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October 2009

SystemTap is production supported in Redhat EL5.4

If you don’t know what SystemTap is – it’s the Linux world’s attempt to build Solaris DTrace style safe dynamic instrumentation into Linux kernel.
I’m not going into religious discussions which one is better here, I have used both SystemTap and DTrace successfully for diagnosing low level issues inside OS kernel, so both are good enough for me :)
The problem with SystemTap though has been that it’s not production quality, it’s rather been a technology preview.

SystemTap is production supported in Redhat EL5.4

If you don’t know what SystemTap is – it’s the Linux world’s attempt to build Solaris DTrace style safe dynamic instrumentation into Linux kernel.
I’m not going into religious discussions which one is better here, I have used both SystemTap and DTrace successfully for diagnosing low level issues inside OS kernel, so both are good enough for me :)
The problem with SystemTap though has been that it’s not production quality, it’s rather been a technology preview.

SystemTap is production supported in Redhat EL5.4

If you don’t know what SystemTap is – it’s the Linux world’s attempt to build Solaris DTrace style safe dynamic instrumentation into Linux kernel.
I’m not going into religious discussions which one is better here, I have used both SystemTap and DTrace successfully for diagnosing low level issues inside OS kernel, so both are good enough for me :)
The problem with SystemTap though has been that it’s not production quality, it’s rather been a technology preview.

SystemTap is production supported in Redhat EL5.4

If you don’t know what SystemTap is – it’s the Linux world’s attempt to build Solaris DTrace style safe dynamic instrumentation into Linux kernel.
I’m not going into religious discussions which one is better here, I have used both SystemTap and DTrace successfully for diagnosing low level issues inside OS kernel, so both are good enough for me :)
The problem with SystemTap though has been that it’s not production quality, it’s rather been a technology preview.

CBO: NewDensity for Frequency Histograms,11g-10.2.0.4 (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 10.2.0.4 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... Snopes.com pointed out this morning that the use of a 'bad default value' dates back to at least 1979...

See http://tkyte.blogspot.com/2009/10/back-from-oracle-openworld.html 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.

But....

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.

http://tkyte.blogspot.com/2006/01/something-about-nothing.html
http://tkyte.blogspot.com/2006/01/mull-about-null.html

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.