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October 2009

CBO: NewDensity for Frequency Histograms,11g- (densities part IV)

As we have seen in the previous posts of this series, in 11g a new figure named "NewDensity" has been introduced as a replacement for the "density" column statistic for columns whose histogram has been collected; this change has been backported in also.
In the previous post we discussed how NewDensity influences the CBO [...]

Use NULL for unknown data...

Hah, it goes back much further than I thought... pointed out this morning that the use of a 'bad default value' dates back to at least 1979...

See for the original reference.

Back from Oracle OpenWorld

I am back and have been taking a set of new questions on asktom. Last week was a busy one out in California and I'm finally getting caught up on emails and questions (100% on the former, still working on the latter)

Anyway, I saw an article and it made me laugh - and sort of cry at the same time. It has to do with the use of default values. A lot of developers/DBAs have a very certain fear (that is the best word I can think of to describe their attitude) of NULL - the 'unknown' value. So, instead of using NULL for an effective_end_date field (for records that we don't know the end date for, they don't have one) or using NULL for values they do not know the value of - they use some 'fake' value. This fake value is assumed to be a value that could never possibly be used.


Things change over time.

I'm sure when the developers implemented this system - using XXXXXXX for a license plate value that was unknown seemed 'reasonable'. I mean - who would ever ask for a vanity plate with seven X's on them?

Talk to the guy with almost $20k in fines that aren't his to see if he might know someone that might want a vanity plate with XXXXXXX on it :)

Do not fear NULL.

Understand it, but don't fear it.

Things that make you go "hmmmmm"

I was reading a blog post entitled How Good is Good?. It was written 8 years ago by a graphic designer by the name of Stefan Sagmeister. The post was speaking about creating designs that were meaningful and make an impact on the world (or the part of the world each design is directed toward). While the post was interesting, it was one of the comments that caught my eye. Most of the commenters were inspired by the post but one commenter, in reference to the idea of making a match between good causes and good design a priority vs the more mundane every day marketing stuff, said:

Simple, don't go into graphic design, Choose something else. Cause if you don't do "that" work, other designers will. Do people really think that everybody enjoys their job?

OpenWorld 2009 Recap

Having now had several days to recover from, and reflect on, my trip to beautiful San Francisco for Oracle OpenWorld 2009, I wanted to follow up with a blog post describing my experience. First, before anything else, I went to In-N-Out Burger where I had my usual Double-Double with fries animal style; oh, how I missed thee. Next, with the […]

Oracle Closed World - now closed

It's Friday morning and I'm on my way away from San Francisco after a splendid week of OOW, good guys, a few beers, and a lot of tech talk.

We ran OCW four times from Monday to Thursday, and it was really good presenters we had talked into showing up:

Monday: Jeff Needham on processors and how Oracle runs on them. Opteron good. Nehalem good. A reporter named Kate was present in order to write about OCW. Code: 41.

Tuesday: Jonathan Lewis showing why the crowd were not experts. Ouch. Code 43.

Wednesday: Jeremiah Wilton about the Cloud, and especially the Amazon Cloud. He seems to know a good deal about Amazon. Code 24.

Thursday: Uri Shaft on counting eg. NDV in the optimizer, and some compression theory - and then Dan Norris & Greg Rahn about the Database Machine. Code 42.

OOW09 and my favorite 11gR2 feature

I decided to wait until the end of Oracle Open World 2009 before I posted anything. So many people have been tweeting and blogging and shooting video of this year's event, I figured I'd put in my two cents worth at the end.'s been a l-o-n-g week. I don't know if it's my increasing age or what, but being in a herd of this size for an entire week has left me feeling somewhat bruised (both physically and mentally). I started at 9am on Sunday morning by attending Tom Kyte's keynote for Oracle Develop and have made it through Thursday - which seems like a minor miracle somehow. But I have survived!

So much goes on here, it's hard to keep moving through it given the mass of people and multiple session locations (not to mention the after hours opportunities for fun and frolic). Add a bit of rain (some kind of monsoon as it seemed to me) and, at times, it was like being in an undersized kennel filled with wet dogs. :)

OOW09 Session#4 DBA 11g New Features

For all those who came to my last of my four sessions - 11g New Features for DBAs - I appreciate your taking the time. It was a pleasant surprise to see about 500 people showing up at a lunch time slot on the last day of the conference.

Here is the presentation link. I hope you enjoyed the session and found it useful.

External table enhancements in 11g

Encryption, compression and preprocessing for external tables in Oracle 11g. September 2009

OOW09 Session# 3

I just finished the third of my four presentations - SQL Plan Management. Considering it was at 9 AM on the last day of the conference, right after the big Aerosmith concert, I was expecting a lot less crowd. But, to my pleasant surprise about 150 brave souls turned up. Thank you all. I hope you found it useful.

Here is the presentation material. While you are there, feel free to browse around. And, of course, I will highly appreciate if you could send me your comments, either here or via email - whatever you are comfortable with.