Time-delayed replication is a useful feature that allows a slave to lag a fixed amount of time behind a master, thus providing a time window to recover from disasters like deleting a 10 million line table by accident. You just run over to the slave, turn off replication, and recover lost data, as the delayed updates mean it has yet to see your deadly mistake. It's a simple way to protect your administrative honor as well as your job.

Time-delayed replication has been on the MySQL to-do list since at least 2001. It's currently scheduled for release 6.0 and the fix is included in recent OurDelta builds. However, there's a very simple way to get the feature with Tungsten Replicator filters. This works for unadulterated MySQL 5.0 and 5.1 releases.

I wrote about filters in a previous post on the …

I spoke with Brian Aker last week about the issues I found with decrement and increment while working on my book "Developing Web Applications with Apache, MySQL, Memcached, and Perl". He suggested I make sure that I was using the latest libmemcached. I checked, and the version of libmemcached that is included with Memcached::libmemcached is 0.21 - this is the version of Memcached::libmemcached I obtained from using CPAN (perhaps CPAN needs a new bundle...). So, I obtained the most recent version of Memcached::libmemcached from the subversion repository at https://perl-libmemcached.googlecode.com/svn, and it includes the lastest libmemcached, version 0.25. To make a long story short, I re-wrote my test script to test each operation individualy and time that, as well as compare the times to Cache::Memcached. The numbers are great and are reason enough to use …

First of all, let me wish all of you a great year 2009! As an old year ends and a new year begins, it's a good time to do some statistics. One of the statistics that web developers are interested in is, which browsers and operating systems visitors use to access their websites. Let me share some of the interesting figures regarding the mysql.com website with you.


(click to enlarge and see more detail)

The spreadsheet contains data for December 2008 (another sheet for November 2008) in a pivot table style. In the columns you see the browsers and operating system and in the rows the continents and regions, with the shares in the respective cells. Fairly self-explanatory as I hope ;).

Usage shares on the mysql.com site generally favor browsers and …

I've been recently asked for advice on running MySQL on EC2.

• 
  
• Run only a one MySQL server process on the instance.
  
• This bears repeating. Run only the MySQL server on the instance. Not your app server, or your dev environment, or your...
  
• Use the large or xlarge size, not the small size.
  
• Dedicate the additional partitions to be InnoDB tablespaces.
  
• "Pre-heat" the tablespace partition with dd. That is, dd if=/dev/urandom of=/path/to/part bs=8K before using the partition.
  
• This is one of the times where it's worth it to run tablespace on raw devices. Don't bother to put a filesystem down on those partitions.
  
• Tune your database server. Get someone who knows MySQL tuning to do it for you.
  
• Backup and Replicate with rigor. When an instance gets shut down, it …

This keeps happening - the community I need to stay engaged with keeps jumping on new forms of communication, and if you want to stay in tune, you need to jump on too.

This first happened with blogging, and then with Facebook. These I actually don't mind. I like writing and reading blogs, and Google Reader has made it fairly easy for me to quickly digest what's going on.

Facebook is nice because I keep in touch with friends. It's not so much about work but about getting a little more connected, particularly to old friends who I don't see much any more.

But this Twitter thing - I really don't like it. Sorry. I subscribe to someone's Twitter feed because I value their thoughts, but then it's serious drinking from a firehose. Many of these Thought Leaders are just constantly (I mean constantly, like I don't know how they get any work done) …

Due to the efforts of Brian Moon and Michelangelo van Dam, I've been sucked into a meme started by Tony Bibbs. My initial reaction to this unfortunate event was ... (envision Steven Colbert, hands raised...) "Noooooo!!!" But I got over it. Hey, it's the holiday season, I might as well be a good boy and fulfill the modern-day geek's equivalent of a chain letter.

So, without further ado, here is my list of seven things about me you probably could care less about and will skip over to see if you are on my list of tagged people. (Yeah, you know you will.)

• My real name is not Jay
• I have a twin brother, …

2008 was a good year for MySQL Certification. 1,986 folks took exams which is a 14.6% gain over 2007. 736 candidates earned certifications and that is a 14.4% gain. The biggest gains were in Associate (up 300%) and DBA (up 35%) certifications. Oddly the Developer cert was down 40%.

So what happens in 2009?

The DBA and Developer exams are both changing format to performance based tests. Candidates will be tested on a virtual server and provided with a list of tasks that need to be accomplished. The DBA exam is actually in alpha est and about to go to beta. This testing is being done on two sets of virtual environments which provide their own qualities. The Linux environment is probably closer to what most DBA's working environment but the Windows version allows the candidate more control over the system. More news here later in the month.

Computer certifications will take …

When your favourite ex yahoo employee and mysql guru blogs about a "dns problem" and how he solved it using Twitter you can only smile ;) At last some useful use for Twitter .. when it's up at least ..

The future of commercial open source software lies in commercial licensing strategies, but which are the strategies that are more likely to deliver the results vendors are looking for?

Much of the open source blog chatter over the Christmas period was related to open source business models/strategies, largely triggered by a post written by Dave Rosenberg in which he declared that commercial licensing, and specifically open core licensing will be all the rage in 2009:

“Typically we now see an “open core” freely available with “exclusive” or proprietary features only available when you pay. If you are trying to build a commercial business on top of an open source project, this is likely the right answer.”

…

So, my Haystacks teammate Brian DeShong tagged me in his list of seven.  We won
that trivia contest by the way.  It was a real team effort.

So, here goes my seven things:

1. I have six kids.  Okay, let that sink in.  Yes, six.  Logan(12), Macy(11), Molly(9), Parker(7), Collin(3), and Hudson(6 months).  I know what causes it.  Yes, it is hard at times.  But, there are those moments when you are sitting in the yard or in the den and all is right in the world.  The best program I will ever write will not compare to what have done with my children.  They are truly my greatest project.  My wonderful wife blogs about them at Moonmania.
2. I started my career as a Visual Basic programmer.  PHP and VB are very much alike.  …