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March 2012

Best practices? I'm not so sure.

I'll be delivering a webinar this week that has the words "Best Practices" in the presentation title. As I've been preparing, it has really struck me how my definition of a best practice is not the traditional IT definition. Wikipedia says


Here’s a wonderful lesson from Cary Millsap – be very careful if you ever want to sell him anything – that reminded me of a Powerpoint slide I had produced for a presentation a few years ago. It took me a little time to track it down but I finally found the slide, reproduced below, in a presentation called: “The Burden of Proof” that I had given for the Ann Arbor Oracle User Group in 2002. (The picture of the Earth is the Apollo 17 image from NASA):

Quiz Night

I know I haven’t been very good about posting on the blog or replying to questions lately (and a big thank you to anyone who has answered some of the recent questions correctly), but tonight is a Friday night, and I have a few moments to spare, so here’s a question prompted by a recent comment on OTN.

I have a table declared as follows (and the ellipsis means repeat the column definitions according to the simplest and most obvious pattern to give you 1,000 columns all of type number(1)):

create table t1 (
        col000  number(1),
        col001  number(1),
        col002  number(1),
        col997  number(1),
        col998  number(1),
        col999  number(1),
        constraint t1_pk primary key (col000)

I have one row in the table.

How many row pieces might that row consist of ?

The new oracle-validated is here (oracle-rdbms-server-11gR2-preinstall)…

Lenz Grimmer blogged today about the release of the “oracle-rdbms-server-11gR2-preinstall” package, the Oracle Linux 6 version of the “oracle-validated” package we know and love.

I did a run through of an installation using it and it does exactly what it says it will. I’ve modified my 11gR2 installation on OL6 article accordingly.



Friday Philosophy – The Abuse of Favours

You probably all recognise this situation:

Dave needs something doing that he can’t do himself – let’s say it is creating an API for the file management package. It isn’t your job to do but it is something you can do. Dave is blocked until the API is created.

So, being a nice person, you tell Dave you will see what you can do for him over the next couple of days.

So why is it that what Dave hears is “Dave, I love you more than life itself, I am dedicated to this task and I WILL complete it before the end of tomorrow. My other tasks, emergency production issues and the untimely demise of my cat are all secondary to this endeavour.”.

You see, 24 hours later, Dave is at your desk “When will this be done?! I’m blocked until I get this!!!”. If he’s the guy I had recently his next step is to slap his fist into his palm as he utters, almost shouts “I NEED this!”.

The String Puzzle

I gave my two boys an old puzzle to solve yesterday. I told them that I’d give them each $10 if they could solve it for me. It’s one of the ways we do the “allowance” thing around the house sometimes.

Here’s the puzzle. A piece of string is stretched tightly around the Earth along its equator. Imagine that this string along the equator forms a perfect circle, and imagine that to reach around that perfect circle, the string has to be exactly 25,000 miles long. Now imagine that you wanted to suspend this string 4 inches above the surface of the Earth, all the way around it. How much longer would the string have to be do do this?

How often are you backing up your cloud services?

I tend to self host as much as possible, so the emphasis is always on me to keep on top of my backups. Like most DBAs, I’m a bit of a control freak, so relying on myself suits me. Having said that, there are some services I delegate to the cloud (mail, contacts, calendar). Yesterday I was thinking about how bummed out I would be if any of these services lost my data and I suddenly got the fear. This morning I’ve had a backup frenzy. The following notes from Google give suggestions for backing up mail, contacts and calendar entries.

I’m a [ Chrome | Firefox | Opera ] user…

Over the last few months my browser usage switched from pure Chrome to a combination of Chrome, Firefox and Opera, all running on Fedora 16 (x86-64). This may sound a little odd, but when you see what I use them for it may not sound so wacky.

(Virtual) Public Appearances - Free Webinars

I'll be presenting at two upcoming webinars:

1. "Oracle Cost-Based Optimizer Basics" hosted by on Wednesday, 11th April 2012 16:00 (UK Time).

In this session I'll explain the key concepts that influence the decisions of the Oracle Cost-Based Optimizer most. If you want to understand the key concepts about how to write efficient queries and why the optimizer sometimes might not come up with a reasonable execution plan, then this session is for you.

Note that the webinar is free and registrants will receive a recording afterwards. Here is the link to the official landing page. Thanks to for hosting this session.

Here is an abstract of the session:


March 28, 2012 A recent question on the OTN forums asked which PLAN_HASH_VALUE appears in V$SQLAREA when there are multiple child cursors for a single SQL_ID value, when some child cursors have a different execution plan.  Certainly, this bit of information must be in the Oracle Database documentation.  Let’s check the V$SQLAREA documentation for Oracle Database 11.2: [...]