Just read it !

The only unrealistic part about the scenario is that I fear that most purchasers within a government agency won't be asking these questions, yet.

Technorati Tags: mysql open core open source Share with Shareomatic!

Trackback URL for this post:

http://www.krisbuytaert.be/blog/trackback/879

Now that FOSDEM 2009 in Brussels, Belgium is over, it's about time for a conclusion/summary. I've been to FOSDEM for about five times as both an attendee and speaker, but this year I was much more involved. On Saturday, I gave a lightning talk about "Why you should use Bazaar for maintaining your OSS project". On Sunday, I gave a talk about "MySQL High Availability Solutions" in the main conference track. Both went fairly well and there was good feedback from audience. I've uploaded the slides for both talks to the FOSDEM 2009 page on the MySQL Forge Wiki, video recordings of the sessions should be available on the …

This article accompanies the slides from a presentation on database sharding. Sharding is a technique used for horizontal scaling of databases we are using at Netlog. If you’re interested in high performance, scalability, MySQL, php, caching, partitioning, Sphinx, federation or Netlog, read on …

This presentation was given at the second day of FOSDEM 2009 in Brussels. FOSDEM is an annual conference on open source software with about 5000 hackers. I was invited by Kris Buytaert and Lenz Grimmer to give a talk in the MySQL Dev Room. The talk was based …

I encountered the following text in a man page. Please tell me that I am not alone in thinking that the "typical" solution suggested is WTF worthy...

After calling "commit" or "rollback" many drivers will not let you
fetch from a previously active "SELECT" statement handle that's a child
of the same database handle. A typical way round this is to connect the
the database twice and use one connection for "SELECT" statements.

If the programmer really wants to reuse values from a SELECT statement which occurred within a transaction after the transaction is closed, they should cache those values themselves by populating some variable within their application. IMO, they definitely should not be using multiple connections to the same database from one unit of work unless they are perfectly happy to accept inconsistent data and potentially corrupted inserts and updates.

No wonder …

Based on the official Ubuntu 8.04 package from Sun (thanks to Alfredo Kojima) I prepared a package of MySQL Workbench 5.1.7 for Debian. I am going to upload it to experimental soon, in the meanwhile it is available (amd64 only) from here:

http://people.debian.org/~nobse/mysql-workbench-oss/

Feedback appreciated!

Based on the official Ubuntu 8.04 package from Sun (thanks to Alfredo Kojima) I prepared a package of MySQL Workbench 5.1.7 for Debian. I am going to upload it to experimental soon, in the meanwhile it is available (amd64 only) from here:

http://people.debian.org/~nobse/mysql-workbench/

Feedback appreciated!

HTTP authentication is quite popular for web applications. It is pretty easy to implement and works for a range of http applications; not to mention your browser.

Basic Auth

The two main authentication schemes are 'basic' and 'digest'. Basic is pretty easy to implement and appears to be the most common:

<?php

$username = null;
$password = null;

// mod_php
if (isset($_SERVER['PHP_AUTH_USER'])) {
    $username = $_SERVER['PHP_AUTH_USER'];
    $password = $_SERVER['PHP_AUTH_PW'];
    
// most other servers
} elseif (isset($_SERVER['HTTP_AUTHENTICATION'])) {
    
…

The frustration builds.

I have come to despise MySQL's sql_mode. It is a hack of the most gargantuan proportions.

Basically, the optimizer just ignores the sql_mode whenever it is convenient for it to do so. More importantly, the optimizer silently ignores bad datetime input in various places. The reason for this is because of my statement above: sql_mode is a big ole' hack. Instead of fixing the runtime executor in MySQL to use real ValueObject types — that are immutable and know how to convert (and not convert) between each other, the runtime is a mess of checks for various runtime codes, warning modes, "count_cuted_field" crap and other miscellany that obfuscates the executor pipeline almost beyond recognition.

Slowly, I am attacking the mess, but the executor is so fragile that even tiny changes can wreak havoc on the system, so the going is slow and painful. It's no wonder that the release cycle for the MySQL …

One of InnoDB's features is that memory allocated for internal tables definitions is not limited and may grow indefinitely. You may not notice it if you have an usual application with say 100-1000 tables. But for hosting providers and for user oriented applications ( each user has dedicated database / table) it is disaster. For 100.000+ tables InnoDB is consuming gigabytes of memory, keeping definition in memory all time after table was once opened. Only way to cleanup memory is to drop table or restart mysqld - I can't say this is good solution, so we made patch which allows to restrict memory dedicated for data dictionary.

Patch was made by request of our customer Vertical Response and released under GPL, so you can download it there …

One of the most common patterns I see in my consulting work is identifiers that are generated by MD5() or UUID(). Many times this is done in an application framework or something similar – not software the client has written. From the application programmer’s point of view, it’s just an incredibly handy idiom: generate a unique value and use it, you’re done. Those values tend to appear in session identifiers, but that’s not the only place; I especially notice them in apps that use Java’s Hibernate interfaces, whether session IDs are involved or not.