Of course you’ve heard about the fabulous pybots project, where community members have a distributed network of computers continuously testing every change in the development version of python against the development version of many different python applications. This ensures that any compatibility problems are caught early, well before the next version of python is released.

I’ve just about finished getting storm, the newly open sourced python object-relational mapper that we are using with Launchpad and Landscape, added into the pybots test suite. Just need to finish reading through an 18MB test log to figure out what I did wrong in the test script for the psycopg2 installation, and we should be all set, with storm being tested against MySQL, Postgresql, and SQLite. Rumour has it that Firebird support is coming soon (perhaps even …

It will be Sunday, September 23rd at Taste from 1PM to 10PM. I’ll be there, along with the Ubuntu Florida team. Hopefully develpers from MySQL and Pentaho will go also! Possible topics I am considering speaking on include Bazaar, Launchpad, Ubuntu, MySQL, hiring and managing an international development team, how to evolve your database schema without going insane, and using bluetooth PAN networking with laptops. If you are going, what would be most interesting to you?

We’ll be doing a linux install-fest, so bring along your laptops and ubuntu CDs. I’ll also be able to answer questions on how to use Bazaar with a variety of different development workflows. We also need sponsors, so check out the website to learn more.

Sadly, it’s not my bug, it’s a bug in the MySQL Documentation.

http://bugs.mysql.com/bug.php?id=29915

I’m actually quite surprised nobody has run into this before, and in fact many sources quote this stating that %I and %h are the same thing.

I can’t be the only person in the world that’s ever needed hours with stripped leading zeros before. The irony is that before the submitted bug I was 5 points away from being a Basic Quality Contributor, and it would be very funny to me if this is the bug that pushed me over to qualify for a free Basic license….particularly since my company JUST bought a few licenses a month ago.

So I need to create a portal site, where we will require multiple frontends. As most portal's we need to store some state information inside a session. We also need to show how many users are online, but more importantly be able to filter searches in the member database by who is online (we do not need to filter by how long the last site interaction as been, but you never know with changing requirements).

Now in order to filter by users in the member search, we need to have some information about active sessions by user id inside MySQL database. But if we were to put the entire session data inside the database we would have to hit the master on every request to update the session timeout. More importantly we would have to deal with replication lag.

The alternative approach to working around replication lag is using memcache. But with memcache we would not have access to who is currently online in an easy queryable way when we are …

Optaros, the company I am working for, released an open source catalog which lists close to 300 so called "enterprise ready" OSS applications. I guess most of you reading my blog are not exactly in the target group as to me it mostly seems to be directed about people that lack deep networking into the various OSS communities. That being said I still think that it might be worth a look, even if its just to blog about how we totally got the rating on a specific piece of software totally wrong.

In this updated and web enabled version end users can vote on projects, which is already a first step in the direction of allowing user contributions. I hope we will figure out ways on how to expand this. Again the target group are decision makers that are not so in tune with OSS communities, so we are ok with providing a little less information (if they want all the information they can always use …

Georg, Andrey and Ulf have been hard at work designing, implementing and testing a replacement for libmysql only for us PHP users. The idea is that mysqlnd can leverage all the internal PHP infrastructure for communication and memory management. It can also be much more PHP aware, removing old cruft we do not need while adding extra goodies just for us!

This means the PHP memory limit will finally be honored, PHP user streams will be able to hook into the communication with MySQL. A client side query cache promises speed improvements and the fact that data does not need to be moved from libmysql to PHP should also stream line things. They are also looking to improve support for persistent connections.

While originally developed for PHP6, mysqlnd now also runs on PHP5 and talks to ext/mysqli and ext/mysql with PDO support planned. More over the …

Using the LAMP Virtual Appliance, it is possible to create a full Django development environment in less than 15 minutes.

This article assumes that the reader is already familiar with VMware virtualization products and has one of the following products installed and functional on their host operating system: VMware Player (free download), VMware Server (free download), or VMware Workstation.

Download the LAMP VA (build 131 or newer) and configure for your environment.

Assuming a …

One interesting solution to scalability and HA is to implement a circular master-master replication setup directly on the frontend servers. Obviously there is a reasonable limit as to how many servers you can have in such a ring, since the lag with which changes propagate will increase linearly as you add more servers to the ring. However according to an article by Giuseppe a 10 server ring is reasonable. Especially if you make your sessions sticky on a per frontend server basis, you actually have an elegant solution against the old issue of replication lag, where a user does not see changes he has made in subsequent requests, since his changes were written to a remote master server which have not propagated to the slave he is reading in the subsequent request. Latency should also improve as you do not have to open up a remote connection in the …

I just wanted to point everybody at a recent blog post by Konstantin. In the post he discusses a solution for dealing with cache invalidation issues of very large caches under heavy load. He points out that cache invalidation can severely bog down the system. The general solution he proposes is to simply deactivate the query cache entirely during invalidation. I think this is an important caveat to be aware of and actually he is asking for feedback if this "solution" is acceptable. I think its awesome that MySQL engineers are giving us the opportunity to provide feedback on such changes. Maybe there should be a dedicated "pipeline" where such requests could be found?

So the other day I stumbled over the slides of the InnoDB talk at this years MySQL users conf and I noticed "gap locking" somewhere in the middle. I have never heard of "gap locking" so I was quite intrigued by what that might be. From what I understand its InnoDB's solution to implementing REPEATABLE READ (though until MySQL 5.1 it seems this feature is also enabled for READ COMMITTED). I guess its a fairly unique approach and from my current understanding to be feasible it expects short running transactions, which luckily are quite common in web applications that most of us care about.

The problem InnoDB is trying to solve here are situations where overlapping transactions cause phantoms. Now the first surprise was when I read that gap locking is implemented by locking the relevant ranges on the index or more particular …