The Percona Live MySQL Conference and Expo begins next Monday and runs April 22-25, 2013. Attendees will see great keynotes from leaders in the industry including representatives from Oracle, Amazon Web Services, HP, Continuent, and Percona. They can also participate in thought provoking Birds of a Feather sessions on Tuesday night and the Wednesday night Community Networking Reception will be fun and entertaining with the presentation of the Community Awards and the Lightning Talks.

If you cannot attend the entire Percona Live MySQL Conference but want to take advantage of the keynotes, BOFs, and Community Networking …

I wanted to do some experimentation with Percona XtraDB Cluster (Galera) and I didn't want to use virtual machines. I'm already using MySQL Sandbox for many other projects so that's the natural choice.

I've downloaded the tarball for Percona XtraDB Cluster 5.5.29 and I've extracted it to ~/opt/mysql/5.5.29-pxc.

Then I've installed 3 nodes:
make_sandbox 5.5.29-pxc -- --sandbox_port 4551 \
--sandbox_directory msb_5_5_29-pxc01 

make_sandbox 5.5.29-pxc -- --sandbox_port 4552 \
--sandbox_directory msb_5_5_29-pxc02 

make_sandbox 5.5.29-pxc -- --sandbox_port 4553 \
--sandbox_directory msb_5_5_29-pxc03 

But when I try to start a node this error happens:
130327 14:21:03 [Note] WSREP: wsrep_load(): loading provider library '/home/dvee
den/mysql/5.5.29-pxc/lib/libgalera_smm.so'
130327 14:21:03 [ERROR] WSREP: wsrep_load(): …

Percona CEO Peter Zaitsev leads a track at Percona MySQL University in Raleigh, N.C. on Jan. 29, 2013.

Percona MySQL University, Toronto is taking place this Friday and I’m very excited about this event because it is a special opportunity to fit a phenomenal number of specific and focused MySQL technical talks all into one day, for free.

Over the course of the day we will cover some of the hottest topics in the MySQL space. There will be talks covering topics like MySQL 5.6, MySQL in the Cloud and High Availability for MySQL, as well as Percona XtraDB Cluster for MySQL. We have talks planned for nearly every …

I’m pleased to announce that Oracle is sending some of their top technical people to speak at the Percona Live MySQL Conference and Expo. The conference takes place April 22-25, 2013 at the Santa Clara Convention Center and Hyatt Santa Clara.

Tomas Ulin, VP, MySQL Engineering for Oracle, will present an invited keynote talk on “Driving MySQL Innovation” during the Tuesday morning opening keynotes. With the recent release of MySQL 5.6, conference attendees will hear about the latest developments of this major MySQL release.

In addition to Tomas, Oracle MySQL technologists will also lead three breakout …

Accessing Percona XtraDB Cluster nodes in parallel with MySQL asynchronous calls

This post is followup to Peter’s recent post, “Investigating MySQL Replication Latency in Percona XtraDB Cluster,” in which a question was raised as to whether we can measure latency to all nodes at the same time. It is an interesting question: If we have N nodes, can we send queries to nodes to be executed in parallel?

To answer it, I decided to try a new asynchronous call to send a query to MySQL using a new MySQLnd driver for PHP. In this post I’ll only show how to make these calls, and in following posts how to measure latency to all nodes.

PHP does not provide …

Investigating MySQL Replication Latency in Percona XtraDB Cluster

I was curious to check how Percona XtraDB Cluster behaves when it comes to MySQL replication latency — or better yet, call it data propagation latency. It was interesting to see whenever I can get stale data reads from other cluster nodes after write performed to some specific node. To test it I wrote quite a simple script (you can find it in the end of the post) which connects to one node in the cluster, performs an update and then immediately does the read from second node. If the data has been already propagated — good, if not we’ll continue to retry reads until it finally propagates, and then measure the latency. This is used to see whenever application …

Percona is glad to announce the release of Percona XtraDB Cluster on January 30th, 2013. Binaries are available from downloads area or from our software repositories.

Bugs fixed:

• In some cases when node is recovered variable threads_running would become huge. Bug fixed #1040108 (Teemu Ollakka).
• Variable wsrep_defaults_file would be set up to the value in the last configuration file read. Bug fixed by keeping the value found in the top configuration file. Bug fixed …

If you are using SElinux, you should know that it’s advised to disable it to avoid issue with PXC. Generally the communication between your nodes doesn’t work properly and a node having SElinux enabled won’t be able to join the cluster.

So when a node doesn’t join the cluster where it should, my first reflex is to have a look at audit.log. But recently I faced another problem: the node joined the cluster but SST failed (whatever which method was used, discarding skip).

I checked SElinux and it was of course disabled, then I add some debug information in the SST script but it seemed that the script was never launched. And this time the culprit is called : AppArmor !

Percona doesn’t provide any AppArmor profile for PXC, but it seems that on this server (Ubuntu TLS), a previous version of MySQL was installed and then removed but the AppArmor profile was still present.

So if you use apparmor (or if you …

How easy is it to identify and debug Percona XtraDB Cluster replication problem ?

If you are using PXC, you may have already seen in your datadirectory several log files starting with GRA_

Those files correspond to a replication failure. That means the slave thread was not able to apply one transaction. For each of those file, a corresponding warning or error message is present in the mysql error log file.

Those error can also be false positive like a bad DDL statement (DROP a table that doesn’t exists for example) and therefore nothing to worry about. However it’s always recommended to understand what’s is happening.

As the GRA files contain binlog events in ROW format representing the failed transaction this post explains how to proceed.

The first step to be able to analyze your GRA files is to add a binlog header to the file.
You can download one here : …

The Web And PHP Magazine just published an article describing Percona XtraDB Cluster written by Liz van Dijk and Kenny Gryp. It is a pretty high-level introduction to the technology, so definitely give it a read if you’ve been wanting to give it a closer look.

Go to their website http://www.webandphp.com and download Issue number 9 for free!