We are pleased to announce that MySQL Enterprise Monitor 2.3.6 is now available for download on the My Oracle Support (MOS) web site as our latest GA release. It will also be available via Oracle E-Delivery in approximately 1 week. This is a maintenance release that fixes a number of bugs. You can find more information on the contents of this release in the changelog, which should be visible within 24 hours:

http://dev.mysql.com/doc/mysql-monitor/2.3/en/mem-news-2-3-6.html

You will find binaries for the new release on My Oracle Support:

https://support.oracle.com

Choose the "Patches & Updates" tab, and then use the "Product or Family (Advanced Search)" feature.

And from Oracle E-Delivery (in about 1 week):
…

Following caches are generally available in MySQL. Key Cache This is a shared cache for all B-tree index blocks which are in different MYI files. Internally, this cache is using hashing and reverse linked lists algorithm for quick caching for … Continue reading →

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Windows Server 2008 R2 Failover Clustering

Oracle has announced support for running MySQL on Windows Server Failover Clustering (WSFC); with so many people developing and deploying MySQL on Windows, this offers a great option to add High Availability to MySQL deployments if you don’t want to go as far as deploying MySQL Cluster.

This post will give a brief overview of how to set things up but for all of the gory details a new white paper MySQL with Windows Server 2008 R2 Failover Clustering is available – please give me any feedback. I will also be presenting on this at a …

I will be presenting on MySQL Cluster and MySQL Replication at the Oracle Technical Network MySQL Developer day in London on Tuesday, 18 October 2011 (8:30 AM – 4:00 PM). It’s free but you need to register here while there are still places (attendance has been extremely high at other locations).

The MySQL Developer Day is a one-stop shop for you to learn all the essential MySQL skills. In this free, one-day seminar, we will cover everything you need to know to successfully design, develop, and manage your MySQL databases. You’ll also learn the guidelines and best practices in performance tuning and scalability.

Attend this event and gain the knowledge to: …

We have seen a few instances where upgrades of MySQL 5.1 to 5.5 have resulted in poor performance when using default values. After investigation it would appear that the main culprit appears to be the innodb_thread_concurrency setting.

In MySQL 5.1 the default was 8, while in MySQL 5.5, the default was changed to 0 (unlimited).

So what does innodb_thread_concurrency do and why would it cause performance issues?

The value given to innodb_thread_concurrency sets the number of simultaneous threads the InnoDB engine will create.  If there are more jobs waiting to be processed than there are available thread slots, these jobs will be made to wait until a thread slot becomes free.  So on the face of it, making this unlimited sounds like a good idea - so you won't have any jobs waiting on thread slots.

In an ideal world, unlimited is good.  In the real world, unlimited doesn't exist.  CPUs only have …

The manual says bytes but sometimes it is measured in characters. It seems like group_concat_max_len is in bytes when being passed through a temporary table and in characters otherwise. This works fine when using latin1 but when converting to utf8 mysql must reserve 3 bytes per character when setting types in a temporary table. This is yet another reason to dislike group_concat..

mysql> create table group_concat_bug (str1 varchar(255), str2 varchar(255), str3 varchar(255)) charset=utf8 engine=innodb;
Query OK, 0 rows affected (0.02 sec)

mysql> show create table group_concat_bug;
+——————+———————————————————————————————————————————————————————————–+
| Table | Create Table |
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Installing Lighttpd With PHP5 And MySQL Support On Fedora 15

Lighttpd is a secure, fast, standards-compliant web server designed for speed-critical environments. This tutorial shows how you can install Lighttpd on a Fedora 15 server with PHP5 support (through FastCGI) and MySQL support.

Apache and syslog-ng

While logging to a database back-end has its benefits, the setup as it stands leaves us wanting. Some applications, such as Apache, do not log via syslog-ng by default. The good news is that this can be easily remedied, and there are a couple of different ways of doing this. First, the less good way:

Method #1: Changing the Apache configuration file.

First, we need to setup syslog-ng appropriately by creating a new source for apache, such as the following:

source s_apache {
 unix-stream("/var/log/apache2/apache_log.socket"
 max-connections(512)
 keep-alive(yes));
 };

log { source(s_apache); destination(d_pgsql); };

This recycles the original destination for …

This On Demand webcast gives you a quick preview of the MySQL Quickstart Fundamentals course. During this webcast, you see an overview to new MySQL 5.5 features and benefits and learn how to configure MySQL Server easily.

Special Promotion for MySQL Customers with Oracle Premier Support
Get a 20% discount on Oracle Training. View this datasheet for
more details.

For more information on MySQL Training, see our Learning Paths.

This On Demand webcast gives you a quick preview of the MySQL Quickstart Fundamentals course. During this webcast, you see an overview to new MySQL 5.5 features and benefits and learn how to configure MySQL Server easily.

Special Promotion for MySQL Customers with Oracle Premier Support
Get a 20% discount on Oracle Training. View this datasheet for
more details.

For more information on MySQL Training, see our Learning Paths.