If you haven't seen my previous post on the MySQL User Defined Function Repository, take a minute to check it out!!

Today, I did a major structural overhaul of the site, and filled up the roadmap. I have also just added a new library to the project. This library lib_mysqludf_sys contains a number of functions that allows one to interact with the operating system.

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• sys_exec - executes an arbitrary command, and can thus be used to launch an external …

In this version we updated both PHP versions (to 4.4.7 and 5.2.2), MySQL (5.0.41) and phpMyAdmin (to 2.10.1). In the Windows beta we also fixed the security vulnerability published April 28th.

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

I wrote a custom imageless CAPTCHA for my blog a while ago. I didn't write it as a plugin, so I lost it when I upgraded Wordpress a couple weeks ago. Not having this in place to help eliminate comment spam was an eye-opening experience, and vindicated much of what I asserted in my original posts: a naive question-and-answer system is highly effective at stopping spammers, probably as effective as scrambled images. Read on for the details.

My buddy David Pollak, host of a local geekbeer social event, thinks Scala is the next big thing in web programming.  Scala is an object-oriented / functional programming language that compiles down to Java byte code.  It's statically typed but fully supports generics and polymorphism.  And it's published under an open source BSD-like license. 

David's got pretty good street cred; he's built large scale applications in everything from C++, C#, Ruby and pretty much everything else in between.  Over lunch recently he told me in a rather offhand fashion that he used Scala and the related lift framework to write a Twitter clone (called Skittr) in 800 lines that scales to 1 …

Reading this slashdot article today and two CIO magazine articles linked from it.

Such discussions started at right place at right time always attract a lot of flamers and can be fun to read.

What hit me this time is quality of the articles in CIO magazine. If this is what managers suppose to use to make their "informed" decisions about products, not a big surprise huge portion of IT budgets are wasted. It looks like someone who has not got a clue is writing for someone who does not even pretend. I see zero "meat" - mostly using of marketing materials. This applies both to pro-MySQL and against-MySQL articles.

The funniest argument for me was the age of the product. Where does this "older is better" comes from ? Oh yes I know, it comes from the point of view market old timers try to show the value of their …

There are two approaches to do the profiling, i.e. compile-in and sampling.
Compile-in is a method to record the timing of executing each component or function, and the one using the longest time is considered the bottleneck.
Sampling is a method to periodically check what the current active component is, and the one
appearing most frequently is considered the bottleneck.

Compile-in needs to instrument the source code, and may affect the performance due to the overhead of counting and logging. To implement compile-in method, one way is to instrument the source code directly, for instance, using macros to redefine the calls and recompile. We are thinking to use aspect of programming techniques to help the instrumentation so that we can keep the instrumented code and the original code separately.

Sampling involves interrupting the process, and grabbing a stack trace. Sampling may affect the performance …

hackmysql.com is moving to (mt) Media Temple this weekend. Because of Memorial Day, I suspect that site traffic will be really low, so perhaps no one will even notice.

I'm trying to automate some trivial maintenance tasks for my own MySQL server, and trying also to minimize the effort, so ... Here is the recipe:

Take an excellent generalized stored procedure like the one by Konstantin Osipov, see "Dynamic SQL is Stored Procedures" on MySQLForge (example 4).
Tune it a bit so that it takes into account only non system tables (I'm trying to turn it into something similar to Microsoft's sp_MSforeachtable), here is the code:

1. DELIMITER $$
2. DROP PROCEDURE IF EXISTS `test`.`sp_4_each_table` $$
3. CREATE DEFINER=`root`@`localhost` PROCEDURE `sp_4_each_table`(db_name VARCHAR(64), template VARCHAR(21845))
4. BEGIN
5. #
6. DECLARE done INT DEFAULT 0;
7. #
8. DECLARE tname VARCHAR(64);
9. #
10. DECLARE c …

My pal Jeff Barr of Amazon posted on his personal blog about how he was interviewed by Google and continues to get pinged by their recruiters after he already gave them a polite "no thanks". He asks whether their recruiters shouldn't maybe have way of looking up candidates in some sort of database -- you know, maybe like a search engine?

I don't think I've blogged about this yet, but I interviewed at Google from late 2005 through early 2006. The experience was pretty strange. Google kept me on the hook for five full months, having me in repeatedly for meetings with people who had no idea why they were talking to me or what to ask me, putting me in front of middle managers who would theoretically be my superiors but who had far less experience than me, handing me off from one recruiter to another, and never getting back to me when they promised to.

In one of the …

A customer issue has drawn my attention to this this pecularity: if partitioning is done by the value of some function, then partition pruning module will make use of comparisons of the partitioning column(s), but not of comparisons of the value of the partitioning function. Here is an example:

CREATE TABLE t1 ( recdate  DATETIME NOT NULL, ... )
PARTITION BY RANGE( TO_DAYS(recdate) ) (
  PARTITION p0 VALUES LESS THAN ( TO_DAYS('2007-01-01') ),
  PARTITION p1 VALUES LESS THAN ( TO_DAYS('2007-02-01') ),
  ...
);

EXPLAIN PARTITIONS SELECT * FROM t1 WHERE recdate='2007-01-15';
+----+-------------+-------+------------+------+-...
| id | select_type | table | partitions | type |
+----+-------------+-------+------------+------+-...
|  1 | SIMPLE      | t1    | p1         | ALL  |
+----+-------------+-------+------------+------+-...

EXPLAIN PARTITIONS SELECT * FROM t1 WHERE TO_DAYS(recdate)=TO_DAYS('2007-01-15'); …