UPDATE: New room assignments for the MySQL Cluster and Replication Enhancements sessions

With the MySQL Sunday event at Oracle Open World rapidly approaching, and registrations to the event 10x higher than originally forecast, I thought it would be a good time to highlight sessions that are specifically addressing MySQL high availability, including MySQL Cluster .

You can see details and logistics of all of the sessions here

MySQL Cluster
Andrew Morgan and I will be presenting the latest enhancements in the world of …

Gearman provides a generic application framework to farm out work to other machines or processes that are better suited to do the work. It allows you to do work in parallel, to load balance processing, and to call functions between languages.

Gearman provides a generic application framework to farm out work to other machines or processes that are better suited to do the work. It allows you to do work in parallel, to load balance processing, and to call functions between languages.

Welcome to Log Buffer, the weekly roundup of database industry news. We’re only a week or so away from Oracle OpenWorld. Everyone is buzzing with activity, promoting their speaking sessions and making last minute plans. For all of you bloggers who will be attending, don’t miss the annual Bloggers Meetup, announced recently by Alex Gorbachev. “Count yourself in” if you’ll be joining the gang so that accurate attendee numbers can be provided to Jillian’s to ensure everyone is well fed and watered ;)

In recent days, if anything has created massive tremors in the IT industry it is the news of Mark Hurd joining the …

aka “How to use multiple MySQL Servers and Workbench in Snow Leopard without using Terminal… and live happily ever after”

The MySQL Community is a world of command-line aficionados. Many people, including myself, show their love to the simple-but-powerful interface of the mysql command-line client, but not everybody is keen to use a bash shell and give up its GUI, no matter how powerful the software is.

Until recently, GUI tools for MySQL were half baked solutions: in the end, there was always something that you had to do via the command line. Today, you can install, set up and use MySQL on your Mac with Snow Leopard without using Terminal, at all.

My Special Needs

Before digging into the details of the installation, let me describe what I need on my Mac. I use various versions of MySQL and I often need to run 2 or more instances at the same time. I constantly build, install and uninstall versions of …

Gearman provides a generic application framework to farm out work to other machines or processes that are better suited to do the work. It allows you to do work in parallel, to load balance processing, and to call functions between languages.

I worked on the problem recently which showed itself as rather low MySQL load (probably 5% CPU usage and close to zero IO) would spike to have hundreds instances of threads running at the same time, causing intense utilization spike and server very unresponsive for anywhere from half a minute to ten minutes until everything would go back to normal. What was interesting is Same query was taking large portion of slots in PROCESSLIST. I do not just mean query with same fingerprint but literally the same query with same constants.

What we observed was a cache miss storm – situation which can happen with memcache (as in this case) as well as with query cache. If you have the item which is expensive to generate but which has a lot of hits in the cache you can get into situation when many clients at once will have miss in the cache and will attempt to re-create the item pushing server to overload. Now because a lot of requests …

Leif (who works for Spinn3r) published a great post on the mySQL relay-log-space-limit variable and using the page cache efficiently:

When the SQL thread is not able to keep up, logs will accumulate. You can set the location of your relay logs with the relay-log option; in the default configuration (and many production configurations), the relay logs are stored on the same disk as the rest of MySQL’s data. If the total size of the relay logs ever exceeds relay-log-space-limit, the IO thread will pause until the SQL thread has moved on to its next file and deleted its previous one.

Unfortunately, relay-log-space-limit defaults to zero (unlimited). This means that when the SQL thread can’t keep up, the slave’s relay logs will continue to accumulate indefinitely (until its disk fills up). When the total size of …

In MyQuery 3.3, where I just released version 3.3.2 which includes some MySQL Cluster NB specific fixes, there is some support for accessing MySQL Cluster / NDB beyond what is available as ndbinfo table and such things. MyQuery is a Windows based MySQL GUI, if you didn't know that already, and just because you run this tool on Windows (it is only supported on Windows), doesn't mean you cannot monitor a Cluster that runs on, say, Linux. Or Windows, should you so wish.

There are 2 predefined tools that support MySQL Cluster there, one that uses the ability to predefine a SQL statement that runs in a non-modal dialog and is optionally updated and one that uses the feature that allows a DLL, using a sepcfic MyQuery API, to run as a tool, and in this case, this tool is linked up with the NDBAPI to allow monitoring and a certain amount of control overthe Cluster.

Monitoring NDB Cluster memory usage
In MySQL Cluster / …