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May 2017

The village idiot

If you are not familiar with the term Village Idiot, then Wikipedia provides a sufficient definition from which I can base this blog post.

“The village idiot … is a person known for ignorance or stupidity”

Over the past couple of weeks I’ve been flying a bit.  First was OpenWorld and OracleCode in New Delhi in India, and from there, I was heading straight from there to Cleveland, Ohio for the GLOC users conference for the first time.  Being a fairly seasoned traveller, this should have been a relatively straightforward affair.

Well… things didn’t turn out that way. 

255 columns

This is one of my “black hole” articles – I drafted it six months ago, but forgot to publish it.

Pesentations at Great Lakes Oracle Conference 2017

For those who came to my sessions at GLOC 2017 in Cleveland, thank you for giving me your time. I hope you found them useful. As always, I love to hear your feedback. You can add a comment here, email me at, tweet at @ArupNanda or at

All about Deadlocks The Presentation The Tracefile Used as an Example
How Buffer Cache Works The Presentation The Scripts
Big Data for Oracle DBAs The Presentation

Again, appreciate your coming to my session and thanks in advance for your feedback.

random “ORA-01017: invalid username/password” in 12cR2

Since 12cR2 is out, we give our 12c new feature workshop with hands-on exercises on 12.1 and 12.2 releases. When I gave it last month, I had a small problem when doing demos: sometimes the connections as sysdba failed with “ORA-01017: invalid username/password”. It was at random, about one every 5 login attempts and I was sure that the password did not change. As I give another of this training next week, I tried to reproduce and fix this issue and finally found out that the problem was really random: dependent on the entropy when reading /dev/random

12.2 new features: a first encounter with the new Cluster Health Advisor

One of the many new manuals that showed up in Oracle Database 12.2 is the Oracle Autonomous Health Framework User’s Guide. This book contains a lot of information, some of which we already know from previous releases, and some new stuff as well. One of the new chapters caught my eye in particular:

“Proactively Detecting and Diagnosing Performance Issues for Oracle RAC”

Said chapter 5 introduces a new feature, called the Cluster Health Advisor (CHA), that should help you understand the performance of your cluster better. Really? Time to start the VMs to create a test.

Where in the World is Goth Girl- Week 20, 2017

After looking at my upcoming schedule for 2017, I realized that I need to start posting on where and what conference(s) I’m at regularly.

With that realization, I present “Where in the World is Goth Girl” posts that will help keep track of me, (before my husband has a homing device surgically implanted in my brain….:))

12cR2 Cross-container DML – insert into container()

Multitenant has been introduced in with the goal to share resources but isolate data. However, having all PDBs in the same root may be convenient to manipulate data in multiple PDBs. In the first patchset,, a way to query cross-container has been introduced for the CDB administrator to see data in other containers. In the second release,, this goes further with the introduction of Application Containers and cross-PDB DML. Currently, not all possibilities are documented and not all documented features are actually working. This will probably improve in next patchset. I’ll start here with something simple: insert from root into a table which is in a PDB.

Ara: ansible run analysis

This is a short blogpost meant as both an introduction for those who don’t know Ara and a guide on how to install Ara.
Ara means ‘Ansible Runtime Analysis’, and is a tool for storing metadata that Ansible uses during execution. It is very valuable, because it takes a lot of guesswork and entering debug statements in your playbook away.

This is a guide on how to install Ara on Oracle Linux 7. I assume ansible is already installed. If want to start fresh, add EPEL and yum install ansible and git. That’s all you need to begin!

First, become root and install ara using a playbook:

Bushy Joins – a closer look

When 12.2 came out most of the (optimizer) focus was around SPD and how to avoid the challenges from 12.1. Still 12.2 introduced several (less acclaimed) optimizations including “Bushy Join” transformation, which is interesting since (I think, corrections welcome) Bushy Join concept isn’t necessarily tied to query transformation in general, especially before 12.2 (some reference about “manual” bushy joins here and here) or in other RDBMS (a manual example on SQL Server here).
Anyway being the CBO way of improving our code query transformations here we go again.

Insider View of a Delphix VDB Rewind

I love questions-  They give me something to write about that I don’t have to come up with from my experience or challenges…:)

So in my last post, Paul asked:

I am not sure what happens to the other changes which happened while the release was happening? Presumably they are also lost? Presumably the database has to go down while the data is reverted?

The Setup

In our scenario to answer this question, I’m going to perform the following on the VEmp_826 virtualized database: