Same mistake, three different errors…

Funny thing I had today. Well funny, not when you want to make progress in your work, but still interesting what I discovered when I tried to isolate the problem…I found a way to make the same mistake and have Oracle return three different errors, dependent on the order of (more...)

One way to find that ORA-942 causing missing grant

| Jan 30, 2013

Hi all,

It has been too long since the last post. It is not that I do not want to, it is just way too busy…

I just came across a small problem where a .NET application written by someone else caused an ugly Stack trace with a ORA-942 (Table or View does not exist) after being moved to the next environment. The error was not there on development, so they asked me what the problem could be. At first I did my compare of grants to the Role I am supposed to use for the application. The problem is (more...)

Installation of Oracle 11 Release 2 on Windows 7 64-bit

| Mar 18, 2011

I never had so much trouble installing an Oracle version on a Windows OS as I had with installation of Oracle 11R2 on Windows 7 (64-bit). The issues I faced were twofold:

  1. First I got messages (during installation of the software) that files could not be found in the target oracle folder
  2. Second, after finding the solution for the first annoyance, I spent two hours finding out why everything installed correctly, I could create a database, but could not start a Listener. I am an Administrator on my laptop. The errors I got at starting a listener were ORA-12560 and (more...)

How to deal with DBMS_RLS

| Feb 7, 2011

How to deal with DBMS_RLS?


These last weeks I am trying to get the VPD option (Virtual Private Database) enabled for my application. This time as a developer with no DBA or SYS privileges. I am used to being a DBA for the databases I work on and am used to being able to get the fullest out of the Oracle database. For one, because I think Oracle provides us with a great deal of built-in features that do things more efficiently than we can do ourselves (more efficient, built-in kernel code) and also especially because it seems useless (more...)

Catching up…presenting and taking part in Challenges

| Jun 14, 2010

I regret not being able to write new things more often, but in fact it only means I am OK: very busy with work, doing private stuff (which is important since life is not all about working), enjoying the three young kids and trying to achieve some good results in track and field. And for that last goal, I can say I did. After a few months of struggling to find a tiny piece of shape comparable to last years shape, just in time I found it. I won the gold medal in the Dutch Championships 400 metres hurdles. OK, be (more...)

One simple web page saved my day

| Jan 28, 2010

As an Oracle specialist you meet it from time to time: something is not working as expected. Lots of times the information is right under your hands on the web. We open Google and search for some error message we get. If I cannot find it there I open Oracle support (for some time already the flashy new site, I am getting used to it after a few weeks of hesitation and missing MetaLink). Probably it should be the other way around: Oracle problems should be explained best on the Oracle support site. And they probably are, but they are (more...)

Oracle Import issues: Resumable and buffer

| Oct 13, 2009

Yesterday and today I noticed two things with Oracle import (in Oracle I did not know:

1. An issue with the buffer parameter in Import
2. An issue with Resumable=Y and FROMUSER/TOUSER where the FROMUSER and TOUSER have different default tablespace and quotas


  • I did a DIRECT export yesterday of a table that contains a LONG column
  • I did an import (which is conventional) of that table with BUFFER=<some value>
  • I got embarrassed because my laptop started beeping around and my screen started screaming weird characters

I went through that embarrassment a few times, because I tried (more...)

DBMS_REDEFINITION, clustering and how an outline helps to make it completely ONLINE

| Sep 23, 2009

At last a new post from my hand after months of silence. Well, silence in writing then: in the mean time we got our third child and I participated in the World Championships Double Decathlon in Delft. Those two things were enough for me to handle next to regular work ;-)

In this post I want to share good experience I had in the use of DBMS_REDEFINITION to speed up the Siebel OLTP application I am responsible for (at least, for the performance part of it). It is about clustering of data and rebuilding tables as ONLINE as can be and (more...)

How the optimizer may use an index for cardinality estimates without actually using it

| May 18, 2009

Recently I was sent a data warehouse SQL query that performed badly. It took more than an hour and timed out. It was the first time that query was run with a particular parameter. Here I will show that to solve this, I created an index to give the optimizer better information, even though it did not actually use it to execute the query.

If I can, I always try to get a feeling for the cardinality estimates the optimizer makes, inspired at first by Wolfgang Breitling. The optimizer is strongly driven by expected cardinality and miscalculations, especially in the early (more...)

The trains are a nightmare, IT’s a Miracle and how little can you know…: Tanel Põder in Utrecht!

| Apr 2, 2009


Networking and evaluations
Networking and evaluations

Today was the first day of the second Miracle Masterclass this year: Tanel Põder has come to The Netherlands, saw a room filled with a lot of people (he called it the best seminar even before he started, just because of the amount of attendants) and made me feel I have an awful lot to explore yet. However, that is in fact a good thing and it made me get through the “trains nightmare” today with a smile: I had trouble in the morning since I left home far too late, had to cycle as fast as I (more...)