Using ROLLBACK with MyISAM is useless. A ROLLBACK command is used to undo any DML that occurs during a transaction (i.e. START TRANSACTION and COMMIT). The MySQL default storage engine MyISAM does not support transactions.

It is easy with the SHOW GLOBAL STATUS command to see if your application code uses ROLLBACK. By performing two samples you can look at the delta over time. The statpack utility is one product that provides a human friendly display of this delta. As seen below, the use of ROLLBACK in combination with the read/write ratio and the my.cnf –skip-innodb indicate unnecessary database work.

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                    Variable    Delta/Percentage         Per Second              Total …

A colleague pointed me at More fun with the MySQL Audit Plugin API which looks very interesting.  Analysis of the queries going on inside a msyqld has been something that has been wanted for some time.  Until now it’s only been possible with external addons such as MySQL Enterprise Monitor which do a good job. However, really the place for this functionality is inside the db server itself. If 5.5 m3 provides the hooks to do this that’s great news and while Anders’ first implementation may be simple, this can surely be extended in many ways.

The things I would like to see added to this plugin are the following many of which are safeguards to ensure you can use functionality on a system like this in production without …

As I already wrote, I will be speaking at the MySQL Conference & Expo in Santa Clara in two weeks and I am excited to be there again. This year's conference is going to be interesting for a number of reasons, but most importantly I think that the schedule looks great! This is going to be a "drinking from the firehose of MySQL knowledge" event. Afterwards, I'll be on parental leave in May and June, so I likely will miss a lot of great conferences – these months are usually quite packed, as our Open Source Events Calendar can confirm. I just received a notice that my talk submission …

Berkeley DB (BDB) is undoubtedly the workhorse among the opensource embedded database engines. It started as a university project in the mid-eighties and was further developed by Sleepycat Software, until it got acquired by Oracle in February 2006.

I had the impression that BDB had lost a lot of its popularity among opensource developers to SQLite in recent times, which has evolved into becoming the default choice for developers looking for an embedded data store. I'd assume primarily because the code is not released under any particular license, but put in the public domain …

Brian wrote recently Where did all of the MySQL Developers Go?, while over in Drizzle land they have been accepted for the Google Summer of code along with many other open source projects. MySQL from my observation a noticeable absentee.

Historically, the lack of opportunity to enable community contributions and see them implemented in say under 5 years, has really hurt MySQL in recent times. There is plenty of history here so that’s not worth repeating. The current landscape of patches, forks and custom MySQL binaries for storage engine provider has provided a boom of innovation that sadly is now lost from the core MySQL product.

In Drizzle, community contribution is actively sought and a good portion of committed code is not from the core Drizzle …

Since the time that I’ve been using MySQL I have filed quite a few bug reports. Some of these have been fixed and many of the bug reports are actually new feature requests. While working with MySQL Enterprise Monitor I’ve probably filed more feature requests than bug reports.

That’s fine of course and my opinion of what is needed in MySQL or Merlin is one thing,  yours or the MySQL developers is something else. We all have our own needs and find things missing which would solve our specific problems.

If I have ten feature requests open and only one could be added to the software I’d also like to be able to say: this feature is the most important one for me.

However, it seems to me that there is no easy way in the mysql bug tracker at the moment to group together different types of new feature requests into groups of related features and then see the different types of …

1. Common MySQL Queries -- a useful reference.
2. MySociety's Next 12 Months -- two new projects, FixMyTransport and "Project Fosbury". The latter is a more general tool to help people organise their own campaigns for change.
3. riak -- scalable key-value store with JSON interface. (via joshua on Delicious)
4. Notes from NoSQL Live Boston -- full of juicy nuggets of info from the NoSQL conference.

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A key differentiator in Drizzle from it’s original MySQL roots is user based authentication. Gone is the host/user and schema/table/column model that was stored in the MyISAM based mysql.user table.

Authentication is now completely pluggable, leveraging existing systems such as PAM, LDAP via PAM and Http authentication.

In this post I’ll talk about HTTP authentication which requires an external http server to implement successfully. You can look at Part 1 for …

A key differentiator in Drizzle from it’s original MySQL roots is user based authentication. Gone is the host/user and schema/table/column model that was stored in the MyISAM based mysql.user table.

Authentication is now completely pluggable, leveraging existing systems such as PAM, LDAP via PAM and Http authentication.

In this post I’ll talk about PAM authentication which is effectively your current Linux based user security.

This information is based on the current …

This week with a client I saw ext4 used for the first time on a production MySQL system which was running Ubuntu 9.10 (Karmic Koala). I observe today while installing 9.10 Server locally that ext4 is the default option. The ext4 filesystem is described as better performance, reliability and features while there is also information about improvements in journaling.

At OSCON 2009 I attended a presentation on Linux Filesystem Performance for Databases by Selena Deckelmann in which ext4 was included. While providing some improvements in sequential reading and writing, there were issue with random I/O which is the key for RDBMS products.

Is the RAID configuration (e.g. RAID 5, RAID 10), strip size, buffer caches, LVM …