Yesterday, Geir Høydalsvik and I had the pleasure of hosting a MySQL mini-seminar in Trondheim, Norway.

The topic of the day was a presentation by yours truly on how the MySQL optimizer works. Geir briefly explained how the MySQL teams are organized in Oracle, and that our focus is on delivering high quality on time.

We had lots of interesting questions and discussions (and pizza) afterwards. Of particular interest was:

• How the MySQL code base can be modularized to make it maintainable and testable. The takeaway was that MySQL has invested a lot on refactoring the last couple of years to improve in this area and will continue to do so in both the near and far future.
• How testing is done in MySQL. The answer was that the QA teams have been significantly ramped up since Sun acquired MySQL. In addition to much more resources to the QA teams, developers are now expected to write unit tests …

There are several approaches to count the occurrences of a substring inside a larger string in MySQL. Some people use replace() and length() (I would use char_length() instead) to do it. Others use stored functions. Recently I had to count the occurrences of a certain key across many rows of JSON. Instead of writing my own query using one of the approaches mentioned above I decided to use common_schema.

In the past I've discussed JSON parsing in MySQL using common_schema. In this case …

I posted the slides to my talk on SlideShare.  This talk includes high level information about Shard-Query, why it is needed, and the kind of schema it works well with.
http://www.slideshare.net/MySQLGeek/introduction-to-shard-query-m

You can also find a more technical information about Shard-Query and the how it works here:

Divide and conquer in the cloud from Justin Swanhart

As mentioned here and after talking to a few people we have created a meetup page, http://www.meetup.com/Madrid-MySQL-users-group/ and proposed the first meeting on Thursday, 4th July. If you are interested and in the area come along and say hello. It should be interesting to see a few others who work in the field.  If you can let us know you are coming so we have an idea of how much interest there is.

Join 6100 others and follow Sean Hull on twitter @hullsean. Lots and lots of web applications need to page through information. From customer records, to the albums in your itunes collection. So as web developers and architects, it’s important that we do all this efficiently. Start by looking at how you’re fetching information from your [...]

Timing is everything. I wrote about how MySQL man pages were silently relicensed away from the GPL. It was picked up by a lot of sites: Hacker News, Slashdot, LWN, and probably more. That led to a bug report in Debian (#712730) to complain that MySQL is no longer compliant with the Debian Free Software Guidelines (DFSG). That prompted Norvald Ryeng who’s active in Debian (thanks Oracle!) to file MySQL bug …

Tokutek is known for its full-featured fast-indexing technology. MongoDB is known for its great document-based data model and ease of use. TokuMX, version 1.0, combines the best of both worlds.

• So what, exactly, is TokuMX? The simplest (but incomplete) answer is that TokuMX is MongoDB with all its storage code replaced by Tokutek’s Fractal Tree indexes.
• How do Fractal Tree indexes improve MongoDB? The direct benefits include high-performance indexing, strong compression, and performance stability – in other words, the performance stays high, even when data is larger than RAM.
• Are there any features in TokuMX that MongoDB doesn’t have? Yes. We have added support for transactions to TokuMX, so that TokuMX is ACID compliant and has MVCC. We have also added support for clustering indexes, which dramatically accelerate many types of queries.
• …

Wow – blips like this are still causing firestorms? I remember the Debian/manpage storm: http://mcslp.wordpress.com/2008/02/01/mysql-documentation-and-debianubuntu/