Sorry for the downtime of this site - until around a week ago I hosted my home page on a trusty Genesi Pegasos II system (powered by a PowerPC G4 Processor clocked at 1GHz, using Debian 4.0 PPC with 512 MB of RAM), serving these pages from my home DSL connection. Unfortunately this system provided no means of redundancy - the hard disk drive died.

Luckily I perform frequent backups, so I moved most parts of the site to a shared hosting space now - the picture gallery is unfortunately too big to fit into the space that I have there. I'll try to move the pictures into my Flickr account instead, but this will take some time.

Note that the primary domain name of this site is now lenzg.net - lenzg.org, (the …

“If it is fast and ugly, they will use it and curse you; if it is slow, they will not use it.”- David Cheriton,  The Art of Computer Systems Performance Analysis (From http://www.kriskrause.com/2009/04/mysql-connector-net-mysqlbulkloader.html)

Weighing cost versus reliability is always a difficult choice in systems administration. (From http://www.linuxhomenetworking.com/wiki/index.php)

I have noticed that people who hate George Bush also hate internet explorer and Windows in general. You people are mentally ill, sorry to say. (From http://sql-info.de/en/mysql/gotchas.html#1_5 )

I finally received confirmation that I’m attending the MySQL Conference 2009, yay! I didn’t really dive deep into all the conference has to offer just because I didn’t want to get too excited and then not be able to go. Now that I do know I’m going, I’m full on with excitement and thought I [...]

Boy am I sick or what, maybe I should see a shrink or something.  What’s the first thing that runs through my head when I wake up on a Sunday morning?  Is it thoughts of family, the days events, happy thoughts or something pleasant non technical?  No.  Its that we need a better benchmark suite for MySQL and the open source database community as a whole.  Right now the staple of our benchmarking diet is sysbench and dbt2.  While both have served their purpose they are a bit long in the tooth and do not do a good job of truly capturing what end users are doing out their.  I mean sysbench uses a single table!   Where’s the join love.  Has anyone outside of a PT expert successfuly gotten dbt2 installed?  probably not because its a pain in the rear.   Plus what the hell does box A got a TPM of 5000 vs box B’s TPM of 6000 mean?  Seriously to a client the only thing it tells is in …

I was soooo tempted to post a 1 word post on this, just posting “Innodb”. It would be very easy, and its the advice that I am going to give in the end anyways. After all we need to get back to the real reason behind these 5 minute DBA topics. These are supposed to be a short tidbit of advice to those who are not going to spend more then 5 minutes making a decision. What’s easier then a single word. Right? But that would be lazy… so. Here goes.

Currently there are only 2 main storage engines that you can consider for your general purpose DB’s. Innodb or MyISAM. While these two storage engines are included with your MySQL installation, there are several storage engines that are in some “pre”-release state that could shake things up in the future.  Because of their relative youth and official release status of these engines, I would probably hold off deploying them unless you are you sure you need them for something.  …

Static probes are being gradually integrated into MySQL. As of MySQL 6.0.9, there are around 55 static probes. To use the static probes, you will have to supply an extra option to the configure script, --enable-dtrace. After the build is over, start mysqld. Now open a terminal, and type $pfexec dtrace -l | grep mysql. You should see something like this:

135 mysql23509            mysqld __1cQdispatch_command6FnTenum_server_command_pnDTHD_pcI_b_ command-done
  136 mysql23509            mysqld __1cQdispatch_command6FnTenum_server_command_pnDTHD_pcI_b_ command-start
  137 mysql23509            mysqld __1cQclose_connection6FpnDTHD_Ib_v_ connection-done
  138 mysql23509            mysqld             handle_one_connection connection-start
  139 mysql23509            mysqld __1cMmysql_delete6FpnDTHD_pnKTABLE_LIST_pnEItem_pnLst_sql_list_LXb_b_ delete-done
  140 mysql23509            mysqld __1cHhandlerNha_delete_row6MpkC_i_ …

Static probes are being gradually integrated into MySQL. As of MySQL 6.0.9, there are around 55 static probes. To use the static probes, you will have to supply an extra option to the configure script, --enable-dtrace. After the build is over, start mysqld. Now open a terminal, and type $pfexec dtrace -l | grep mysql. You should see something like this:

135 mysql23509            mysqld __1cQdispatch_command6FnTenum_server_command_pnDTHD_pcI_b_ command-done
  136 mysql23509            mysqld __1cQdispatch_command6FnTenum_server_command_pnDTHD_pcI_b_ command-start
  137 mysql23509            mysqld __1cQclose_connection6FpnDTHD_Ib_v_ connection-done
  138 mysql23509            mysqld             handle_one_connection connection-start
  139 mysql23509            mysqld __1cMmysql_delete6FpnDTHD_pnKTABLE_LIST_pnEItem_pnLst_sql_list_LXb_b_ delete-done
  140 mysql23509            mysqld __1cHhandlerNha_delete_row6MpkC_i_ …

Image via CrunchBase

Last week I spent some time talking to Michael “Monty“ Widenius (co-founder of MySQL) about his decision to leave Sun.  The bulk of the forward looking aspects of this conversation are going into a post I am preparing for Read Write Web.  This should be out sometime next week. 

While I didn’t want to focus what happened in the past too much in this article I thought I would post some of my own personal assessments I took from my conversation with Monty here.  They are as follows:

• As almost everyone who meets Michael concludes, Michael is a nice guy.  He is transparently open and a pure believer of a common …

We have benchmark parties!  Yes , I spend my weekend glued to the LCD running benchmarks day and night.  While it may seem like the work of a madman or a lonely bunch of geeks without a date who are just trying to pass the time before their WOW quest begins…  its really rather fun.

Check out this:  The RamSan 500 …. I have had access to this bad boy this week to perform all kinds of interesting test.  How fast is it?  50-50 read/write benchmarks I am pulling down 24K iops and I am not taxing the drive ( the benchmark system’s cpu is only a quad core with 2gb of memory )…  I will have a report for you later this week.

What else?  Well my ec2 trials and tribulations continue…  sometimes I feel like I am trying to squeze performance out of an old 386 ( without the co-processor ).

Of course I am …

A few months ago I got a strange email from one of my clients that contained two very simple looking select queries. The only difference between the two queries is that one included the distinct keyword and the other didn’t. The strange part is that the query that used distinct returned zero rows. I spent a few days narrowing down the clients data into a small test case then created a generic test case from that. I also traced the problem to the code that decides which index to use for a group by loose index scan which can be used to resolve queries using distinct.

The example can be found in the bug and in this sql file. My patch was a step in the right direction but not complete enough to solve all the issues. Since this isn’t a crashing but I was tempted to make this blog post into one of those …