March 3, 2014 By Severalnines

Hybrid replication, i.e. combining Galera and asynchronous MySQL replication in the same setup, became much easier with MySQL 5.6 and GTID. Although it was fairly straightforward to replicate from a standalone MySQL server to a Galera Cluster, doing it the other way round (Galera → standalone MySQL) was a bit more challenging. At least until MySQL 5.6 and GTID. 

There are a few good reasons to attach an asynchronous slave to a Galera Cluster. For one, long-running reporting/OLAP type queries on a Galera node might slow down an entire cluster, if the reporting load is so intensive that the node has to spend considerable effort coping with it. So reporting queries can be sent to a standalone server, effectively isolating Galera from the reporting load. In a belts and suspenders approach, an …

While user bug reports are the most important ones, there is a category of external reporters which I historically have a special interest in and great expectations for: entry-level testers. I was one, trained some, interviewed many, had a few hired, and have always wanted someone to wake them up and get going before it’s too late.

There is no secret that quality control is not as glamourous as other IT specialities, and there are no famous (or maybe any) student programs for testers. Usually people come into testing because it is deceptively open for newbies, planning to obtain a few points for a CV and switch either to development or to project management as soon as they can. Most do, a few stay.

It creates a vicious cycle. Since this is a well-known pattern, employers hire testers without experience not to teach …

February 27, 2014 By Severalnines

Stockholm MongoDB User Group Meetup: “MongoDB and Hadoop” Monday, March 3, 2014 starting @ 5:00 PM

Join us next Monday as we host the Stockholm MongoDB User Group Meetup in Kista, or the Wireless Valley as it is also referred to. 

Our very own Vinay Joosery will be speaking about how to best automate the management & deployment of database clusters, specifically MongoDB clusters though the same principles apply for MySQL, MariaDB and Percona XtraDB based clusters. Henrik Ingo of MongoDB will be talking about Analytics with MongoDB & Hadoop. And Jim Dowling, a Senior Researcher at the Swedish Institute of Computer Science, will talk about a Hadoop PaaS platform. 

So whether you’re from the MySQL or NoSQL world, there’ll be plenty of good content here to walk away with in addition to getting …

The MariaDB developers have made several releases in the past week. Rather than post about all of them separately, we decided to combine them into one post. Details for each release are available on their individual Release Notes and Changelog pages.

MariaDB 5.5.36

First up is MariaDB 5.5.36. This is a Stable (GA) release. Apart from general maintenance, bug fixes, and updates, TokuDB is now included in RPM packages for CentOS 6 on x86-64.

Download MariaDB 5.5.36

Release Notes Changelog …

MaxScale is a Proxy for the MySQL protocol built with a modular architecture. The underlying concept of modules allows to extend the MaxScale proxy services. The current version implements Read Write splitting and Connection Load Balancing. Internally MySQL queries go through a SQL parsing phase. This gives MaxScale great capabilities regarding queries routing.

So if [...]

I’m happy to announce that a new version of the MariaDB Audit Plugin is available. Version 1.1.5 can be downloaded here. As you can see the Audit Plugin is available from SkySQL, who has developed the plugin.

However, now with the Audit Plugin being GA for a couple of months since 7th of November last year and customers using it in production, SkySQL has decided to contribute the Audit Plugin to the MariaDB project and I’m happy to tell you that starting from MariaDB versions 5.5.37 and 10.0.9 the Audit Plugin will be included by default. Notice that these versions of MariaDB aren’t yet released.

The MariaDB Audit Plugin introduces the capabilities of tracking user access to data. By having the Audit Plugin available by default in MariaDB, all users can easily set up tracking in their own systems and follow in real time who’s doing what in …

If you have followed this series of blogs (Introduction in part 1, Setting up the cluster in part 2 and Installing and configuring MaxScale in part 3), you should now have MaxScale up and running on a Cluster using MariaDB Replication. But as I said when I left off in Part 3, there is more to it.

To begin with, let's look at how the replication system works. Let's insert some more data through MaxScale, this should end up with the master and the replication system will handle making this available on the slaves. So on the Client machine (192.168.0.167), logged in a root, do:
# mysql -h …

Today I looked at the MariaDB Release Candidate wondering how my earlier predictions came out.

I predicted, for "roles":

For all of the bugs, and for some of the flaws, there's no worry -- they'll probably disappear.

In fact all the bugs are gone, and I belatedly realized (after some gentle nudges from a MariaDB employee) that some of the flaws weren't flaws.
The inability to grant to PUBLIC still troubles me, but it looks like roles are ready to roll.

I predicted for "mroonga":

At the time I'm writing this, MariaDB 10.0.8 doesn't have mroonga yet.

In other words, I thought it would be in 10.0.8. It was not to be, as another …

I blogged a couple of weeks ago about my upcoming MySQL/Hadoop talk at SCaLE 12X. Unfortunately I had to cancel. A few days after writing the article I came down with an eye problem that is fixed but prevents me from flying anywhere for a few weeks. That's a pity as I was definitely looking forward to attending the conference and explaining how Tungsten replicates transactions from MySQL into HDFS.

Meanwhile, we are still moving at full steam with Hadoop-related work at Continuent, which is the basis for the next major replication release, Tungsten Replicator 3.0.0. Binary builds and documentation will go up in a few days. There will also be many more public talks about Hadoop support, starting in April at …

Lets start by considering a scenario where records are being inserted in a single auto-increment table via different nodes of a multi-master cluster. One issue that might arise is ‘collision’ of generated auto-increment values on different nodes, which is precisely the subject of this article.

As the cluster is multi-master, it allows writes on all master nodes. As a result of which a table might get same auto-incremented values on different nodes on INSERTs. This issue is discovered only after the writeset is replicated and that’s a problem!

Galera cluster suffers with the similar problem.

Lets try to emulate this on a 2-node Galera cluster :

1) On node #1:

MariaDB [test]> CREATE TABLE t1(c1 INT AUTO_INCREMENT PRIMARY KEY, c2 INT)ENGINE=InnoDB;
Query OK, 0 rows affected (0.07 sec)

MariaDB [test]> START TRANSACTION;
Query OK, 0 rows affected (0.00 sec)

MariaDB [test]> INSERT INTO t1(c2) VALUES (1);
Query …