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March 2016

The death of the demo script

On AskTom, one of the things we always strive to do is provide demo scripts in our answers where appropriate.  That way, people can see our line of thought, and hopefully get an understanding as to how we arrived at a solution.  And there’s two very important concepts in that last sentence:

  • our line of thought
  • how we arrived

The demo script itself, is a representation of that, not necessarily a cast iron guarantee that you should be cut/pasting it into your Production system!  If you are honestly expecting that a demo script that we run, will be exactly how it will run on your system, you’re perhaps being a little naive. 

Why ?

Adding a Database to the Raspberry Pi Zero

This morning, after someone added SQL Developer to a Raspberry Pi 3, Jeff Smith pinged me and the question was posed, as it often is, can you run Oracle database server on a Raspberry Pi, (RPI)?

Video : The MERGE Statement

After a what seems like an eternity of being ill and having a dodgy throat, followed quickly by a couple of conferences, I’ve finally got back on the horse and recorded another video.

I was explaining a specific aspect of the MERGE statement to one of my colleagues and while I was doing it I was thinking, “Have I done a video on MERGE yet?” Now I have.

The cameo for this video is Cary Millsap. If you watch the out-takes at the end you will see the level of respect and trust I have garnered in the community. The words confused and suspicious spring to mind! :)

Introducing TUNAs360 – Tuning with Active Sessions without Diagnostic Pack


I’m happy to introduce a new free tool that allows to get initial insights about a database using eDB360/SQLd360 like charts without Diagnostic Pack!!!

(TUN)ing with (A)ctive (s)essions, aka TUNAs360, requires no installation and no parameter when executed; it observes the workload for few minutes and then collects a set of reports on such load.

The idea behind the tool is to help getting started in those situations where there is a concern with database performance but the reason is unknown, the classic “the database is slow but I don’t know why”.
In case further investigation is necessary then eDB360 or SQLd360 can be leveraged.

Once executed TUNAs360 provides several reports for the whole database (cluster and node specific) plus additional reports to help drill into the details of the top 5 sessions and top 5 SQLs during the time the load was observed.

Retaining Previous Agent Images, the Why and the How

I appreciate killing two birds with one stone.  I’m all about efficiency and if I can satisfy more than one task with a simple, productive process, then I’m going to do it.  Today, I’m about to:

DB2 fully supported on Delphix

I’ve received a number of inquiries lately about the support of DB2 on Delphix and yes, Delphix 5.0 now supports full automation of virtual data for DB2. With the addition of DB2, Delphix now supports full automation of virtual data on all three of the major enterprise databases

  • Oracle
  • SQL Server
  • DB2

as well as Sybase, MySQL and Postgres.

For more information on DB2 in Delphix 5.0 see

and here is a video demoing DB2 on Delphix 5.o

Index Speculation

There’s a current question on the OTN database forum as follows (with a little cosmetic adjustment):

I have a request for 3 indices as shown below. Does the 1st index suffice for 2 and 3?  Do I need all 3?

  • create index idx_atm_em_eff_ver_current_del on atm_xxx_salary (employee_key, effective_dt, salary_version_number, is_current, is_deleted);
  • create index idx_atm_em_ver_current on atm_xxx_salary (employee_key, salary_version_number, is_current);
  • create index .idx_atm_sal_current_del on atm_xxx_salary (employee_key, is_deleted, is_current);

In the absence of any information about the data and the application the correct answer is: “How could we possibly tell?”

Collaborate 16: My sessions

I’ll be at Collaborate 16 next month and looking forward to seeing lots of good friends, learning some new things, and sharing a little experience too. For the last of those, I’ll present 3 sessions, er, more like 2.2 sessions:

Adding GPIO Pins to the Raspberry Pi Zero

Although the Raspberry Pi 3 is now available, many people are still interested in it’s cheaper, smaller version, the Raspberry Pi Zero.


A posting on the OTN database forum a few days ago demonstrated an important problem with hinting – especially (though it didn’t come up in the thread)  in the face of upgrades. A simple query needed a couple of hints to produce the correct plan, but a slight change to the query seemed to result in Oracle ignoring the hints. The optimizer doesn’t ignore hints, of course, but there are many reasons why it might have appeared to so I created a little demonstration of the problem – starting with the following data set: