Corruption

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

Posted on June 22, 2020 by 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.

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

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MOS Note:136697.1 – New HCHECK.SQL for Oracle Database 12c

Posted on May 19, 2016 by Flaws and Pitfalls RMAN 0

A while back we added this slide to our big slide deck:

The story behind this slide

A large and important customer in the US tested a patch set upgrade – but when they approached the production upgrade from 11.2.0.2 to 11.2.0.3 on a large RAC cluster they’ve had to cancel the attempt and revert to the previous state.

Reason

They’ve hit a dictionary corruption somewhere silently sleeping in the database causing no trouble at all so far – until the upgrade touched the broken structures

They’ve asked us:
“How could we ensure the database is really healthy and …

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Ouch, this hurts: bug 21923026 – patch Oracle 12c Home before upgrading if you have OLTP Compression in 11g

Posted on November 2, 2015 by Flaws and Pitfalls Oracle Database 12c Patch Recommendation 1

Patch

Actually I’d consider this as a real serious issue which may affect many customers with larger deployments using the Advanced Compression Option’s OLTP Compression.

I came across it as Don Seiler full of anger twittered some bad words about Oracle Database 12.1.0.2.. We’ve exchanged a good number of emails – and I could see the issues Don and his colleagues got while assisting a customer to go live on Oracle Database 12c.

The most interesting one happened on the physical standby after the primary got upgraded. The MRP failed with an ORA-600.

Issue

After upgrading from Oracle 11.2.0.3 to …

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Ouch, this hurts: bug 20880215 – patch Oracle 12c

Posted on October 16, 2015 by Flaws and Pitfalls Oracle Database 12c Patch Recommendation 3

Patch

Just realized that my preivous blog post heading was misleading: it said “patch AFTER upgrade” which is misleading. You should apply this patch BEFORE you upgrade but of course to your new/future Oracle 12c home. If you hit the issue then apply the patch after upgrading to remedy it. Sorry for the confusion.

No updates for over a week? Sorry for that but too many workshops, swamped with OOW prep work – and a wonderful issue with the browser cache and the blog software putting all my new blog post work directly into /dev/null.

Thanks to Marcel Paul for …

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Ouch, this hurts: bug 17325413 – patch BEFORE upgrade!

Posted on August 18, 2015 by Flaws and Pitfalls Oracle Database 11g Patch Recommendation Upgrade / Migration 15

PatchI really don’t want to turn this blog into something making our database look bad. But in this case it is really necessary as it is VERY UNUSUAL that we recommend to patch the database BEFORE upgrade.

Just for clarification:

The following topic will affect all databases between 11.1.0.6 and 11.2.0.4.1 – those (and only those) need to be patched BEFORE upgrade. The topic is fixed in 12.1.0.2 but as it gets introduced with the BEFORE upgrade database version you’ll have to apply the fix before upgrade. The inclusion of the fix in 12.1.0.2 means only that the …

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Log Writer Slave Issues in 12.1.0.2 – mainly on IBM AIX and HP-UX but also on Linux

Posted on July 1, 2015 by Flaws and Pitfalls Oracle Database 12c Parameters 10

Currently we see a lot of issues with the Multiple Logwriter feature in Oracle Database 12.1.0.2, especially on the IBM AIX platform.

What are Multiple LGWRs?

You will see multiple LGnn (Log Writer Worker) processes on multiprocessor systems, The LGWR (Log Writer) creates worker processes (slaves) to improve the performance of writing to the redo log. LGnn (Log Writer Worker) processes are not used when there is a SYNC standby destination. Possible processes include LG00–LG99.

Here is a list of new background processes in Oracle Database 12.1:
MOS Note 1625912.1 – New Background …

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Mike Dietrich
Oracle Senior Director of Product Management for Database Upgrade, Migrations and Patching writing just another blog.

Opinions certainly are my own as is this page.

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