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Percona XtraDB Cluster: SElinux is not always the culprit !

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 …

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How to STOP SLAVE on Amazon RDS read replica

We are doing a migration from Amazon RDS to EC2 with a customer. This, unfortunately, involves some downtime – if you are an RDS user, you probably know you can’t replicate an RDS instance to an external server (or even EC2). While it is annoying, this post isn’t going to be a rant on how RDS can make you feel locked in. Instead, I wanted to give you a quick tip.

So here’s the thing – you can’t stop replication on RDS read replica, because you don’t have (and won’t get) privileges to do that:

replica> STOP SLAVE;
ERROR 1045 (28000): Access denied for user 'usr'@'%' (using password: YES)

Normally, you don’t want to do that, however we wanted to run some pt-upgrade checks before we migrate and for that we needed the read replica to stop replicating. Here’s one way to do it:

WARNING! …

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SFTP virtual users with ProFTPD and Rails: Part 1

I recently worked on a Rails 3.2 project that used the sweet PLupload JavaScript/Flash upload tool to upload files to the web app. To make it easier for users to upload large and/or remote files to the app, we also wanted to let them upload via SFTP. The catch was, our users didn't have SFTP accounts on our server and we didn't want to get into the business of creating and managing SFTP accounts. Enter: ProFTPD and virtual users.

ProFTPD's virtual users concept allows you to point ProFTPD at a SQL database for your user and group authentication. This means SFTP logins don't need actual system logins (although you can mix and match if you want). Naturally, this is perfect for dynamically creating and destroying SFTP accounts. …

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Innodb Read Only Mode

Offers user a easy way to keep data write protected on RW and allows server to run even on RO media.

The Queen of Evil is back … and she wants your MySQL database skills!

She hired the 400+ original MySQLers … and sets out to hire the SkySQLers of tomorrow! Boel Larsen blogs about open positions & life at SkySQL - and wants you to join the fun!

Those of you who know me also know that I spent over six years working for MySQL HR (for another couple of years I stayed on with Sun).  I joined as employee thirty-something, so running HR meant that I was more or less involved with hiring all of the 400 or so employees who joined after me. I knew pretty much everyone by name.

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Gluh on InnoDB extended secondary keys

Sergey Glukhov (Gluh) recently wrote an interesting blog about InnoDB secondary key improvements in MySQL 5.6. His blog isn't aggregated to planet.mysql.com but certainly deserves some attention. 
Here it is: InnoDB, extended secondary keys.

Percona Toolkit Webinar followup Q&A

First, a thank you to everyone who attended the webinar Today, I appreciate your time and nice comments. As promised, here are answers to questions that couldn’t be answered during the talk:

 

Q: How do you install the tools?

The manual has full details, but it’s important to know that the latest release for every tool is also available for direct download in a url like this: http://www.percona.com/get/<tool-name>. I use this a lot when I just need a specific tool and I’m working on a server without the toolkit installed.

Q: How to make the tools connect to MySQL

The slides are now available here, and slide 7 provides a basic introduction to Data Source Names, with more details available …

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MySQL learning resources

There are a few interesting learning resources recently created by activists in the MySQL community. I just wanted to link to them to spread the word. They are free and if you've been looking for a way to learn more about MySQL, you should have a look at these.

MySQL Marinate

This is something I haven't really seen done before (for MySQL): a virtual self study group. It is based on the idea of everyone reading the same book, and I assume Sheeri will then facilitate some commentary on what your read. Sheeri mentioned this in a blog post earlier, but yesterday I went to check the signup page and wow - there are already 117 (or 76, depending on whether you look to the left or to the right) students registered!

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Super Python: three applications involving IRC bot master, MySQL optimization, and Website stress testing.

In my ongoing efforts to migrate my fun side projects and coding experiments from SVN to Git I’ve come across some of my favorite Python based apps – which are all available in their respective repos on BitBucket, as follows:

IRC Bot Commander

  • What it does: it’s an IRC bot that takes commands and does your bidding on whichever remote server the bot is installed on.
  • How it does it: the bot runs on whatever server you install it on, then it connects to the IRC server and channel you configured it to connect to and it waits for you to give it commands, then it execs the commands and returns the output to your IRC chat window.

MacroBase – MySQL Analytics

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MySQL Wins the Linux Journal Readers Choice Award for Best Database 2012

MySQL has once again won the Linux Journal Readers Choice Award for Best Database 2012. Thanks to all who votes and all who use MySQL.


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