In the last 10 years I have worked a lot with replication systems, and I have developed a keen interest in the topic of multiple masters in a single cluster. My interest has a two distinct origins:

• On one hand, I have interacted countless times with users who want to use a replication system as a drop-in replacement for a single server. In many cases, especially when users are dealing with applications that are not much flexible or modular, this means that the replication system must have several points of data entry, and such points must work independently and in symbiosis with the rest of the nodes.
• On the other hand, I am a technology lover (look it up in the dictionary: it is spelled geek), and as such I get my curiosity stirred whenever I discover a new possibility of implementing multi-master systems.

The double nature of this professional curiosity makes me sometimes forget that the …

Busy database-backed websites often hit scalability limits in the database first. In tuning MySQL, one of the first things to look at is the max_connections parameter, which is often too low. (Of course another thing to look at is appropriate fragment caching in your app server, HTTP object caching in your web server, and a CDN in front of it all.)

When using MySQL 5.5 from Oracle's RPMs through cPanel (MySQL55-server-5.5.32-1.cp1136) on RHEL 5.10 x86_64, there is an interesting problem if you try to increase the max_connections setting beyond 214 in /etc/my.cnf. It will silently be ignored, and the limit remains 214:

mysql> show variables like 'max_connections';
+-----------------+-------+
| Variable_name   | Value |
+-----------------+-------+
| max_connections | 214   |
+-----------------+-------+
1 row in set (0.00 sec)

The problem is that the maximum number of open files allowed is too small, by default 1024, to …

The MySQL Utilities Team is pleased to announce the latest GA release of MySQL Utilities. This release includes a number of improvements for usability, stability, and a few enhancements. We have also included a performance upgrade for exporting, importing, and copying databases.

Improvements
The following highlights a few of the more significant improvements.

* mysqldbexport, mysqldbimport, and mysqldbcopy have multiprocessing support that allows for much improved performance
* mysqlfrm can now generate a .frm file with storage engine substitution
* Mac OS X packages added!
* mysqlserverinfo now includes the log files (error, general, slow)
* mysqlprocgrep can now search and kill processes by id
* mysqlmetagrep can now search the body of routines with the new --body option
* all utilities report license type with --version and --help
* all utilities have the new …

MySQL DBA skills are highly sought after in the market place. The MySQL for Database Administrators course is a highly popular course created by the MySQL experts to give you hands-on experience with tasks ranging from installing MySQL to investigating different replication scenarios and planning for disaster recovery.

You can take this 5-day instructor-led course as a:

• Live-Virtual Event: Take this class from your own desk - no travel required. Choose from a selection of events on the schedule to suit different timezones.
• In-Class Event: Travel to an education center to take this class. Below is a selection of the events already on the schedule for this course.

December 5, 2013 By Severalnines

Thanks to everyone who attended yesterday’s webinar; if you missed the sessions or would like to watch the webinar again & browse through the slides, they are now available online.

Thanks again to our speaker, Seppo Jaakola from Codership, the creators of Galera Cluster, for this in-depth talk on Galera Cluster Best Practices - Zero Downtime Schema Changes.

Webinar topics covered

• How to perform Zero Downtime Schema Changes
• 2 main methods: TOI and RSU
• Total Order Isolation: predictability and consistency
• Rolling Schema Upgrades
• pt-online-schema-change
…

So, after installing Workbench 6.0.7 on my pc, and playing around with the MySQL Utilities that are included, I thought I’d do similar to what others have done (Thanks Tony D.) and share my experience on how I’ve used them. If you haven’t installed Workbench before, you might want to check your platform first: http://www.mysql.com/support/supportedplatforms/workbench.html.

So, even if you’re not using any of the recent versions and editions of Workbench (Utilities comes with all of them, Tools menu -> “Start Shell for MySQL Utilities“) you can just download the standalone scripts on a Linux machine. Flexibility being the name of the game again. …

So, after installing Workbench 6.0.7 on my pc, and playing around with the MySQL Utilities that are included, I thought I’d do similar to what others have done (Thanks Tony D.) and share my experience on how I’ve used them. If you haven’t installed Workbench before, you might want to check your platform first: http://www.mysql.com/support/supportedplatforms/workbench.html.

So, even if you’re not using any of the recent versions and editions of Workbench (Utilities comes with all of them, Tools menu -> “Start Shell for MySQL Utilities“) you can just download the standalone scripts on a Linux machine. Flexibility being the name of the game again. …

I took a quick look at MariaDB 10.0 single-treaded performance (simple read-only sysbench). One thing immediately leaps to the eye, and I thought it worthy of mention. It contains an important lesson about the use of synchronisation primitives and in particular "atomic operations" in MariaDB (and MySQL).

I am using the Linux perf tool on this sysbench command:

  sysbench --num-threads=1 --test=oltp --oltp-test-mode=simple --oltp-read-only --oltp-skip-trx

Look at the top offender in the output from perf report:

  1,54%  mysqld  mysqld               [.] set_thread_state_v1

The only thing this does is set a string for SHOW PROCESSLIST (and the like) about what the thread is doing. And we are spending a whopping 1.5% of the total time doing this.

And why? That becomes clear when looking at the disassembly …

Users are complaining about slowness in your system, MySQL load is always high… The more your database has access, the more it may get slow or worse: slowness even if it is running with low load. You are starting to get desperate! The consequences of slowness and high load are disastrous: If your site is slow,... Read More

The post MySQL Performance and Tuning Best Practices appeared first on Devops for Dummies.

November 4, 2013 By Severalnines Percona Live London MySQL Conference - 11-12th November, 2013

We’re particularly excited about this year’s Percona Live London MySQL Conference. The line-up of speakers & topics looks excellent and it’s good to see speakers from Oracle, Percona, the MariaDB Foundation (amongst others) scheduled at the same event. It demonstrates not just the diversity of the ever broadening MySQL ecosystem, but also the fact that there really is room for everyone to contribute, participate in and advance MySQL in manifold directions while still retaining a certain amount of uniformity.

And this is how we will be contributing to the event ...

Talk - MySQL Cluster Performance Tuning By Johan Andersson, CTO & Co-Founder, Severalnines

Correct tuning of MySQL NDB Cluster can have dramatic impact on …