Release 1.2.2 of Tungsten Clustering is available on SourceForge as well as through the Continuent website.  The release contains mostly bug fixes in the open source version but there are also two very significant improvements of interest to all users.

• The manager and monitoring capabilities of Tungsten are completely integrated on the same group communications channel.  This fixes a number of problems that caused data sources not to show up properly in older versions.  
• We are officially supporting a new Tungsten Connector capability for MySQL called pass-through mode, which allows us to proxy connections by transferring network blocks directly rather than translating native request protocol to JDBC calls.  Our tests show that it speeds up throughput by as much as 200% …

I generally thought about MySQL replication as being quite low overhead on Master, depending on number of Slaves. What kind of load extra Slave causes ? Well it just gets a copy of binary log streamed to it. All slaves typically get few last events in binary log so it is in cash. In most cases having some 10 slaves are relatively low overhead not impacting master performance a lot. I however ran into the case when performance was significantly impacted by going from 2 to 4 slave on the box. Why ?

The reason was Master was having a lot of very small updates going on - over 15.000 transactions a second. Each time event is logged to the binary log all 4 threads feeding binary logs to the slave were to be woken up to send the update notification. With 4 slaves connected this makes 60.000 of threads being woken up sending some 60.000 packets (there may be some buffering taking place on TCP side merging multiple sends but still)

I guess …

Check out how Linden Labs, creators of the popular game Second Life, upgraded their MySQL database. The MySQL they use? Straight out of Debian! Of course, now, they’re running with the Percona patchset, against MySQL 5.0.84. Definitely a good read.

Its good to see Lars post about contributing to the MySQL replication & backup codebase. It sounds like the replication & backup team have decided that mentoring is the way to go – you get a “coach developer” if the idea is accepted. I like this very much, and sincerely hope it spreads to the rest of the server; it will help decentralise …

Being a MySQL DBA , one faces a common issue in replication environment -> Disk space issue on master, since the number of binary logs have increased. Now, one of the solution to this would be using expire_logs_days parameter in your mysql config file. But what if, the slave is lagging by few hours or if the slave is broken since few days and the binary logs are removed due to the parameter set. Whenever the salve comes up, it will go bonkers, knowing that the binary log where it last stopped no more exists.
I faced this issue a couple of times until I decided to automate it using a script. Herewith I am attaching the URL to my python script which can run regularly in cron. Features :

• Checks the slaves connected to the master (I have limit it to 3 for now.)
• Checks the last binary log file which is being used by the slave.
• …

Software-as-a-Service (Saas) is one of the main growth areas in modern database applications.  This topic has become a correspondingly important focus for Tungsten, not least of all because new SaaS applications make heavy use of open source databases like MySQL and PostgreSQL that Tungsten supports.

This blog article introduces a series of essays on database architectures for SaaS and how we are adapting Tungsten to enable them more easily.  I plan to focus especially on problems of replication and clustering relevant to SaaS—what are the problems, what are the common design patterns to solve them, and how to deploy and operate the solutions. I will also discuss how to make replication and clustering work better for these cases—either using Tungsten features that already exist or features we are designing.

I hope everything you read will …

2009 has been a big year for Tungsten. In January we had (barely) working replication for MySQL. It had some neat features like global IDs and event filters, but to be frank you needed imagination to see the real value. Since then, Tungsten has grown into a full-blown database clustering solution capable of handling a wide range of user problems. Here are just a few of the features we completed over the course of the year:

• Autonomic cluster management using business rules to implement auto-discovery of new databases, failover, and quick recovery from failures
  
• Built-in broadcast monitoring of databases and replicators
• Integrated backup and restore operations
  
• Pluggable replication management, proven by clustering implementations based on PostgreSQL Warm Standby and Londiste
  
• Multiple routing mechanisms to provide seamless failover and load balancing of SQL
…

Keeping a MySQL installation up and running can be quite tricky at times, especially when having many servers to manage and monitor. In the replication tutorials at the annual MySQL Users' Conference, we demonstrate how to set up replication appropriately and also how to handle various issues that can arise.

Many of these procedures are routine: bring down the server, edit the configuration file, bring the server up again, start a mysql client and add a user, etc.

It has always annoyed me that these procedures are perfect candidates for automation, but that we do not have the necessary interfaces to manipulate an entire installation of MySQL servers.

If there were an interface with a relatively small set of primitives—re-directing servers, bringing servers down, add a line to the configuration file, etc.—it would be possible to create pre-canned procedures that can just be executed.

To that end, …

Following our new Milestone-based release model, we've now published MySQL 5.5.0-M2. Please see the "What's New in MySQL 5.5" section of the reference manual for a summary of the most notable changes. The MySQL 5.5.0 Changelog provides a much more detailed list of changes, bug fixes and improvements.

Highlights in this release include:

The InnoDB plugin (currently at version 1.0.5) replaces the built-in InnoDB storage engine. This version includes a number of important performance …

OverviewWhat's this new …

A Hard Look Into Replication For some time now I've been struggling with a slave that invariably stays behind its master. I have been looking at every detail I can possibly think and in the process discovered a number of replication details I wasn't aware until now. I haven't too much information about them in the documentation, but they can affect the way you look at your slaves.
Seconds Behind Master This is the first value that to look at when evaluating replication, most of the monitoring systems I know of rely on it. According to the manual:
When the slave SQL thread is actively running
(processing updates), this field is the number of
seconds that have elapsed since the timestamp of the
most recent event on the master executed by that thread.
In fast networks, most of the time, this is an accurate estimate of …