I have recently been involved in diagnosing the reasons behind OOM invocation that would kill the MySQL server process. Of course these servers were primarily running MySQL. As such the MySQL server process was the one with the largest amount of memory allocated.

But the strange thing was that in all the cases, there was no swapping activity seen and there were enough pages in the page cache. Ironically all of these servers were CentOS 6.4 running kernel version 2.6.32-358. Another commonality was the fact that vm.swappiness was set to 0. This is a pretty much standard practice and one that is applied on nearly every server that runs MySQL.

Looking into this further I realized that there was a change introduced in kernel 3.5-rc1 that altered the swapping behavior when “vm.swappiness=0″.

Below is the description of the commit that changed “vm.swappiness=0″ behavior, together with the diff:

$ git show …

Hey, thanks for the blog article.Really looking forward to read more. Much obliged.

MySQL SystemQA: MySQL Fabric Setup using ndb Cluster

MySQL Fabric is an open-source solution released by the MySQL Engineering team at Oracle. It is 
an extensible and easy to use system for managing a MySQL deployment for Sharding  and
High-availability.

To ensure/provide resilience to failures, MySQL Fabric manages servers in groups and deploy 
High Availability. MySQL Fabric also supports Sharding, which is used to scale out a large 
databases. Sharding setup handles the increasing demand for read loads and also handles the 
increasing write loads. The database/table are shared across different servers, where each shard
contain a fragment of the data.



A Fabric node is Fabric Process + State Store (which is a MySQL Server).As MySQL Fabric 
manages such a valuable information for server farms and scaling of database, using single 
machine to handle the MySQL Fabric node is not a good solution. Thus we need to come up 
with a solution that …

It’s quite exciting to see the amount of MariaDB books out there (first GA release of software: February 2010).

From left-to-right:

1. MariaDB Crash Course (August 2011)
2. Getting Started with MariaDB (October 2013)
3. …

Benchmarking lets you test how a system responds when it is given work to do, and removes the guesswork from your performance tuning efforts. The workloads you use when benchmarking are very different from real life deployments, which can be extremely variable. If you remember this, benchmarking is extremely useful, enabling you to measure current performance and determine the performance impact of any changes. Such changes could be the addition of new hardware or opening up your application to more users.

Benchmarking is one of the topics that you can learn more about by taking the MySQL Performance Tuning course. You can take this course in the following formats:

• Training-on-Demand: Start training within 24 hours of registration, following lecture …

I was listening to a conversation recently and heard an experienced engineer express an interesting point of view on joins and key-value databases. I don’t entirely agree with it. Here’s why.

First, the opinion. If I may paraphrase, the discussion was something like this:

• With experience in building distributed systems, one learns to avoid JOIN.
• Therefore, much of the work of JOIN is done in the application instead of the database.
• Access to the database is usually reduced to simple primary-key lookups.
• Therefore, a key-value store is as good a choice as a relational database.

I’m simplifying, because the speaker actually suggested that MySQL makes a really good database for primary-key lookups as well.

The place I would differ slightly is on the last bullet point. It really depends on which key-value store you choose. The subtlety I’d suggest to …

There was some code in Shard-Query 2.5 that was not protected by an if() clause, and subsequently caused queries without a GROUP BY to generate a warning.  The warnings didn’t cause the test suite to fail and I missed them.   I updated the Shard-Query 2.5 binary so please redownload it if you get a warning about GROUP BY when not using GROUP BY in a query.

So I recently realized that I have not yet talked much about MySQL partitions.
Many good blog posts on MySQL partitions already exists and I have listed a few below.

• http://glynndba.blogspot.com/2009/10/rolling-time-based-partitions.html
• http://www.mysqlperformanceblog.com/2010/12/11/mysql-partitioning-can-save-you-or-kill-you/
• http://datacharmer.blogspot.com/2010/05/two-quick-performance-tips-with-mysql.html
• …

It's now 3 weeks since the MariaDB & MySQL community day in Santa Clara.

Thanks everyone for coming!

Personally I think it was a success, especially considering the short
time we had to put it together! 11 great speakers and 100+ participants.

We had a small issue with the camera that we used to record all talks: The slides are not very visible. We have been working on editing the videos for all talks to fix this and will update the conference page with both slides and videos for the talks as soon as the editing is finished. The first video is already available! Hope you like it!

We plan to have another MariaDB & MySQL community day in mid November in Florida and another one in Europa after the summer.

Please contact me at …

Taxonomy upgrade extras: myenvoperationMySQL Operationsmulti instanceconsolidation

FromDual has the pleasure to announce the release of the new version 1.0.3 of its popular MySQL, MariaDB and Percona Server multi-instance environment MyEnv.

The majority of improvements happened on the MySQL Backup Manager (mysql_bman) utility.

You can download MyEnv from …