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February 2013


If you’re a regular follower or my blog you may recall Kyle Hailey and the joint webinar we did nearly two years ago on “Visual SQL Tuning” covering an approach I’ve written about in the past and a product that he developed at Embarcadero to automate the work that I’d been doing by hand and eye.

RHCE Certification Articles (continued)…

I mentioned in my previous post on this subject that I had 5 more objectives yet to cover. The articles for those objectives have now been added to the website.

Understanding Oracle Optimizer Statistics Webinar Follow-up

Thanks to everyone for attending today's webinar on Understanding Oracle Optimizer Statistics sponsored by Embarcadero Technologies. I appreciate everyone who took time to join me today and hope you found it informative.

The webinar recording will be posted within in the next couple of days, but you can download the presentation file now.

Understanding Oracle Optimizer Statistics - presentation

I'll provide the link to the recording as soon as it's available and will update this post with Q&A from the webinar sessions shortly.

Thanks and again and see you in March when I'll be presenting "Back to the Future: Oracle SQL Performance Firefighting using AWR."

Lob CACHE vs NOCACHE – impact on flashback logging


I was doing some work for a client, and LOB processing seemed incredibly slow.  After some poking around, it appears that LOB processing is quite sensitive when it comes to flashback mode in the database. Test bench is a simple table with three clobs. 4kb will be insert into each clob in 5000 individual inserts. The "wait" option is applied to the commit to ensure that the standard PLSQL commit optimizations do not come into play.

Database is running in flashback mode.

Off to Norway !


In April I’m off to that famous conference that so many speak about with affection…

The conference on a cruise ship !

There’s a great line up of speakers – if you get a chance, please come along.

RMOUG, IOUG Collaborate, KSCOPE, and E4 2013

I’ve been really busy lately doing a lot of stuff, and most of the time if I’m doing some intensive research on a topic
I would just put them all in my braindump (wiki) so if you’ve been following this blog might as well subscribe on my wiki RSS because there are just a bunch of bits of research going-on (see this mindmap) and what usually happens is I put them all together to make an awesome presentation/white paper.

Why does my full table scan take 10x longer today ?!

Every so often a DSS query that usually takes 10 minutes ends up taking over an hour.  (or one that takes an hour never seems to finish)

Why would this happen?

When investigating the DSS query, perhaps with wait event tracing,  one finds that the query which is doing full table scans and should be doing large multi-block reads and waiting for “db file scattered read” is instead waiting for single block reads, ie “db file sequential read”.  What the heck is going on?

Sequential reads during a  full table scan scattered read query is a classic sign of reading rollback and reading rollback can make that minute(s) full table scan take hours.

Oaktable World video: Database Virtualization and Instant Provisioning

Slides available at: Database Virtualization and Instant Cloning

Thanks to Marcin Przepiorowski  for editing videos and Tim Gorman for funding the videos. For a full list of Oaktable World 2013 videos see

A completely new and totally different database virtualization presentation will be given at

Enkitec Extreme Exadata Expo (E4) 2013 – Call for Papers

Enkitec E4, the only exclusively Exadata-focused conference in the world, is going to be back this this year too! :-)

It will take place on 5-6 August 2013 in Four Seasons Hotel & Resorts in Irving, TX. It will be very hot in Texas then, but the hotel has a really cool pool there (which I intend to be able to use this year – last year I had to spend all my free time working in the hotelroom unfortunately). And they have beer inside too :)

There will be very good speakers showing up this year too (including the keynote speaker who’s awesome, but I can’t say the name yet) and I’ll hang out there too. I think I’ll deliver a live demo / internals hacking session this year (that way I don’t have to spend my night before the conference preparing slides and can focus more on the cool stuff).

Bullet to the Head…

After boring myself to tears watching The Hobbit, I lost my cinema mojo for a while. I’ve struggled to motivate myself to get involved. Tonight I decided to give Bullet to the Head a shot ( ouch :) ) at revitalizing my cinema spirit and you know something? It did it!

Stallone is a low grade hitman. His partner gets killed, so he accidentally teams up with a cop and goes on an ultra-violent killing spree of revenge.