Northern Server Technology Day – presenting again.

I’m presenting again on 27th April at the Northern Server Technology Day – a cut down version of my last presentation this time – just a couple of the topics which I’ll hopefully be able to do a little more detail on and a little less rushed.

I’m second on after Doug Burns and his latest paper – How many slaves ?.

Should be a good event – see you all there!

On the blog front, thanks to Justin Kestelyn earlier today I’m now on – lets see what that does to traffic.

Scary…but not so bad! (…presenting that is)

Well, my first presentation at the BIRT SIG seemed to go down pretty well then…everyone seemed to have positive comments which was really nice…made the need to change my underwear that bit more bearable!

My attempt at humour even had the audience laughing which was great.

I definitely need to learn more about timing though! Last night’s practice run throughs were taking 55 minutes…the slot was 45 mins! I told Mark when I arrived this morning that I might struggle for time…but in fairness a number of the earlier presenters had also struggled for time as well…so he said just go for it. By the time 45 minutes had passed I was just finishing tip 3 of 5 and Mark was holding up his watch to me! I managed to rattle off the salient points of the last two slides reasonably quickly and took a couple of questions and everything ended with a confidence inspiring round of applause…which was really nice!

It was actually a really interesting day with lots to take from the many presentations that were given…if you’re not a member you really should be!

Kevin Lancaster from Oracle gave a couple of interesting presentations on Analytic Workspaces…I really need to investigate how these might help my current client with their warehouse. Donna Kelly had some interesting views on the highs and lows of Oracle Warehouse Builder from her past few years using the tool whilst Mark Rittman also gave an interesting presentation on XML Publisher…the new reporting tool. David Walker gave a very interesting presentation on Process Neutral data modeling which reassuringly had some similarities to the design I’ve just implemented…although it did leave a number of things to think about.

I must say a big thanks to everyone who reviewed my presentation:

Lisa, Nick, Niall, Doug, Pete, John, Anthony and Andrew.

…your time in doing so was much appreciated and your comments were all valuable.

I’d like to thank Doug Burns especially as he gave me a great deal of confidence during my preparation for the event – you were right as well Doug, the feeling on finishing the presentation and hearing the applause was a buzz!

I was collared by a couple of people after the event and asked to present the same paper again at future events…I’m seriously considering it.

If you’re a member who hasn’t yet presented I would urge you to do so…it’s very educational and rewarding.

Hopefully I’ll have more time to blog now…watch this space.

Improving the Oracle community

My presentation is almost finished for the UKOUG BIRT SIG – just going over the comments I’ve had back from a number of reviewers – most of which seemed to be quite positive about the content whilst also being unanimous about the fact I’d got too much content for the available time – I think I knew that but, having not done this before, I just wanted to be in a position where I could chop stuff down to size rather than be worrying about “padding” things up to time.

Doug Burns suggested my confidence might be buoyed by this addendum on the Snark piece over at Jonathans website…can’t say I disagree with Doug and it just goes to prove a number of things:

  1. Put stuff out there and over time it will either be agreed with and supported by other evidence or it will be disproved/clarified – but at least the quality of the available knowledge will only get better.
  2. Of course there are some individuals out there who are considered “Oracle Gods” but they aren’t omniscient and they like nothing better (I’d like to think) than being challenged about what they’ve said and being proven wrong/misleading on something they’ve said so that it can be corrected/improved/clarified – at least they had the guts and generosity to say it and publish it in the first place as a forum for us all to use or build on.
  3. Generally those “Oracle Gods” are actually very approachable, educational and pleasant people who want this community to get more proficient and effective at what we do.

Anyway, gotta go – Pete Scott came up a with a few technical queries on my presentation content during his review…I’m gonna have to go read up on some stuff as, typical of Pete, his questions are thought provoking to say the least!

Presentation Agenda: Five Tuning Tips For Your Data Warehouse, UKOUG BIRT SIG, 31st January, 2006

So, the agenda for my presentation at the UKOUG BIRT SIG on January 31st is going to be something like this:

Abstract: Just like OLTP systems, Data Warehouse performance can be affected by a myriad of factors. This presentation will cover Five key areas which can have a significant impact on warehouse performance:

  • Make the most of your memory
  • Partition for performance & manageability
  • Squeeze your data with segment compression
  • Beware Of Temporal Data Affecting The Optimizer
  • Find Out Where Your Query Is At

Each of these are major topics in their own right so I’m not going to cover an enormous amount of ground with each, but I will try to cover some key points and include a demonstration or two along the way.

I’ll be putting the slides together over the next few weeks so I guess I’ll be posting less (already have been…but that’s due to this man flu still hanging around).

I have come across a couple of interesting things along the way already mind:

Firstly, I was trying to tune a Materialized View the other day when I encountered something which made me laugh. I extracted the DDL from Toad and tried to do an explain plan on it…only to discover that it rewrote the query using the Materialized View – well, of course, it would, wouldn’t it! In order to tune it you need to add the NOREWRITE hint.

My colleague Anthony Evans encountered a similar problem afterwards when trying to tune a query which referred to a view which was undergoing a Materialized View Rewrite when he didn’t want it to. The solution he found in this case was to use the NO_QUERY_TRANSFORMATION hint to instruct the optimizer to skip all query transformations.

The next thing I discovered was when building a test script to test compression out. I was doing a series of INSERT /*+ APPEND */ operations with COMMITs after them which was working fine. Then I added SET AUTOTRACE ON at the start of the script so I could start to see the execution plans and statistics but unfortunately this resulted in this error:

ORA-12838: cannot read/modify an object after modifying it in parallel

The AUTOTRACE is doing some more DML after the INSERT /*+ APPEND */ but before the COMMIT…which is not allowed when using the APPEND and so it breaks.

I resorted to using SET AUTOTRACE ON STATISTICS instead since I wasn’t too interested in the execution plan anyway. I guess I could have used tracing and tkprof if I’d wanted to see the execution plans as well.

My First UKOUG SIG Presentation!

In a moment of “man flu” induced weakness I’ve bowed to a request from Mark Rittman to present something on data warehouse tuning at the UKOUG BIRT SIG on 31st January, 2006…trust him to catch me when my guard is down huh!

Not quite sure what to present really so gotta think of an outline over the next week or so…as if I don’t have enough to do at work already!

When I’ve got an abstract and outline ready I’ll send it to the SIG guys and then post it here for interest.

I hate presenting but I was motivated by people like Mark and Tom and many others who regularly give everyone the benefit of their experience by participating in the many opportunities to share hard earned knowledge.

See you there – be gentle!