Read the original article at Make MySQL clustering work for you

We’ve told you all about MySQL mult-master replication’s limitations. If you write to two masters it is bound to fail for myriad reasons. Now what? Do what the pros do that’s what. A. Don’t write to both masters Using multi-master replication works great as long as you do so in active-passive mode. Never write to [...]

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Related posts:

Limitations of MySQL row-based replication

No tools to reconcile MySQL with two

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In the first part of this article we examined the types of conflicts and their causes. In this part, we will analyse some of the methods available to deal with conflicts.

Pessimistic locking (or: conflicts won't happen)

Applicability: synchronous clusters with 2pc

We've covered this topic in the previous article, but it's worth repeating. If you use a synchronous cluster, you don't have conflicts. For example, MySQL Cluster ensures consistent data with updates coming from different nodes. However, MySQL Cluster is not a replacement for a MySQL server, and it has severe limitations.

Optimistic locking

Applicability: synchronous clusters without 2pc (Galera)

Conflicting transactions proceed on different

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The Percona Live MySQL Conference and Expo 2013 is almost 1 month away. It's time to start planning, set the expectations, and decide what to attend. This post will give a roundup of some of the sessions that I recommend attending and I look forward to.

First, the unexpected!

After much talk and disbelief, here they come! Oracle (http://www.mysql.com) engineers will participate to the Percona Live conference. This is wonderful! Their participation was requested by the organizers, by the attendees, and by community advocates, who all told the Oracle management how important it is to be in this conference. Finally, they have

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Stating the problem.

In my job, I do a lot of testing. And no matter how much organized we try to be, we end up with fewer machines than we would need to run all the tests that we want.

For some tasks, we can run MySQL Sandbox, and get the job done. But sometimes we need to make sure that applications and systems work well across the network, and we need to install and run systems on separate servers.

However, when you test replication systems, and every cluster takes three or four servers, you run our of available hosts very quickly. So you decide to use the clusters that are dedicated to automated testing to also run your own manual tests. Soon you realize that the tests that you are running manually are clashing with the automated ones, or with the ones that your colleagues are running.

A simple solution

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Tungsten Replicator version 2.0.6 was released today.

You can get both the binaries and the source code at the project's downloads page.

This release contains many bug fixes, and various improvements. All of them are listed in the Release Notes. The most interesting ones are the improvement in multi-master topologies. Using this release with star topologies you will get less traffic than before, because we have reduced some duplication of transaction history logs that were sent between servers.

And speaking of multi-master topologies, this release includes the cookbook recipes mentioned in this blog

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I have been asked many times to provide an easy way of deploying fan-in and star schema replication schemas. So far, I have been delayed by more pressing duties.

Now the time has come. Since we are about to release a new version of Tungsten Replicator, I made the effort of putting together the steps for an easy deployment.

Recipes

The package (with downloads and svn code available at Tungsten-Replicator Toolbox) includes some juicy goodies. There are recipes to install.

• Master/slave, the classic replication topology. Nothing fancy, but with the tools mentioned in the next section, it becomes as valuable as the other topologies.
• All-masters. This is the Tungsten no-SPOF topology. Every node is a master,

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Working with replication, you come across many topologies, some of them sound and established, some of them less so, and some of them still in the realm of the hopeless wishes. I have been working with replication for almost 10 years now, and my wish list grew quite big during this time. In the last 12 months, though, while working at Continuent, some of the topologies that I wanted to work with have moved from the cloud of wishful thinking to the firm land of things that happen. My quest for star replication starts with the most common topology. One master, many slaves.

Fig 1. Master/Slave topology

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One lesson learned in more than two decades working in this industry is that most of the IT professionals are impatient, want to achieve results immediately, and, most importantly, they don't read documentation. Much as the average geek is happy to answer many requests with a dismissive RTFM, the same geeks are not as diligent when it comes to learning about new or updated technologies. For this reason, there is a kind of documentation that is very much appreciated by busy and impatient professionals: cookbooks. And I am not talking about food. Geeks are not known for being cooks (1) and they like fast food. I am talking about collection of technical recipes, short articles where a problem is briefly stated, and a direct solution is shown. Working with Tungsten Replicator, I am constantly amazed at all the things you  [Read more...]

About a month ago I needed to compare tens of thousands of tables in hundreds of databases between a few different servers. The obvious choice was, mk-table-checksum! The only problem was, that the tool needs to know the minimum and maximum value of the column by which each table is to be subdivided into chunks and checksummed. This select min(col), max(col) from table locks all write operations on the table and on a big table it meant downtime.

Looking at the source it was clear we could make mk-table-checksum run the select min(col), max(col) from table on the read-only slave and use the values to checksum the master.

It was subtle code changes in function:
get_range_statistics adding

my $cxn_string_dc = “DBI:mysql:;host=slavehost;port=3306;mysql_read_default_group=client”;
my $user = ‘user’;

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MySQL DBAs and developers: oil your fingers and get ready to experience a new dimension of data replication. I am pleased to announce that Continuent has just released Tungsten Replicator 2.0, an open source data replication engine that can replace MySQL native replication with a set of advanced features.
A note about the source code. The current version of Tungsten Replicator available in the web site is free to use, but it is not yet the open source version. We need a few weeks more to extract the code from the enterprise tree and make a new build. But we
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