This Saturday, the 30th, at 4pm, I will be giving a session on MySQL Performance Tuning guidelines at the Ohio LinuxFest, at the Greater Columbus Convention Center. It is directly followed by the PostgreSQL session given by Christopher Browne, so if you're into databases and live in the Ohio area, you should have a bunch of geeks to bond with and share war stories. I'll actually be at the conference for most of the day. Come find me; I'll by wearing my MySQL shirt so I should be easy to find — I'll be challenging PostgreSQL guys to arm-wrestling bouts. Hmmm, forget that. If memory serves me correctly, at Marten's cookout this past April I fared pretty darn poorly in that arena. Best stick to lively debate.

As an aside, I've always …

I do not think you can use the result of a stored procedure in an ad-hoc subquery.

On my social network, LetsGetNuts.com, I have a Friend table. This is the structure:

mysql> describe Friend;
+—————-+—————+——+—–+———+——-+
| Field | Type | Null | Key | Default | Extra |
+—————-+—————+——+—–+———+——-+
| fkUser | int(11) | YES | MUL | NULL | |
| fkFriend | int(11) | YES | MUL | NULL | |
| confirmed | enum(’Y',’N') | YES | MUL | NULL | |
| confirmed_date | date | YES | | NULL | |
+—————-+—————+——+—–+———+——-+
4 rows in set (0.02 sec)

The issue here is that building a list of the friends of a certain user involves using a UNION, and I frequently need to use the concept of IN (FRIENDSLIST). I was …

I and Kostja will be in San Francisco next week. We have plans most of Tuesday but no plans for dinner on Tuesday night.

Anyone up for an impromptu dinner with a couple of MySQL'ers?

Either drop me some email or leave a message in comments. If I get a good response I will announce where we will go for dinner. Any good bars to recommend?

Following on my "the winning mentality" post, here's a nice little image that Paul Kedrosky clued me into. It shows where the Forbes 400 richest Americans live - the billionaires, that is....

Soon enough, I'm expecting to see one dot in Alabama (Digium....), another few in California (SugarCRM, MySQL, etc.), and heck, let's give North Carolina a few more dollars, too.

Open source will crack the billion-dollar barrier, and a lot of people and companies will see the benefit of it. Fortunately, the difference between wealth in open source and wealth in …

Today we have the great pleasure to announce the availability of the simplified Chinese version of our website. Many thanks to ZDYX for all his efforts to make this translation possible.

To the simplified Chinese translation

MySQL has two upcoming European Customer Conferences which will feature customer presentations by the likes of BBC News, Neckermann, Siemens and Tiger Communications.  The events are sponsored by Unisys, which is helping many large clients successfully integrate open source technology into their IT strategy.  The agenda includes a range of business and technical presentations covering case studies, best practices, product roadmap, high availability and performance tuning.

More information is available on the MySQL web site.  Space is limited and last year's events sold out.  So please register early if you want to attend. 

• MySQL: MySQL Hosts European Conferences in October
• London - …

My Regular Exrepssion UDFs for MySQL have been available on MySQL Forge for a while already, now i've taken the time to create a Trac project page for them.

I've implemented the following four functions

* REGEXP_LIKE(text, pattern [, mode])
* REGEXP_SUBSTR(text, pattern)
* REGEXP_INSTR(text, pattern [,position [,occurence [,return_end [,mode]]]])
* REGEXP_REPLACE(text, pattern, replace)

that behave very similar to their Oracle counterparts, using the same regular expression syntax as the MySQL REGEXP operator.

Back in April, I wrote On IPs, hostnames, and MySQL, which described the (sometimes surprising) ways in which MySQL deals with IP addresses, hostnames, and privileges, as well as some basics about the host cache itself. In a footnote to that post, I mentioned a patch I had written against MySQL 4.1 to give some more visibility into the host cache.

Over the past two days, I have worked on porting that patch to MySQL 5.01, 2, and making some fairly large improvements to it. The patch implements a few things:

1. Configurable Size — Without the patch, the size of the cache is fixed at 128 entries, and can only be changed by changing a #define and recompiling. You may now tune the size of the host cache using SET GLOBAL …

The domain registrars are making more money again, this time with .mobi. Naturally, people with a trademark or other (like .com) domain will be wanting to grab their .mobi so noone else can nick off with it. But what's the practical purpose of all these additional toplevel domains?

As far as I can tell, it's just a money making scheme just like .biz was. You may use one or the other to provide advance clarity to your users/customers, but you'll want/need to grab all the domains anyway to keep them safe.
Guh.

In MySQL 5, at the moment you can't write a recursive stored functions. It is forbidden.
Instead you can write a recursive stored procedure. That is not permitted by default but modifying a variable you can achieve such a recursion.
The variable is max_sp_recursion_depth.

SET GLOBAL max_sp_recursion_depth = 0.
A value of zero means: "no recursion" (the default value)

SET GLOBAL max_sp_recursion_depth=255
A value greater then zero means: the maximun number of nested recursion in a procedure. Max value is 255.

Pay attention to the variable named thread_stack, it is the amount of memory allocated for the stack of a thread. Writing a recursive routine the tipical error is to create an infinite recursion An infinite recursion leads very soon to fill up the stack. (the default value of the thread stack is less than 200K)
So, if you have …