Things have been quiet from MySQL over the past month or so, but today's Wall Street Journal has an awesome interview with Sun's Marten Mickos, perhaps the most quotable technology executive on the planet.

I really like how he talks through community (how to provide incentives, what to ...

I'm back from my week of vacation and am ready to pick up where I left off with the interviews I conducted at the Red Hat Summit/FUDCon last month.  After today's, I will have three left: Dennis Gilmore, Max Spevack and Chander Kant of Zmanda.

The Honourable James Zemlin

On the first day of the Summit I was able to grab my buddy Jim Zemlin, the Executive Director of the Linux Foundation for a spirited discussion about the Foundation, Linux and a bunch more. 

My interview with Jim (15:55)  Listen ( …

My previous post on calculating percentiles with MySQL generated some comments and good discussion. In particular, I got some very interesting comments from Vladimir.

Basically, Vladimir was doubtful whether the GROUP_CONCAT() solution would be optimal in comparison to a JOIN. His proposal is to solve it like this:

SELECT   SUM(g1.r) sr
,        g2.length l
,        SUM(g1.r)/(SELECT COUNT(*) FROM film) p
FROM    (SELECT COUNT(*) r, length FROM film GROUP BY length) g1
JOIN    (SELECT COUNT(*) r, length FROM film GROUP BY length) g2
ON       g1.length < g2.length
GROUP BY g2.length
HAVING p > 0.9
ORDER BY p
LIMIT 1

First, this query sets up two identical subqueries in …

Remember the first test of online backup? I tested the new feature, which was performing quite well, compared to mysqldump. OK. Get ready for a surprise.
I tested the native MyISAM driver from the mysql-6.0-backup tree, and I compared the results with the normal backup.

It's finished. After the usual two-week beta period, we can announce the new "final" XAMPP version available for public download.

In this version we updated: Apache (2.2.9), MySQL (5.0.51b), PHP (5.2.6), phpMyAdmin (2.11.7), mod_perl (2.0.4), OpenSSL (0.9.8h), and eAccelerator (0.9.5.3).

Get the downloads and more details on the specific platforms XAMPP project page.

Es ist vollbracht. Nach der üblichen zweiwöchigen Beta-Phase können wir heute die neue "finale" XAMPP-Versionen zum öffentlichen Download anbieten.

Aktualisiert wurden in diesem XAMPP: Apache (2.2.9), MySQL (5.0.51b), PHP (5.2.6), phpMyAdmin (2.11.7), mod_perl (2.0.4), OpenSSL (0.9.8h) und der eAccelerator (0.9.5.3).

Die Downloads und genauere Details zu den neuen Versionen gibt es auf der jeweiligen XAMPP-Projektseite.

I filed these two MySQL bugs today:

Bug#37910 Dropping unrelated index fails if fk on first col
Bug#37925 Select with comma join pretends a column does not exist

They originate with clients, and occur on recent 5.0 versions. No fatal stuff, but annoying. Both are of the fairly awkward variety and I'm curious why they still exist so late in the 5.0 series.

For instance, the second one looks like a parser bug, and I'd have figured someone tripping over this ages ago. It's actually a regression as it worked fine in 4.x, the testcase is directly from an app that was in production on a 4.x server, then upgraded to 5.0. Kaboom on this. Quite unexpected, and very annoying as going through the entire app changing the join syntax is a bit of a pest for the developers.

…

I am a member of the monday morning murder association. I murdered bugs. As said earlier, the modification of PDO_MYSQL to support both the MySQL native driver for PHP (mysqlnd) and the MySQL Client Library (AKA libmysql) is progressing. A good number of known and unknown bugs has been killed. But some new have been found as well - an overview.

(...)
Read the rest of PDO_MYSQLND: Monday morning murders (754 words)

I am a member of the monday morning murder association. I murdered bugs. As said earlier, the modification of PDO_MYSQL to support both the MySQL native driver for PHP (mysqlnd) and the MySQL Client Library (AKA libmysql) is progressing. A good number of known and unknown bugs has been killed. But some new have been found as well - an overview.

(...)
Read the rest of PDO_MYSQLND: Monday morning murders (754 words)

I teach the exact differences and use of the different join types and keywords in my courses (specifically the Optimisation by Design day). A few tidbits:

• Left and right joins are outer joins.
• A,B is an inner join (equivalent to a cross join if you don't have a join condition).

But the point of this post... when looking at apps, I often see LEFT JOINs abused. That is, the query does not actually require a left join. The result might be ok, but that entirely depends on the data contained in the tables; no guarantee.

Apart from understanding joins, I've found that there's a very simple but effective test for whether or not to use a left join.... "if you can't think of a specific reason, you don't" ;-)