The MySQL Master-Master replication (often in active-passive mode) is popular pattern used by many companies using MySQL for scale out. Most of the companies would have some internal scripts to handle things as automatic fallback and slave cloning but no Open Source solution was made available.

Few months ago we were asked to implement such solution for one of the customers and they kindly agreed to let us release things under GPL2 License, and we gave them reduced rate for being Open Source friendly.

So what does this tool do and how it works ?

Currently it is implemented based on Linux IP management tools and LVM for snapshot creation but we hope support for other operation systems added in the future.

It can manage master-master pair as well as other configurations such as master-master and bunch of slaves.

Typically you would define "roles" for example READER and WRITER roles for most simply case and …

Jonathan Schwartz said something very interesting on his blog today. (I wish he blogged more, and with fewer happy Sun employee faces in his blogs, but this one was good.) He was talking about Sun's licensing of its Neptune ASIC to Marvell, and made this comment:

For years we were called proprietary - a moniker that did more damage to Sun than any market downturn. And frankly, we've spent years recovering. But at this point, my hope is we've completely turned that slur on its head, that we've come to define open - more open than any other vendor, more open than open itself. From silicon to systems, software to storage and services.I get a lot of grief for being an open source bigot. Few that make that claim seem to understand that I spent my years in the "hybrid" wilderness. It didn't work. That's why I've increasingly opted for a pureplay open source view. …

I'm in the middle of finalizing Alfresco's (for the Americas) sales compensation plan. It has been one of the most difficult things I've ever done. You'd think it was just a matter of setting commission percentages and accelerators, but it's harder than that. It's very difficult to fine-tune incentives so that nomads work for the group.

One of the aspects of creating the plan was what to do with renewals. Some of Alfresco's peers comp renewals - others don't. Some give full commission and booking credit in the first year, and then 50% commission credit (and no booking credit) thereafter.

I've opted to fully comp and credit renewals. Why? Because it aligns interests between the salesperson and the customer. (One large open source company has apparently adopted this model recently, having started with a "no reward for renewals model," so companies of any size can adapt to it.) …

Not sure if you saw this from yesterday's Champions League match, but the Roma riot squad went wild on the visiting Manchester United fans. (You can see it in action here.) Apparently (and I'm sure this is true), the ManU fans weren't pleased when they went down 1-0 before half, and started throwing objects at the home Roma supporters. (Note to ManU fans: 4,000 against 50,000...you don't want those odds.)

Manchester United is denouncing the "indiscriminate beatings." Roma, no doubt, believes they were simply containing the British hooligans. For those beaten, it really doesn't matter. They're bleeding.

Beauty is in the eye of the beholder. Thuggery is in the eye of the club-holder.

I'm constantly surprised by how many in the proprietary space believe that they're being beat up by open source. Billion-dollar companies whining about open source …

Many of you who use MySQL replication have requested that we do more to assist you in monitoring and troubleshooting issues with various replicaton topologies. Right now, we’re in the process of designing replication monitoring enhancements for our current Monitoring and Advisory Service so I thought I’d request your input on what you’d like to see.

The most common questions I hear that come up with respect to replication monitoring are these:

- Are there any global replication issues in my monitored replication topologies?
- Do I have any down master servers?
- Do I have any down slave servers?
- Are my SQL and I/O slave threads running on my slaves?
- Is the replication latency between any master and slave too high?
- What are the top ?N? worst performing (highest latency) slaves?
- Have any slaves experienced a replication-specific error?
- What are the last ?N? errors in a …

When I wrote my first article on algorithms to compare and synchronize data between MySQL tables, Webyog's Rohit Nadhani left a comment on the article mentioning the SQLyog Job Agent, which has a similar function. Although I have been developing MySQL Table Sync essentially in isolation, I have been meaning to give SQLyog Job Agent a try. I recently did so, and then followed that up with an email conversation with Rohit. This article is about my experience using the SQLyog Job Agent from the command line, some thoughts on the algorithm as best I can deduce it, and benchmark results against MySQL Table Sync.

Dear Developers,

we are proud to announce the beta version of the MySQL native driver for PHP: mysqlnd 5.0.1-beta. The software is available for download on http://dev.mysql.com/downloads/connector/php-mysqlnd.

The MySQL native driver for PHP is an additional, alternative way to connect from PHP 5 and PHP 6 to the MySQL Server 4.1 or newer. It is a replacement for libmysql, the MySQL Client Library. From now on you can use ext/mysqli either together with libmysql as you did in the past or with mysqlnd. The MySQL native driver for PHP can connect to MySQL Servers 4.1 or newer.

As stated before, we have no plans to remove libmysql support …

Dear Developers,

we are proud to announce the beta version of the MySQL native driver for PHP: mysqlnd 5.0.1-beta. The software is available for download on http://dev.mysql.com/downloads/connector/php-mysqlnd.

The MySQL native driver for PHP is an additional, alternative way to connect from PHP 5 and PHP 6 to the MySQL Server 4.1 or newer. It is a replacement for libmysql, the MySQL Client Library. From now on you can use ext/mysqli either together with libmysql as you did in the past or with mysqlnd. The MySQL native driver for PHP can connect to MySQL Servers 4.1 or newer.

As stated before, we have no plans to remove libmysql support …

In MySQL 5.0, with the introduction of information_schema, the SHOW commands were changed to really be wrappers around SELECTs against information_schema. This means that when you issue e.g., a SHOW VARIABLES command, Created_tmp_tables is incremented once, and Handler_write and Handler_read_rnd_next are incremented about once per row in the result. Keep this in mind in your monitoring systems; these numbers could be wildly inaccurate if some part of your application is doing many SHOW commands.

This came to my attention because Connector/J’s ReplicationDriver runs SHOW VARIABLES LIKE ‘tx_isolation’ whenever you switch between setReadOnly(true) and setReadOnly(false), so in large, complex Java applications don’t be surprised if you see a high number1 of Created_tmp_tables. How can this be solved? Use SELECT instead of SHOW. If you need to access one variable, instead of doing:

SHOW VARIABLES LIKE 'tx_isolation'

…

I just finished working with our great dev team (thanks Chad and Giuseppe!) on working out a few minor kinks with the new SQL Profiler that was introduced in the 5.0.37 version of the MySQL Community Server. Overall, the SQL Profiler is a great new diagnostic aid that helps you understand exactly where your queries are spending their time during processing and execution. It’s also a great example of the MySQL community in action as the Profiler was originally developed outside of MySQL by Jeremy Cole of Proven Scaling.

I just finished a new article on the Profiler that demonstrates how to use it for troubleshooting problem SQL queries. Check it out when you can and let me know what enhancements you’d like to see to the Profiler that would make it even better.