Slow

Upgrade to 26ai may hang due to block checking events

This issue is caused by an internal change, and we hit this now with two very large customer upgrades recently. Therefore, I would like to point to a fix, a workaround and the following RU in case you see your Upgrade to 26ai may hang due to block checking events.

Upgrade to 26ai may hang due to block checking events

Photo by Nareeta Martin on Unsplash

What would you see?

This issue can happen with cloning, PDB refreshable clones or just a copy or restore of your database for the subsequent upgrade to Oracle AI Database 26ai. It is not dependent on AutoUpgrade but since AutoUpgrade is the only …

Queries on dictionary tables are slow in Oracle Multitenant?

Posted on February 10, 2025 by Mike.Dietrich Flaws and Pitfalls Single-/Multitenant 12

I love to learn something new every day. And on Friday afternoon last week I learned something new again. It started (as often) with a very simple question from a colleague working from the Oracle Malaga office in Spain. The customer has an issues with some queries being slower than before once they moved from on-prem to the cloud into a PDB. But are queries on dictionary tables are slow in Oracle Multitenant generally?

Queries on dictionary tables are slow in Oracle Multitenant?

Photo by Pascal van de Vendel on Unsplash

What was the case?

The customer ran some queries against dictionary views in the PDB in Oracle Database …

Binary patching is slow because of the inventory

Posted on May 10, 2022 by Mike.Dietrich Patch Recommendation 57

The headline of this blog post may sound a bit cryptic: Binary patching is slow because of the inventory. But actually this seems to be one of the main causes when your binary patching gets slower and slower with every patch you apply.

Photo by Valdemaras D. on Unsplash

The more you patch, the worse it gets

Well, this is a tough headline. But you may have read my blog posts about my quarterly patching experience. It actually started with the July 2021 RU in my 19c environment when I wrote:

At least in my environment, both checks with the

How to speed up your database and GI patching

Posted on May 9, 2022 by Mike.Dietrich Patch Recommendation 12

Several of you mailed me already and commented. And I know that I promised this blog post for weeks, if not longer. So let me try to explain How to speed up your database and GI patching. Since this blog post has a longer history, I’d say far over 6 months, it will be a bit longer than the usual posts. At when I started writing it, I decided to split it up into several pieces to make it more digestible but also to allow easier finding of certain topics. I hope it may help easing some recent patching …

Speed up Upgrade Phase 65 with a new catuposb.sql

Posted on July 5, 2016 by Mike.Dietrich Flaws and Pitfalls Upgrade / Migration 10

Credits to Chris Smids from Proximus in Belgium 🙂 Thanks, Chris!!!

Upgrade to Oracle 12.1.0.2 is slow in phase: #65 ?

You are wondering why phase: #65 of the database upgrade to Oracle Database 12.1.0.2 takes quite a while. You dig down into the catupgrd0.log and recognized this statement taking a while:

dbms_output.put_line('catuposb, update 4 - rows updated ' || rows_updated);
END; -- end of update for system internally generated objs
/

The cause for this issue is buried in the script catuposb.sql hitting stale histograms which did not get refreshed even if you gathered dictionary stats before the upgrade …

Query on ALL_SYNONYMS is slow in Oracle Database 12c

Posted on December 22, 2015 by Mike.Dietrich Flaws and Pitfalls Oracle Database 12c Performance Tuning 5

A customer (Thanks Stefano!) alerted me on this issue during a workshop and I did some further investigation. Basic headline is:

Query on ALL_SYNONYMS is very slow in Oracle Database 12.1.0.2 compared to 11g.

The workaround for this 21324443: SLOW QUERY IN 12C ON ALL_SYNONYMS. is:

dbms_stats.gather_table_stats('SYS','OBJ$',estimate_percent
=>100, method_opt => 'for columns flags size 1, spare3 size 254, type# size 254');

and I see that at least 8 other customers opened SRs hitting the same issue.
Does the workaround suit you in any way?

The bug had no progress since it was opened. If you are seeking progress …

Slow

Upgrade to 26ai may hang due to block checking events

What would you see?

Binary patching is slow because of the inventory

The more you patch, the worse it gets

How to speed up your database and GI patching

Speed up Upgrade Phase 65 with a new catuposb.sql

Upgrade to Oracle 12.1.0.2 is slow in phase: #65 ?

Query on ALL_SYNONYMS is slow in Oracle Database 12c

Query on ALL_SYNONYMS is very slow in Oracle Database 12.1.0.2 compared to 11g.

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