Megabytes of text had been written already on InnoDB locking and deadlocks. Still, even very simple cases of deadlocks while working with a table having only one row sometimes make people wonder what happened and why.

Today I want to check if this topic is explained well in the manual and existing blog posts and understood properly. So, it's an exercise for my dear readers and those who like to report bugs as much as I do.

Let's consider a very simple example. In session #1 with default transaction isolation level execute the following:
CREATE TABLE `tt` (
  `id` int(11) NOT NULL,
  `c1` int(11) DEFAULT NULL,
  PRIMARY KEY (`id`),
  UNIQUE KEY `c1` (`c1`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
insert into tt values(1,1); -- insert a row there
select * from tt; -- check that we have row (1,1)
begin work;
select * from tt …

The call for participation at Percona Live MySQL Conference and Expo 2014 is now closed. There have been more than 320 submissions, and this will keep the review committee busy for a while.

One important point for everyone who has submitted: if you have submitted a proposal but haven’t included a bio in your account, do it now. If you don’t, your chances of being taken seriously are greatly reduced. To add a bio, go to your account page and fill in the Biography field. Including a picture is not mandatory, but it will be definitely appreciated.

Although the CfP is closed for tutorials and regular sessions, your chances of becoming a celebrity are not over yet. The CfP is still …

I've just noted the date... 8 years ago I had my first official working day as a support engineer in bugs verification team of MySQL Support at MySQL AB. Why not to celebrate this anniversary with a blog post about bugs?

So, here they are, 12 oldest bugs in MySQL software that are still just "Verified" (it should mean they are accepted, but not yet fixed):

1. Bug #2 - MySQL Connector/J doesn't make toast. I knew that Connector/J must be the most broken MySQL software (as I hate Hibernate). Now you can see how much it is broken, and nobody cares to fix it since 2002! This is a real shame...
2. Bug #199 - Innodb autoincrement counter is lost on restart. This great report from Peter Zaitsev is still "Verified", since 2003. It became a documented "feature" in …

After a long pause in the speaking game, I am back.

It's since April that I haven't been on stage, and it is now time to resume my public duties.

• I will speak at MySQL Connect in San Francisco, just at the start of Oracle Open World, with a talk on MySQL High Availability: Power and Usability. It is about the cool technology that is keeping me busy here at Continuent, which can make life really easy for DBAs. This talk will be a demo fest. If you are attending MySQL Connect, you should see it!
• A happy return for me. On October 27th I will talk about open source databases and the pleasures of command line operations at …

Introduction

Object-relational mapping (ORM) frameworks have been around for several years now and for some people, ORM is already outdated by now. As we have seen with other technologies and concepts before, PHP is not exactly what we call an early adopter among the programming languages. Thus it took some time for ORM to grow up in the PHP context.

There have been some frameworks before Doctrine 2 that implement ORM (remember e.g. Propel) specific tasks but most of them lack the required maturity to be used in large projects. With Doctrine 2, PHP takes a huge step into the right direction Doctrine 2 is fast, extensible and easy to use.

This article will take you on a tour through the main concepts of Doctrine 2 in the first part and then explain how to use it in a real world application in the second part. Since at the time of writing …

1. Phantom of the Flopera (YouTube) -- Bach's Tocata and Fugue in D Minor (BWV 565) as performed by floppy drives. Creative intimacy with one's tools is a sign of mastery. (via Andy Baio)
2. Save Entire BBC Archive (Ben Goldacre) -- I pointed earlier to the questionable BBC closure of scores of websites in the name of cost-cutting. It's a torrent of an archive of spidered BBC websites. (via Andy Baio)
3. Android Hidden NFC Capabilities Unlocked -- Gibraltar Software Factory, based in Argentina, …

The Danish "julehjerte" is apparently a Danish/Northern Europe Christmas tradition (at least according to Wikipedia). But hopefully people outside this region will also be able to enjoy this variant:

I have been doing "julehjerter" ever since I was a small kid, and every Christmas try to do something different with it. As seen above, this year I decided to combine the tradition with the MariaDB logo, and I am frankly quite pleased with the result :-)

ScaleDB is proud to announce the introduction of a database that takes data storage to a new level, and a new altitude. ScaleDB’s patent pending “molecular-flipping technology” enables low energy molecular flipping that changes selected water molecules from H20 to HOH, representing positive and negative states that mimic the storage mechanism used on hard drive disks.

“Because we act at the molecular level, we achieve massive storage density with minimal energy consumption, which is critical in today’s data centers, where energy consumption is the primary cost,” said Mike Hogan, ScaleDB CEO. “A single thimble of water vapor provides the same storage capacity as a high-end SAN.”

The technology does have one small challenge: persistence. Clouds are not known for their persistence. ScaleDB relies on the Cumulus formation, since it is far beefier than some of those wimpy cirrus clouds. However, when deployed …

This is the 182nd edition of Log Buffer, the weekly review of database blogs. Make sure to read the whole edition so you do not miss where to submit your SQL limerick!

This week started out with me posting about International Women’s Day, and has me personally attending Confoo (Montreal) which is an excellent conference I hope to return to next year. I learned a lot from confoo, especially the blending nosql and sql session I attended.

This week was also the Hotsos Symposium. …

Others have done it, so why shouldn’t I do it, too? Well, usually that’s not my line of thought, but when today I read David Linsin's blog post about his stats I thought I might follow along.

Overall stats

The overall visits to my blog – and countless others with no doubt – display the workday/weekend jagged line one would expect. The summer months seem to be a little lower on average, but that’s ok, people deserve their vacations. Blue line is 2009, green line is 2008 for comparison.