The binary version for MySQL Cluster 6.3.39 has now been made available at http://www.mysql.com/downloads/cluster/

A description of all of the changes (fixes) that have gone into MySQL Cluster 6.3.39 (compared to 6.3.38) can be found in the official MySQL Cluster documentation.

So your not a MySQL DBA, but you have to perform like one. If you have a production environment that’s running now, what are the first things you do when it’s not running or reported as not running?

1. Are the MySQL processes running? (i.e. mysqld and mysqld_safe)
2. Can you connect locally via cli?
3. What’s in the MySQL error log?
4. What are current MySQL threads doing? Locked? long running? how many? idle sources?
5. Can you connect remotely via cli?
6. Verify free diskspace?
7. Verify system physical resources?
8. If this is a slave, is MySQL replication running? Is it up to date?
9. What is the current MySQL load, e.g. reads/writes/throughput/network/disk etc?
10. What is the current InnoDB state and load? (based on if your using InnoDB)

After you do this manually more then once you should be scripting these commands to …

The UK Oracle User Group Conference runs from 29th November through 1st December 2010 – the MySQL content is on Wednesday 1st at the ICC in Birmingham. This is a great chance for MySQL users to find out more on the latest developments and question some of the experts (both from inside and outside Oracle) and for Oracle users who don’t have experience with MySQL to discover what it’s all about.

The day starts with a keynote from Rich Mason (VP responsible for MySQL sales) at 8:45; I’ll be part of a …

Note: It was my first attempt using the MySQL UDF Api back then. The library is still maintained and got some new features. Check out the new MySQL Infusion UDF.

Read the rest »

Dear Kettle fans,

PDI-200 has been out there for a while now.  Jens created the feature request a little over 3 years ago.  I guess the main thing blocking this issue was not as much a technical problem but more of a licensing and dependency one (Oracle JDBC dependency and distribution license).

However, now that we have the User Defined Java Class step we can work around those pesky problems. That is because the Java code in there only gets compiled and executed at runtime so it’s perfectly fine to create any sort of dependency in there you like.

The following transformation reads a set of rows from a stored procedure as described on this web page.

In short, our UDJC step executes the following code:

begin ? := sp_get_stocks(?); …

In the article "Fear of Forking" there was a quote pulled from me about my observations from a yearly call done by the folks at O'Reilly with many of the authors of different open source projects.

"On a related note there was a recent phone call that O’Reilly put together with a number of open source leads. It was amazing to hear how many folks on the call where terrified of how Github has lowered the bar for forking. Their fear being a loss of patches. It was crazy to listen too."

Since I made that comment, there is one new observation I have made. GitHUB has begun to feel like the Sourceforge of the distributed revision control world. It feels like it is littered with half started, never completed, or just never merged trees. If you can easily takes changes from the main tree, the incentive to have …

In the article "Fear of Forking" there was a quote pulled from me about my observations from a yearly call done by the folks at O'Reilly with many of the authors of different open source projects.

"On a related note there was a recent phone call that O’Reilly put together with a number of open source leads. It was amazing to hear how many folks on the call where terrified of how Github has lowered the bar for forking. Their fear being a loss of patches. It was crazy to listen too."

Since I made that comment, there is one new observation I have made. GitHUB has begun to feel like the Sourceforge of the distributed revision control world. It feels like it is littered with half started, never completed, or just never merged trees. If you can easily takes changes from the main tree, the incentive to have …

Ewen and I have just published Percona’s latest white paper, Forecasting MySQL Scalability with the Universal Scalability Law. This is essentially a streamlined walk-through of Dr. Neil J. Gunther’s book Guerrilla Capacity Planning, with examples to show how you can apply it to MySQL servers.

One thing alluded to in the paper is extracting the necessary metrics from network traffic. I had this idea after studying the data in Linux’s /proc/diskstats file. It turns out that two simple metrics can provide amazingly rich insight into system performance and scalability, in combination with Little’s Law and queueing theory. These are the busy time and the total time that requests were resident in the system. There are different terms for the latter, but in MySQL we’d call it query response time. After studying these for a few months, I’m so …

Last night a customer had an emergency in selected machines on a large cluster of quite uniform database servers. Some of the servers were slowing down in a very puzzling way over a short time span (a couple of hours). Queries were taking multiple seconds to execute instead of being practically instantaneous. But nothing seemed to have changed. No increase in traffic, no code changes, nothing. Some of the servers got sick and then well again; others that seemed to be identical were still sick; others hadn’t shown any symptoms yet. The servers were in master-master pairs, and the reads were being served entirely from the passive machine in the pair. The servers that were having trouble were the active ones, those accepting writes.

The customer had graphs of system metrics (++customer), and the symptoms we observed were that Open_tables went sharply up, the buffer pool got more dirty pages, InnoDB started creating more pages, and the …

Until now, when you observed a performance degradation with a growing number of concurrent user sessions in InnoDB the most simple way to avoid such a degradation was to set innodb_thread_concurrency to something different from zero (zero is a default now in 5.5) - and since 5.5.4 the most optimal value was around of 32 (before it was 16 )... But all latest performance improvements in 5.5 are so good that it become less and less true now, and during my last tests I've even observed a worse performance when a different from zero "innodb_thread_concurrency" setting was used.. - seems to me now the overhead of the thread concurrency management code in some cases become more important than an overhead of still existing lock contentions ;-)

Let's see more in details now..

First …