Flaws and Pitfalls

MGA Issue – and it is fixed with Oracle 19.8.0 and newer

Posted on August 20, 2020 by Mike.Dietrich ASM / RAC / GI Flaws and Pitfalls 6

Where do I start? One of the customer accounts I worked the longest time with recently upgraded to Oracle 19c on Exadata. They are an Exadata customer since 2009. After going live on 19c, a few days later they hit an MGA Issue – and it is fixed with Oracle 19.8.0 and newer. But question no.1 was: Why hasn’t Oracle warned us – and how could we have learned about it?

MGA Issue - and it is fixed with Oracle 19.8.0 and newer

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What is the MGA?

OK, I have heard of SGA and PGA. But MGA? The first two hits when I search with …

AutoUpgrade and the Partial Offline Backup Strategy

In our Fallback talk we promote a backup strategy for large DWHs and database which are on purpose in NOARCHIVELOG mode. But last week I learned that there is something important to know about AutoUpgrade and the Partial Offline Backup Strategy. Otherwise you may hit a

AutoUpgrade and the Partial Offline Backup Strategy

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pitfall.

Partial Offline Backup Strategy?

I won’t explain in all details what this is. If you’d like to read more, please find all the necessary information on my blog post from July 17, 2018:

Fallback Strategy: Partial Offline Backup

with graphics included. In brief, you take …

Windows Only: Upgrade to Oracle 18.10.0 fails with ORA-01722

Posted on July 8, 2020 by Mike.Dietrich Flaws and Pitfalls Microsoft Windows 0

Liron Amitzi reported this on his blog a few days ago already. And it is a very nasty tiny little issue happening with RUs where the second number of the release enters the two-digit-space, such as 18.10.0. At this point, on Windows Only: Upgrade to Oracle 18.10.0 fails with ORA-01722. This happens late in the upgrade phase.

Windows Only: Upgrade to Oracle 18.10.0 fails with ORA-01722

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What is the issue?

The problem here is a tiny little piece in %ORACLE_HOME\admin\catupstr.sql – a SUBSTR function is used in a way that it does not take into account a potential two-digit …

Special characters show junk in CLOB columns after upgrade to Oracle 19.7.0 with JDBC

Posted on June 22, 2020 by Mike.Dietrich Flaws and Pitfalls 29

When you’d copy & paste the above title into a search engine, you may come across a very similar sounding blog post I wrote two years ago. Today, my dear colleague Dirk asked me on behalf of a customer if it’s possible that this bug is back in 19.7.0. Of course, I said “No”, for sure not. Bug 26380097 was fixed in Oracle 18c already. Gladly, Dirk insisted. So I checked the SR his customer opened.

Special characters show junk in CLOB columns after upgrade to Oracle 19.7.0 with JDBC

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And now I can write an unplanned blog post about Special characters show junk in CLOB columns …

OJVM datapatch fails with ORA-29532 – but the root cause is noncdb_to_pdb.sql

Posted on April 20, 2020 by Mike.Dietrich Flaws and Pitfalls JVM 2

Kudos to Robert Ortel who brought this nice misbehavior to my attention. And even though it looks like this would be an OJVM issue, it is caused by noncdb_to_pdb,sql, the script which is used to convert a non-CDB to a PDB. When you apply an OJVM patch, OJVM datapatch fails with ORA-29532 – but the root cause is noncdb_to_pdb.sql.

OJVM datapatch fails with ORA-29532 - but the root cause is noncdb_to_pdb.sql

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It’s a bit tricky

First things first. This is not a blog post to blame OJVM. The problem just happens because datapatch for an OJVM patch touches data in the dictionary which hasn’t …

OPatch Alert: Be aware of cleanup issues – and the JDK version

Posted on April 17, 2020 by Mike.Dietrich Flaws and Pitfalls Patch Recommendation 8

This is just a quick alert blog post for Friday with an OPatch Alert: Be aware of cleanup issues – and the JDK version. And thanks to several people who either commented or mailed me directly and asked if I could alert others as well.

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OPatch cleanup issue

At first, you may have read earlier this week my article about patching my environments with the April 2020 bundle patches. For my patch activity, I’ve had to exchange my OPatch versions for 11.2.0.4, 12.2.0.1 and 19.7.0. And I guess, I would have had …

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.

Photo by Moritz Schmidt on Unsplash

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

Issues with seed databases, patch bundles and OJVM in 19c

Posted on February 18, 2020 by Mike.Dietrich Flaws and Pitfalls JVM 11

I really rely on people telling me about issues they saw. And in this case, it happened twice within a few days. At OOW London, a customer came after my talk and told me about invalid objects and an incredible long recompilation time. In fact, he had to apply an OJVM patch in order to solve this. When I returned home, Jure commented on the blog about a very similar issue. I spent some time on the weekend to check it out. And I realized: There are issues with prebuilt seed databases and OJVM in 19c.

Issues with seed databases, patch bundles and OJVM in 19c

Photo by Max

APEX is invalid after upgrading to 12.2 – ORA-20001

Posted on February 11, 2020 by Mike.Dietrich APEX Flaws and Pitfalls 0

We are running the AutoUpgrade-for-RAC beta test since last week. And the first issue one customer encountered … is neither an AutoUpgrade nor a RAC issue. It has to do with APEX and SPATIAL, and missing grants. APEX is invalid after upgrading to 12.2 – ORA-20001

APEX is invalid after upgrading to 12.2 - ORA-20001

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What is happening?

You are doing an upgrade to Oracle Database 12.2.0.1. And you receive a number of errors during the component validation phase.

19:04:14 SQL> EXECUTE dbms_registry_sys.validate_components;
...(19:04:15) Starting validate_apex for APEX_180100
ORA-20001: MISSING GRANT: grant execute on "MDSYS"."SDO_DIM_ARRAY" to APEX_180100
ORA-20001: MISSING GRANT: grant execute on

GI Patch 28553832 may be needed before you upgrade to 19c

Posted on January 7, 2020 by Mike.Dietrich ASM / RAC / GI Flaws and Pitfalls 8

Thanks to my colleague Sebastian Alasino who works in the MAA team out of the UK. Sebas highlighted this issue to. And I’d like to share it with you when you attempt to upgrade Grid Infrastructure to Oracle 19c. If you have the Docker RPM installed and you were lazy on patching, then GI Patch 28553832 may be needed before you upgrade to 19c.

GI Patch 28553832 may be needed before you upgrade to 19c

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What is the issue?

If the Docker Engine RPM is installed and your GI version is 12.1.0.2, 12.2.0.1 or 18c below a certain patch level, the CSSD demon fails to …

ORA-1722 when upgrading to 19.4.0 or 19.5.0 on Windows

Posted on December 18, 2019 by Mike.Dietrich Flaws and Pitfalls 17

Oh boy – I try to avoid blogging about errors on a specific platform. But as this topic was brought to my attention now 3x in 2 weeks, I think I’ll send it out. And I hope you won’t hit this ORA-1722 when upgrading to 19.4.0 or 19.5.0 on Windows.

ORA-1722 when upgrading to 19.4.0 or 19.5.0 on Windows

What is failing?

The database upgrade only on the MS Windows platform fails when you attempt to upgrade to 19.4.0 or 19.5.0. This means, you downloaded and installed 19.3.0. And then you followed our advice and applied one of the most recent Release Update – ideally 19.5.0, the October …

Database Migration from non-CDB to PDB – Various Pitfalls

Posted on August 2, 2019 by Mike.Dietrich Flaws and Pitfalls Single-/Multitenant 22

There are several pitfalls when you plugin a non-CDB into a CDB environment. I’d like to highlight some of them – and show you potential workarounds as well. This is part of a series of blog posts to make your migration from non-CDB to PDB a bit smoother.

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Database Migration from non-CDB to PDB – Various Pitfalls

In all the previous blog posts of this series I tried to explain specific pitfalls, and how you can workaround them. This article is meant to collect the “leftovers”, the minor issues and pitfalls which you may not …

Database Migration from non-CDB to PDB – The Patch Level Pitfall

Posted on August 1, 2019 by Mike.Dietrich Flaws and Pitfalls Single-/Multitenant 0

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Database Migration from non-CDB to PDB – The Patch Level Pitfall

When you consolidate on a larger scale, it is very likely that you have different patch levels in your database environments. But when you attempt to plugin a non-CDB into a CDB, you may see …

Database Migration from non-CDB to PDB – The Component Pitfall

Posted on July 31, 2019 by Mike.Dietrich Flaws and Pitfalls Single-/Multitenant 6

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The Component Pitfall

With component we mean the database component which you can find in DBA_REGISTRY – or CDB_REGISTRY. When Multitenant became available over 5 years ago, a decision had been made to make all options/components mandatory in a container database. This decision had to …

Database Migration from non-CDB to PDB – The Time Zone Pitfall

Posted on July 30, 2019 by Mike.Dietrich Flaws and Pitfalls Single-/Multitenant 0

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Database Migration from non-CDB to PDB – The Time Zone Pitfall

Interestingly, there is no issue with different time zone settings within a single CDB. Your CDB$ROOT can be on DST V.32 whereas a PDB you plugin can be already on DST V.33. But only …

Database Migration from non-CDB to PDB – The COMPATIBLE pitfall

Posted on July 29, 2019 by Mike.Dietrich Flaws and Pitfalls Single-/Multitenant 0

Database Migration from non-CDB to PDB - The COMPATIBLE pitfall

Database Migration from non-CDB to PDB – The COMPATIBLE pitfall

When you migrate your non-CDB to PDB, in most cases the COMPATIBLE setting of the non-CDB will be lower than the setting of the receiving CDB. But still in this case you may see warnings. I will explain how to deal with …

Database Migration from non-CDB to PDB – Typical Plugin Issues and Workarounds

Posted on July 29, 2019 by Mike.Dietrich Flaws and Pitfalls Single-/Multitenant 0

In the previous blog posts I showed different approaches on how to migrate your database on a same Endianness platform into Multitenant. Whether you prefer to upgrade first or plugin first is up to you. I recommend upgrading first as this allows you a seamless fallback. But regardless of which approach you prefer, you may take care on potential pitfalls. Hence, this blog post is about Database Migration from non-CDB to PDB – Typical Plugin Issues and Workarounds. It may not be complete when I publish it and I may extend it later on. Let me know if you have …

In case you miss DBMS_OPTIM_BUNDLE … again …?!?

Posted on June 6, 2019 by Mike.Dietrich Flaws and Pitfalls 12

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I’m tempted to copy and paste my blog post about DBMS_OPTIM_BUNDLE from February 2019, and exchange only 12.2.0.1 with 19c. But in this case the root cause is different. So this blog post is meant for Oracle 19.3.0 to be precise – in case you miss DBMS_OPTIM_BUNDLE … again … ?!?

Information about DBMS_OPTIM_BUNDLE

You will find a lot of information about DBMS_OPTIM_BUNDLE, what it does, since which release it exists and much more in these blog posts:

In case you are missing DBMS_OPTIM_BUNDLE (Feb 11, 2019)
DBMS_OPTIM_BUNDLE Package in Oracle 12.2

Data Pump: The Time Zone Pitfalls

Posted on May 14, 2019 by Mike.Dietrich Flaws and Pitfalls 13

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Last week a very experienced colleague called me. He had issues with an export dump taken from an Oracle 20c database importing into 19c. It failed. So this blog post is about Data Pump: The Time Zone Pitfalls.

The Case

Usually you will see this issue only when you try to export from a higher version, and then attempt to import into a lower one. But the same thing can happen when you patched your databases partially with a newer time zone patch regardless of the version.

My colleague saw this error:

impdp system/welcome1@//localhost:1521/MYDB

You MUST patch 12.1.0.1 and 11.2.0.3 and older databases before June 2019

Posted on February 25, 2019 by Mike.Dietrich Flaws and Pitfalls 18

First of all, this blog post is not new. I blogged about this SCN topic a while ago already. But some of you seem to operate still older databases for various reasons. And even if you think that you are safe, double check for any older databases in your environments. You MUST patch 12.1.0.1 and 11.2.0.3 and older databases before June 23, 2019. And just to be clear: June 23, 2019 is going to happen in less than 4 months.

You MUST patch 12.1.0.1 and 11.2.0.3 and older databases before June 2019

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Who is NOT affected?

