First, a bit of background information… MySQL has a variable called tmp_table_size which is used whenever a temporary table is needed for many types of operations, but it’s mainly used for ORDER BY and GROUP BY. The tmp_table_size variable (in correlation with the max_heap_table_size variable) decide at what point to convert an in-memory (that is, HEAP storage engine) temporary table to an on-disk (that is, MyISAM) one.

So, if the result of your query will end up greater than the lesser of tmp_table_size or max_heap_table_size, once it reaches that point, it will be automatically converted to a MyISAM table, on-disk (in tmpdir, incidentally).

Here’s a scenario: You have a SELECT query, nothing particularly special. It isn’t any more complex than another query on the same tables, but it performs a bit worse. You put some load on it, and it performs miserably, even putting the server in pain in the process. You check what’s …

A friend of mine recently asked me to show him how to enable cascading deletes between tables in MySQL. Cascading updates and deletes can be turned on between tables related with foreign keys in many RDBMSs. Though they can be convenient for some purposes, they can have unexpected side effects, and can be very confusing and dangerous at times. In this article I’ll discuss some of the ways cascades can do invisible things, and show you one place they can be very handy too.

MySQL Bugs: #18866: ndbd segfaults when starting 2 times

Jonas is just incredible, not even 3 minutes after I report a bug he replies to it. It takes me 4 minutes to realise it's actually duplicate, and by the time I want to comment on that myselve I see that he already made the same comment.

No way you can ever get that from a proprietary software company !

A quick workaround for the tablespace bug I reported earlier to MySQL.

An extent can't be reused to another table until a LCP has been performed. You can force a LCP by using 'ndb_mgm -e "all dump 7099"'

At least now you can cotinue adding stuff to your database while not having to add extra tablespaces altough you deleted the data ... to be continued :)

No, this isn't about our multi-year extension of the InnoDB agreement with Oracle...  Instead, Apple has said that they will enable intel Mac users to run Windows.  Ok, they are doing it in an unsupported fashion with a bootloader called "Boot Camp" and customers need to install their own copy of Windows XP.  But still, it's a significant change of mind from Apple.  Well done guys!  Maybe Dvorak was right all along.

What's next?  Will Microsoft give a keynote at LinuxWorld?  Actually that happened this morning also, with Bill Hilf, General Manager of Platform Strategy.  …

The Spread Toolkit is one of my favorite Open Source projects. Spread lets you send multicast group messages between applications. It provides reliable, ordered, asynchronous message delivery, and it's efficient, works on large wide-area networks, and can survive and recover from network failures.

What kind of things could you do if a MySQL server could send and receive messages using Spread? I started a new project, the MySQL Message API, to find out. For a few ideas to get started with: if you want to notify a bunch of application servers whenever a particular table changes, you can write a simple trigger to send them all a message. Or if you have lots of different specialized database servers powering your 30-million-user social networking site, you might want to send messages from one server process them (with stored procedure code) on another.

The Message API is a set of MySQL …

For all of the innovation that occurs in today's technology marketplace, the most commonly used business applications-those associated with Microsoft Office -- remain stale and hackneyed. While we wait for Microsoft to come out with a new version of Office that overshoots user need while ensuring that consumers, businesses and government remain locked into Microsoft specific standards, I put forth the notion that an open source business productivity suite has the rare opportunity to dislodge Microsoft's stronghold on the desktop - it just needs a little help from the community.

The Ultimate Battleground?
We are on the cusp of a unique time in the Microsoft product lifecycle. Both Office 12 and Windows Vista loom on the horizon and IT shops and end-users around the world will have to decide just how much extra they are willing to pay (again) for applications like Powerpoint and Access, and how much they plan to use InfoPath and …

I'm using DBDesigner 4 quite a lot. I think the successor, MySQL Workbench, is very promising, but it does not meet my requirements (yet).

Having DBDesigner Generate SQL
Those that've worked with DBDesigner have probably noticed the particular strategy it uses to generate SQL code from the model. First of all, the user needs to specify what kind of SQL script is to be generated: a DROP, CREATE or optimization script. Then, DBDesigner does it's thing. In case of a DROP or CREATE script, exactly one statement is generated for each table in the diagram (or in the current selection if you choose to).

In case of the CREATE script, each CREATE TABLE statement contains not only the column …

I looked through the results of the 2006 SourceForge.net Community Choice Awards and was very happy to see that phpMyAdmin came out first in the Database and SysAdmin categories. Congratulations to Marc Delisle and the rest of the phpMyAdmin team!

phpMyAdmin will actually be showcasing their project in the DotOrg Pavilion at our MySQL Users Conference, taking place April 24-27 in Santa Clara, California. One more reason to not miss this event!

Today I was at the OSS Forum day in Hobart, really interesting. I was honoured to do the opening keynote, which I think was very well received. I met and talked with many good people. There's a lot going on here. Excellent.

This evening talked at the local Linux users group (TasLUG) about MySQL 5.1, which drew a fairly big crowd and we covered some very good and in-depth questions! Oh and the pub had good food, too...

From there, I went on a little two-hour roadtrip North and am now writing this from a hotel room in Launceston. The hotel is charging me an exorbitant amount of money to pick up some email on my laptop, about $0.50 cents per minute and it has just notified me that I actually reached some limit so it's now charging $0.20 per additional MB. Just great.

But, Launceston. I'll be speaking at the local TAFE (colleges …