s title.

New preupgrade.jar and changes in MOS Note:884522.1

With MOS Note:884522.1 you can download always the most recent versions of the Oracle 18c and 12.2 preupgrade.jar tools, of the Oracle 12.1.0.2 preupgrd.sql and utluppkg.sql. And you’ll even find the last utlu112i.sql for upgrades …

Oracle Database 18c: A new preupgrade.jar is available

Posted on March 19, 2018 by Mike.Dietrich Best Practice 2

In case you plan to upgrade a database to Oracle Database 18c: A new preupgrade.jar is available for download from MyOracle Support (MOS).

Oracle Database 18c: A new preupgrade.jar is available

Please download it – as always – from MOS Note:884522.1.

The same MOS note will get you also the most recent versions of the preupgrade.jar for Oracle Database 12.2.0.1 upgrades. Of course you can download also all previous incarnations such as preupgrd.sql for 12.1.0.2 upgrades and even utlu112i.sql for 11g upgrades.

What’s new in preupgrade.jar for Oracle 18c upgrades?

There are a few important and good Improvements and …

Multiple Hops – Which should be the intermediate release?

Posted on February 13, 2018 by Mike.Dietrich Best Practice 0

This is a topic which doesn’t come up very often. But if it does come up from time to time, and the documentation may give you advice – but as I realized – it does not always give the best advice. When you have to do multiple hops – which should be your intermediate release?

I posted something about this topic a while back:

Multiple hop upgrades? Execute the matching preupgrade scripts for each hop

What are Multiple Hops?

We speak of multiple hops in relation to database upgrades when your source release does not allow you to upgrade directly …

Best Practice

Prelude

Two hidden columns?

Why do you need to take care on services?

What is the mechanism?

JDK in the Oracle Home

It all started at OCW 2023

How to find the important notes?

Time Zone Upgrade?

What will be the topic?

A customer story

What’s the story?

Slides Download

Seminar Recordings

Less is more – faster Oracle database upgrades with less memory

by Daniel Overby Hansen, Senior Principal Product Manager, Oracle Database Upgrades and Cloud Migrations

Why a Quick Start Guide?

Is there a query?

What happens?

What does _ORACLE_SCRIPT do?

The Concept

What does COMPATIBLE do?

Should you change COMPATIBLE when you apply an RU?

New preupgrade.jar and changes in MOS Note:884522.1

Oracle Database 18c: A new preupgrade.jar is available

What’s new in preupgrade.jar for Oracle 18c upgrades?

What are Multiple Hops?

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by Daniel Overby Hansen, Senior Principal Product Manager,
Oracle Database Upgrades and Cloud Migrations