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Indexes, Low Index Selectivity and Index Performance
Partial Outer Join

I was wracking my brain for a bit, and could not figure out how to do a partial outer join where I was limiting rows from one table. So, I went to post to the MySQL user list — in writing my post, I found the answer. This often happens. It’s not that I don’t have questions to ask the MySQL user list (or forums), it’s just that most of the time, while I’m writing up the question, I find my answer.

First, I simplified my question. Many people do this, but they leave out important information. The trick is to come up with a simplification that you test to make sure it breaks in the same way the more complex, “real” query breaks.

The problem is basically this:
I want an outer join of a static table with a data table, such that I get a report of how many rows in the data table match the static table — including “0″ if there are none, but for a subset of the data in the data table. Consider a …

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What's on O'Reilly's Open Source Executive Radar?

I've been fortunate to be able to help Tim put together the Open Source Executive Briefing for the O'Reilly Open Source Convention this year. Fortunate because my views of open source tend not to stray far from "What will make my company more money today?" Tim, of course, tends to think in terms of years and decades, not days and weeks. So working with him has helped me see a bit farther out into the darkness to see where open source is going.

The picture is very, very bright.

However, most people will continue plodding along in their "open source is about commodification" mode, missing out on the bigger picture(s), unless they attend. There are very few events that I think can fundamentally change the way you look at, invest in, and monetize open source technology. This …

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OmniTI Seeks Junior Security Analyst

Are you a good PHP developer searching for a cool place to work?

OmniTI (where I work) employs several industry leaders, including Theo Schlossnagle, George Schlossnagle, Laura Thomson, and Wez Furlong. We do lots of interesting, challenging work for some of the largest and most recognizable names on the Internet. Not only do we predominantly use open source technologies, our staff are major contributors to many notable open source projects. In other words, I think this is a really cool place to work. :-)

We're expanding our web application security practice and are looking to hire some experienced PHP developers who are interested in learning all about web …

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All Good Things ? Leaving MySQL

After the two best years of my career to date, I will be leaving MySQL AB this coming Friday, July 14. Over that last two years as a member of the MySQL AB documentation team I have had the pleasure of working with some of the finest people I have ever met. MySQL is full of talented developers, trainers, writers, consultants, support people, etc. As a result, I have learned so much and will take so much away with me.

Why leave? The simple answer is that I have been made an offer I can’t refuse by a company called OmniTI. It offers new challenges, new work, and a new group of talented coworkers. I’ll be covering my new experiences in future posts.

Going forward, I still plan to be a vocal supporter of MySQL, continuing my efforts as a blogger and speaker. I will continue to submit MySQL-oriented sessions at conferences, and also plan to produce more articles and videos. MySQL has always had a great community and I’m looking …

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How much memory Innodb locks really take ?

After playing yesterday a bit with INSERT ... SELECT I decided to check is Innodb locks are relly as efficient in terms of low resource usage as they are advertised.

Lets start with a bit of background - in Innodb row level locks are implemented by having special lock table, located in the buffer pool where small record allocated for each hash and for each row locked on that page bit can be set. This in theory can give overhead as low as few bits per row, so lets see how it looks in practice:

I used the same sample table as yesterday:

PLAIN TEXT SQL:

  1. CREATE TABLE `sample` (
  2.   `i` int(10) UNSIGNED NOT NULL AUTO_INCREMENT,
  3.   `j` varchar(255) DEFAULT NULL,
  4.   PRIMARY KEY  (`i`),
  5.   KEY `j` (`j`)
  6. ) ENGINE=InnoDB DEFAULT CHARSET=utf8
  7.  
  8. mysql> SHOW TABLE STATUS LIKE "sample" …
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Day One of New EU Patent War

- PRESS RELEASE -

DAY ONE OF NEW EU PATENT WAR:
EU COMMISSION PUSHES FOR LITIGATION AGREEMENT

EU internal market commissioner McCreevy said at yesterday’s hearing
on the future of European patent policy in Brussels that he wants to
“move forward” with the European Patent Litigation Agreement (EPLA) -

Anti-software patent campaigners vehemently oppose the EPLA,
claiming it is “from a software patents point of view […] far worse”
than the directive they defeated in the European Parliament last year

Brussels (July 13, 2006) - At yesterday’s European Commission hearing in Brussels on the future of European patent policy (http://ec.europa.eu/internal_market/indprop/patent/hearing_en.htm), the EU’s internal market commissioner Charlie …

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Political reasons for FOSS

Pia Waugh recently wrote an excellent article on economic and social reasons for using FOSS. It's for Australia, but of course it applies almost everywhere. You may find it useful!

As Pia says, "getting the right information to the right people in the right order to get a right outcome." or as I generally note, "don't try geek arguments on non-geeks." ;-)

Arjen is going to catch a train (in the US)

Yes, apparently it's quite unusual to use a train in the US. But consider this... for a trip of upto a few hours, it might even be faster if you take into account having to be at the airport early, etc. Much less hassle, more seat space, and with a business class seat you even get an AC socket so you can plug in your laptop! And it's definitely cheaper.

I'm travelling to Portland next week, for OSCON. My trip from home in Brisbane, Australia will take me via Auckland (New Zealand), and then into San Francisco. When going to the US I always start a few days early, so when an event starts I'll be past my jetlag... I'll first stay in Cupertino (Silicon Valley) for a day, visiting our US offices there. Then fly up to Portland. I already had that booked. So why the train?

Well, Brian just invited me to visit Seattle for the few days before OSCON. It appears that various MySQL people will be there, actually, and that's a great …

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At least four unsuccessful bugfixes in MySQL 5.0.23

MySQL 5.0.23 will not be officially released due to the fix for bug #10952 (an ALTER TABLE to MERGE or BLACKHOLE should have been forbidden to prevent the loss of data in the table). The fix introduced some unwanted side effects and needs to be reverted in the upcoming release 5.0.24. But this was not the only bugfix with negative side effects in 5.0.23: I tried the build today and just discovered three other bugfixes introducing new bugs while actually trying to fix old ones.

Just a few days ago Baron Schwartz wrote an article on how to replace large IN clauses with a UNION SELECT

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