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March 2008

The beginning of Oracle Denmark

I started working for a bank called Sparekassen SDS 1st of January 1987. They had just bought Oracle, and that's how I ended up in the database world.

In 1990 I joined Oracle Denmark's support organisation under the magnificient leadership of Jannik Ohl.

He was fired by Peter Perregaard in 1998 or so, because they didn't like each other. Until then things were fantastic. After that things were not.

Jannik was replaced by Allan Marker, who was not nearly his equal in any which way you choose to look. Especially when it comes to the art of thinking instead of wondering how you can survive in the corporate culture for the next few months.

But that's how things are. Peter made a mistake, and he regrets it to this day, I'm sure (as in: sure).

So Jannik went into geo-stationary orbit. In other words: He joined the Oracle EMEA organisation (Europe, Middle East, Africa).

The Value of Information

There has been an interesting and somewhat heated discussion going on about a recent blog post by Dominic Brooks and referenced by Doug Burns about the relative value of data vs. applications.  Actually, most of the heat seems to be directed at a comment made by Tim Gorman on several mailing lists in which he states that:

Data, not programs, is the only thing that matters — applications are transient and have no value except to acquire, manipulate, and display data. Data is the only thing with value.

I’ve deliberately taken the quote out of context — for that is how it’s being reacted to, fairly or unfairly on Doug Burns’ blog entry.

I’m not actually going to add any fuel to that fire, only offer up some observations.  I think I agree with many who are stating that data that lies about, unexploited by any application, is a pretty useless waste of storage.  That the true value of data comes from an ability to use it through an application which allows one to analyze, manipulate and visualize information synthesized from the data soup.  One reason I’m excited about the new company I’m with is its focus on helping people increase their ability to exploit their data.

A Day On The Road (To Hell)

My ringtone on my mobile is currently Highway To Hell with AC/DC, but I thought Chris Rea's The Road to Hell was more appropriate as a title today. I hope you'll understand why after reading this.

I've just come home from 10 days in a Danish town called Horsens doing a reality TV show called "The Secret Millionaire", which has run for two seasons in England.

Now they've done 11 programs in Denmark. Mine will probably be shown in the fall of this year.

Basically, a TV crew of three followed me all day long while I (complete with a cover story) visited places where good souls help out people in need. At night I stayed in a borrowed, Turkish immigrant apartment.

At the end of the 10 days I put on one of my Armani suits and told the good people that in fact I was not that much down and out, and that I'd like to donate some of my own money to their cause (a total of 250.000 Danish kroner, to be exact).

Pl/sql function result cache in 11g

Oracle provides a cross-session cache for user-defined PL/SQL function results. January 2008 (updated June 2010)

The Rule of 5

During my 2006 Hotsos presentation I mentioned 2 “rules of 5″ that I like to use — I didn’t come up with them myself, but I’m pleasantly surprised when I find evidence to support them.  Of course, the human brain always finds evidence to support it’s own prejudiced hypotheses (for an excellent read that demonstrates this concept, try Focault’s Pendulum by Umberto Eco).  Anyway, the 2 rules of 5 are:

  1. Most people have 5 times as much hardware as they need (Tom Kyte)
  2. A useful tuning goal for SQL is 5 LIOs per row per row source (Cary Millsap)

Of course, you need to know what LIOs are — a depressingly larger and larger number of DBAs I meet don’t have the foggiest notion of them.

I point you at an excellent blog post by Shakir Sadikali at the Pythian Group which shows off a ten-node RAC cluster brought to its knees by unindexed foreign keys (doh!).  Fixing that and other tuning operations has allowed them to reduce the cluster down from 10 nodes to 2 nodes (or, 1/5th their original hardware).  Score one for #1!

BTW, most people argue #2 by talking to me about aggregates.  My standard response is that any aggregate that is queried heavily is an opportunity for derivation, pre-calculation or optimization.

2008 Hotsos Conference Material

I’ve uploaded my presentation and the DDL code generation scripts I referenced in my talk.  Just scroll down on the right hand side of this blog to the section marked “Content”.

Native dynamic sql optimisation in 10g

Native dynamic SQL gets an optimisation to match DBMS_SQL for efficiency. June 2004

Flashback version query in oracle 10g

We can now view the evolution of our data with flashback version query. August 2005