Wrong Result Bug using group-by placement optimization

Last week I’ve mentioned on Twitter that we ran into wrong result bug. We found workaround quickly but I’ve decided to spend some time to reproduce error and write blog post to warn you about this optimizer behavior.
Special thanks to my colleague who spotted odd results which led us to this finding.

My test (virtual) environment is:
OS: Oracle Enterprise Linux 5.8
DB: Oracle EE

In test I (more...)

Oracle Scheduler External Jobs and Credentials

A few months ago I wrote a blog post - Kill stuck Oracle process from OS using DBMS_SCHEDULER? We had some problems with stuck Oracle processes and I have created external job to kill stuck processes for a quick workaround.

At the end of that post I wrote:
When dbms_scheduler (more...)

RMAN Duplicate from Active Database – ASM to non-ASM

In this post I want to explain how to create duplicate database from active 11gR2 database using RMAN. There are many blog posts covering that subject but most of them are covering non-ASM to non-ASM, ASM to ASM or non-ASM to ASM duplications.
I want to cover ASM to non-ASM (more...)

RMAN PITR – testing some scenarios

I am regular follower of Oracle-l mailing list which is great source of knowledge for Oracle experts. Two days ago one Oracle DBA posted question “RMAN restore/recover problem” which induced me to re-check my knowledge about some RMAN PITR scenarios.

So I’ve performed some tests and decided to (more...)

How to detach storage device from running virtual machine in VirtualBox

In this post I want to show how to test what will happen with your cluster if you simply detach shared storage device from it. VirtualBox is great tool for that purpose because you can test such scenario without involving many people or causing any damage.

I am aware that (more...)