Here’s my presentation on Memcached and MySQL:

This Saturday, May 10th, is MinneBar, Minnesota’s BarCamp. MinneBar is described as an “(un)Conference” which means it’s a free, ad-hoc gathering of technology folks where everyone is encouraged to contribute.

There are a lot of great sessions this year. I’ll be giving a presentation titled “Memcached & MySQL Sitting in a Tree.” The talk is about the new Memcached Functions for MySQL. I’ll talk a bit about the what, why, and how about this set of awesome UDFs.

I’m not sure what time I present and I think I have 50 minutes, but I don’t know for sure. I’m trying something new this time around; I’ll be publishing my presentation on SlideShare.

We are still 3 days away and there are currently 356 people signed up which is right around how many people were signed up last year. If you are in the Minneapolis/St. Paul area, you should come to participate and learn!

To register, visit their website, click the “login” link in the top right, use the password “c4mp” to login, then edit the main page, and add yourself to the bottom. Registration starts at 8:00am, so remember to set an alarm.

Hope to see you there!

Keynotes

The keynote was kick started by Marten Mickos.  If you’ve never met Marten, he is, on a personal note, one of the greatest CEOs I’ve ever met.  The keynotes were especially interesting for me because it was the first time I’ve had the opportunity to listen to Jonathan Schwartz, the CEO of Sun Microsystems.  Jonathan seems like a great guy who gives the impression he "gets it".

The last keynote was by Werner Vogels of Amazon.  His talk covered Amazon’s growth and the new services they offer including EC2.  He announced that EC2 now supports persistent storage, which is a huge improvement, but doesn’t quite solve all of the problems.

Testing PHP/MySQL Applications with PHPUnit/DbUnit

I’ve never been big into testing, but I’m trying to change that.  Sebastian Bergmann, the author of PHPUnit Pocket Reference (free online version), talked about PHPUnit and DbUnit and why I should use them.  Installing PHPUnit is extremely simple if you have pear installed:

pear channel-discover pear.phpunit.de
pear install phpunit/PHPUnit

Once installed, just require PHPUnit:

// php
require_once 'PHPUnit/Framework.php';

He just scratched the surface on writing unit tests. One thing he pointed out was using CruiseControl for automated testing. What’s really cool is you can fire off CruiseControl from Subversion commit hooks. If the testing fails, CruiseControl can send an email with the results and who is to blame.

Practical MySQL for Web Applications

Domas Mituzas of MySQL and Wikipedia fame gave a good talk that covered practical design of web applications. The talk covered simple stuff, so I didn’t learn a whole lot. Nevertheless, Domas sometimes says some funny things that make the talk enjoyable.

EXPLAIN Demystified

Baron Schwartz gave a talk about the EXPLAIN statement. EXPLAIN is run by prepending the word EXPLAIN to your SELECT statements. It only works on SELECT statements. When the query is run, it outputs an execution plan.

After running through the output of the EXPLAIN statement, he showed us mk-visual-explain which is one of the tools in Maatkit. It is a neato command line tool that takes the EXPLAIN output and reformats it as a tree structure. It’s a great way to visualize the execution plan. Now if only there was a GUI version…

Upgrading to Elegant Versatile Database Architecture using PHP5 Data Objects

This talk was given by Sigurd Magnusson of SilverStripe and covered PDO. I already researched and used PDO, so it was mostly review.

After talking to some of the other people at the conference, I’ve been seriously thinking of moving away from PDO and using MySQL specific functions because they expose some *really* cool debugging and profiling information.

Exploring Amazon EC2 for Scale-out Applications

The thought of EC2 sounds really cool. The ability to create a server instance and host your stuff on it within minutes is sweet. Need more servers, no problem, add another instance. The speakers, Morgan Tocker of MySQL and Carl Mercier of Defensio, talked about their experience with EC2.

There are some serious data and management issues. Until the other day, there wasn’t any kind of persistent storage, meaning when the server went offline, you lost all your data. Now you can mount a drive that persists across restarts. But one issue for critical business transactions is how and when data is written to disk. Is the data written immediately to disk or is buffered in the kernel or in some RAID card’s cache?

Another issue they ran into is when a new machine is created, there’s remnants of the previous machine’s instance’s data. So they need to zero out the drive which takes 5 hours on single instance.

What I took away from the talk is EC2 is great if your app is simple and relies on 3rd party services (i.e. Facebook, Google, etc) that are more reliable than EC2.

Service Oriented Architecture with PHP and MySQL

Joe Stump, a PHP hacker at Digg, gave a talk about SOA. It wasn’t as much about “web services” as it is managing tasks and processing them asynchronously.

After talking to Joe, he highly recommended Gearman to manage tasks. From the Gearman site: “Gearman is a system to farm out work to other machines, dispatching function calls to machines that are better suited to do work, to do work in parallel, to load balance lots of function calls, or to call functions between languages.”

So, if a user uploads an image, you can add the task of resizing the image to a backend processing mechanism. This allows for a responsive front-end for the user.

Joe, along with Chris Goffinet, are working on netgearman which is a PEAR package for interfacing with Gearman.

Memcached Hackathon BOF

This was a birds of a feature session where a bunch of people informally got together to discuss all things memcached. Patrick Galbraith of Grazr showed off Memcached Functions for MySQL. This is super cool. It allows you to set and get data in memcached within your SQL code via user defined functions.

So instead of pulling data from the DB to the app, then pushing it to memcached, you can just have a trigger or stored procedure store the value directly to memcached. One caveat is when you rollback a transaction, it won’t unset the value from memcached.

There was some discussion about the memcached MySQL storage engine. After listening to them discuss it, I have to wonder if it is really worth it. It acts like a distributed memory table, except when a server in a cluster goes down, it will affect all the other servers.

The second and last tutorial of Monday was Memcached and MySQL: Everything you need to know by Brian Aker and Alan Kasindorf.

The talk was mainly about memcached and libmemcached and less on MySQL. That’s OK since I have been meaning to learn more about memcached’s internals.

Alan and Brian discussed the slab allocator, protocol, internal hash table, LRU (least recently used), and threading. The slab allocator is the name of memcached memory allocator. The LRU keeps track of the age of each slab. memcached uses a consistent hash algorithm for the slabs to be located quickly and supports dynamically adding new servers to the pool. One thing that is cool about the hash table is it is pluggable and you can choose a different algorithm to meet your needs.

memcached’s protocol is ascii based, similar to HTTP, however they are in the process of finishing up a binary protocol which should have less overhead and better performance.

The current architecture is threaded and scales OK on machines with 4-8 cores, but when 16-32 core servers come out, memcached will not scale as well. Future versions will be improving threading support and scale better on larger machines.

Brian talked about the libmemcached a bit which is a memcached client library written in C. The API looks pretty easy as it uses very similar concepts and naming as other higher level client APIs.

One thing that Brian said that stood out is we should move away from synchronous actions and towards asynchronous event. It was a very interesting talk and Brian definitely knows what he’s talking about.