If you use the following Oracle database releases …

In case you miss DBMS_OPTIM_BUNDLE in 12.2

Posted on February 11, 2019 by Mike.Dietrich Flaws and Pitfalls 0

Strange things happen sometimes. I got alerted by a customer before Christmas about package DBMS_OPTIM_BUNDLE missing after applying a Release Update. I’ve had a conversation with Nigel Bayliss, the Optimizer PM – but Nigel hasn’t heard of such things either. We both investigated but couldn’t reproduce the issue. But after the end-of-the-year holidays I received similar messages from other customers. In case you miss DBMS_OPTIM_BUNDLE in 12.2, then this blog post should help you.

In case you miss DBMS_OPTIM_BUNDLE in 12.2

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What is DBMS_OPTIM_BUNDLE?

I blogged about this package in the past already several times:

Fixes for Adaptive Features are included

Conventional INSERTs into HCC tables may be slower since Oracle 12.2

Posted on November 28, 2018 by Mike.Dietrich Flaws and Pitfalls 2

I work with several customers at the moment on their Oracle 12.2/18c “go live” projects. And one of these customers encountered a strange issue when comparing Oracle 11.2.0.4 to Oracle 12.2.0.1/18.3.0: Conventional INSERTs into HCC tables may be slower since Oracle 12.2. Actually in this particular case, significantly slower. Read below why this can happen and how the workarounds look like.

Hybrid Columnar Compression

There’s a lot of material to read and study about Hybrid Columnar Compression (HCC). With HCC we store the same column for a group of rows together. The data block does not store data in row-major …

Where does the database link SYS_HUB come from?

Posted on September 24, 2018 by Mike.Dietrich ASM / RAC / GI Flaws and Pitfalls 6

This blog lives a lot from customer’s feedback and updates. And these days, Nicolas Jardot from dbi-services in Switzerland sent me an email asking: Where does the database link SYS_HUB come from? And if he can delete it or if it has any deeper purpose. Neither Google nor MOS reveal a lot of useful information

Where does the database link SYS_HUB come from?

I took my vanilla 18.3.0 database in our hands-on lab and check:

column owner format a5
column db_link format a12
column username format a12
column host format a12

select con_id, owner, db_link, username, host from cdb_db_links;

    CON_ID

RMAN Backup Gives RMAN-06091: No Channel Allocated for Maintenance

Posted on August 21, 2018 by Mike.Dietrich Flaws and Pitfalls RMAN 17

RMAN Backup Gives RMAN-06091: No Channel Allocated for Maintenance I really don’t want to turn this blog into an accumulation of issues and flaws. But as I explained many times before, the blog for me is also a way to dump information I likely will need the sooner or later again.

Recently I blogged about another RMAN issue in Oracle 12.2.0.1 with traces. This was fixed with the July 2018 RU for Oracle 12.2.0.1. But the issue below about which Piero Ferraz from Brazil alerted me (thanks!!!), happens in exactly this RU.

RMAN Backup Gives RMAN-06091: No Channel Allocated for Maintenance

This issue gets introduced with the July …

Cloning with Pluggable Databases in Oracle 18c

Posted on August 16, 2018 by Mike.Dietrich Flaws and Pitfalls Single-/Multitenant 8

We had several discussions on the internal mailing lists the other day about cloning with Pluggable Databases in Oracle 18c (or 12.2.0.1). And I blogged about this topic a while ago but realized I may need to refresh this a bit.

Cloning with Pluggable Databases in Oracle 18c

My example from the old blog post still works fine. But I realized that I switched my database into read-only mode. Hence, I like to repeat it and check different options.

Cloning a 12.1 PDB into Oracle 18c

In the source CDB1 I create a fresh PDB first, then open it and create a cloning user with the necessary …

Flaws and Pitfalls

What is the MGA?

Partial Offline Backup Strategy?

What is the issue?

It’s a bit tricky

OPatch cleanup issue

What happens?

What is happening?

What is the issue?

What is failing?

Database Migration from non-CDB to PDB – Various Pitfalls

Database Migration from non-CDB to PDB – The Patch Level Pitfall

The Component Pitfall

Database Migration from non-CDB to PDB – The Time Zone Pitfall

Database Migration from non-CDB to PDB – The COMPATIBLE pitfall

Information about DBMS_OPTIM_BUNDLE

The Case

Who is NOT affected?

What is DBMS_OPTIM_BUNDLE?

Hybrid Columnar Compression

Where does the database link SYS_HUB come from?

RMAN Backup Gives RMAN-06091: No Channel Allocated for Maintenance

Cloning a 12.1 PDB into Oracle 18c

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