JL Computer Consultancy

An expert view on the Oracle (tm) database engine


JL Computer Consultancy

Health Warning and Disclaimer

Every book I have ever read about Oracle has been out of date, incomplete, ambiguous, misleading or wrong - some much less so than others but the average time it has taken me to find the first error (or notable omission) has never been more than 5 minutes. This turned out to be true even for the book I wrote, by the way, so be warned that my words of wisdom might not be appropriate to your current situation.

Over the years I have found that, despite days of experimentation and testing, when I start writing about some interesting feature of Oracle the first person to review it says something like "it didn't do that for me" and the reason is eventually down to:

The version of Oracle

The options installed

The choice of operating system

The verson of the operating system

The hardware

The hardware configuration

The choice of filesystem/volume manager

The volume of data

The ratios of data distribution

Some unexpected init.ora parameter

The information on these pages was as accurate as I could make it at the time of writing. However I cannot guarantee that things which worked for me will do the same for you. Nor can I guarantee that the information will remain correct as new versions of Oracle appear.

I have just (April 2004) been browsing through some of the material, and find that a lot of it hasn’t been updated at least five years. Unfortunately I posted a lot of material without date stamps or Oracle version numbers. So make sure you check how relevant something is to your current version. Even if something is still true, it may not be complete, and there may be recent enhancements and developments that you should consider.

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JL Computer Consultancy

What is on this site

Every couple of weeks I hope to put a few more bits and pieces on to this site that may be of use to DBAs, developers, or other Oracle users. These will range from handy little SQL scripts for database monitoring to 'white papers' on how to use various features of the database engine.

You are invited to participate in these web pages by emailing questions, comments, or criticisms. Some of the opinions I tout on these pages are likely to be contentious since I often disagree with the oral traditions (a.k.a. old wives' tales) on how to handle Oracle - if you want to argue a point I'll be delighted to hear from you at jonathan@jlcomp.demon.co.uk.

I don't plan to make these pages very pretty - if you are interested in making Oracle work better you probably don't need pictures to keep you entertained, you're just keen to get the right information. Most of the pages that I put up will be fairly flat texts but from time to time I may upload Word documents or Powerpoint presentations for you to download.

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JL Computer Consultancy

Biographical Information

My name is Jonathan Lewis and I live in the UK a few miles outside London - conveniently located for both Heathrow and Gatwick airports and an international range of clients.

I have been using database software for more than 25 years, of which the last 23 have been spent using the Oracle RDBMS. For the last twenty years I have worked as an independent design and trouble-shooting consultant. Much of the work I do is very short-term, often just a couple of days to investigate and advise on troublesome systems – sometimes with repeat visits to keep complex projects moving in the right direction.

The systems I have worked on range from a single NT up to 128-node Pyramid RM1000, the databases have ranged in size from a tiny (but violent) 50 Mb to several Terabyes with transaction rates from just 60 per day up to 4M per hour, and the locations I have visited have varied from 155W (Palo Alto) to 175E (New Zealand).

I specialise in knowing how the database engine works. If you need to know which features of Oracle may be useful for your specific application I will be able to tell you because I spend a lot of my time investigating how well new features work, whether they work together, and how easy it is to break them. If you need to make your system run faster I can tell you what can be done and what is most likely to be a cost-effective approach.

I have given several presentations each year to the UK Oracle User Group, both at the annual conference and at meetings of the UNIX and DBMS SIGs. I’m also a regular presenter at the Danish Database Forum (Miracle Open World) and usually present at a couple of events each year in America (my first trip to the US was the IOUG-A conference in 2003 where both my presentations were voted into the top 10 – and I’ve been welcomed at various other American events since then).

I write fairly regularly for the UK user group magazine Oracle Scene and occasionally for other publications. Most significantly, though, I am the author of Practical Oracle 8i - Building Efficient Databases, published by Addison-Wesley, and Cost Based Oracle – Fundamentals, published by Apress – with contributions to three other books to my name.

Last, but not least, I am the designer and presenter of a number of one-day and two-day tutorials designed to help you get the most out of the database engine. I have presented these courses around the world, both as public events and as private events for large corporations (including Oracle University, in their “Celebrity Seminar” series) – clocking up visits to 49 different countries so far.

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Contact Information

Electronic mail address jonathan@jlcomp.demon.co.uk

Web address http://www.jlcomp.demon.co.uk

Office phone +44 (0)7973 188785

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Last revised: 10 October 2010.