As Giuseppe Maxia recently posted we released Tungsten Replicator 2.0.4 this week.  It has a raft of bug fixes and new features of which one-line installations are the single biggest improvement.  I set up replicators dozens of times a day and having a single command for standard cluster topologies is a huge step forward.  Kudos to Jeff Mace for getting this nailed down.

So what's next?  You can get see what we are up to in general by looking at our issues list.  We cannot do everything at once, but here are the current priorities for Tungsten Replicator 2.0.5.

• Parallel replication speed and robustness. …

When you set-up the same software several times (for you or for your customers), you want that software to install quickly and reliably, and you are generally happy when everything works as expected.
In this context, a failing installation is when the installation process exits unexpectedly, and you are left with an error message and the prospect of looking at the manual to find out what was it.

A failing installation is unpleasant, you'd say, and I concur. But do you know what's more unpleasant than a failing installation? It's an installation that succeeds, only to fail silently the first time you try using the application.

Looking at this enhanced definition, it is no surprise that I assert to find happiness in failure. And I have practical reasons for my claim. When I first tried Tungsten Replicator installation, it succeeded. And to my …

Probably …

I’ve been following the development of Tungsten Replicator for quiet some time now, and recently was fortunate enough to find the time to take a look at the product in more detail. If you haven’t heard of Tungsten Replicator yet, it’s an open source database replication engine that can be used to complement or completely [...]

MySQL Replication is a powerful tool and it’s hard to find a production system not using it. On the other hand debugging replication issues can be very hard and time consuming. Especially if your replication setup is not straightforward and you are using filtering of some kind.

Recently we got an alert from our monitoring system that replication stopped on production slave with the following error:

Can't find record in 'some_table', Error_code: 1032;
handler error HA_ERR_KEY_NOT_FOUND;
the event's master log binlog.000011, end_log_pos 735766642

This means that a ROW-based replication event was going to be applied on slave, but could not find the row it was supposed to be applied to. This is something I like about ROW format — it allows you to catch such data synchronization issues right away. In this particular case MIXED format was used, but if this event was written in STATEMENT format, slave would just apply it …

Earlier this month I published an article on this blog describing the system of record approach to multi-master replication.  As mentioned in that article my colleagues and I at Continuent have been working on improving Tungsten to make system of record design patterns easier to implement.  This article describes how to set up system of record using Tungsten Replicator shard filters, which are a new feature in Tungsten 2.0.4.  By doing so we will create a multi-master configuration that avoids replication loops and transaction conflicts.  On top of that, it is quite easy to set up.

There are many possible system of record patterns depending on how many schemas are shared and across how many masters.  The following diagram …

My recent post on setting up Tungsten parallel replication in a hurry got a lot of hits, though to be fair it was probably not the great writing but the fact that at least one popular MySQL blog posted a link to it.  (Thanks, we like you guys too.)  Anyway, I would like to invite anybody who is interested in parallel replication to attend a webinar on Thursday September 1st at 10am PDT to cover installing and using Tungsten.  It's straight-up technical talk to help you start quickly. 
Bringing up Tungsten on an existing MySQL slave only takes a few minutes, so once we have that out of the way I will explain how Tungsten works inside and show you some …

Multi-master database systems that span sites are an increasingly common requirement in business applications.  Yet the way such applications work in practice is not quite what you would think from accounts of NoSQL systems like Cassandra or SQL-based systems like Oracle RAC.  In this article I would like to introduce a versatile design pattern for multi-master SQL applications in which individual schemas are updated in a single location only but may have many copies elsewhere both locally as well as on other sites.  This pattern is known as a system of record architecture.  You can build it with off-the-shelf MySQL and master/slave replication.

Let's …

Why This Post
While testing Yoshinori Matsunobo's MHA agent I found that although the wiki has a very complete documentation, it was missing a some details. This article intends to close that gap and bring up some issues to keep in mind when you do your own installation. At the end of the article I added a Conclusions section, if you're not interested in the implementation details, but to read my take on the project, feel free to jump straight to the end from here.

My Test Case
Most of our production environments can be simplified to match the MHA's agent most simple use case: 1 master w/ 2 or more slaves and at least one more slave in an additional tier:

Master A --> …

A previous article on this blog described Tungsten parallel replication using on-disk queues.  On-disk queues are now more or less finished, and I just closed the covering issue for the feature.  The work is bug fixing and performance testing from here on out.  Speaking of performance, that looks fairly good.   A recent on-site test using production workloads showed 3.3X improvement over native MySQL replication while holding resources like memory down to much more reasonable levels than in-memory queues.  We have further optimizations on the way, so this should improve.

Now that parallel replication is working a lot better, what is it good for?  Here is a good start:  assuming your …