It's time to turn our attention to the sixth edition of Log Buffer, a Carnival of the Vanities for the DBA community.

This week, like every week, DBAs all around the world have been hard at work writing about their experiences, many of them providing detailed instructions on new and interesting ways to use and manage a database.

For folks wondering if it's worth all the work, Eddie Awad's Blog now has the latest results from his Unofficial Oracle Developer/DBA Salary Survey. The results are interesting, and hopefully encouraging. While the data is why we all rush there to see where we stand, there's also a good summary of the process Eddie went through to run and process the …

Setting up MySQL replication is fairly easy. Just tell the slaves which master they need to connect to and make sure the master is writing binlogs. Ok, it is a little more complicated, but in the end it's pretty straight-forward.

If however you have large number of slaves and a rather busy master machine, the network load can become significant. This is because all statements that are written to the binlog are transferred to all the slaves. They put them into their relay logs and asynchronously process them. Each slave may decide which statements need to be executed and which can be discarded. This is especially useful in setups where there are tables modified on the slaves that should not be replicated.

Use case

In a production scenario we have up to 35 slaves configured against a single master. The master does "full" binlogs, i. e. no exceptions are made. This is done on purpose, because the binlogs are backed up for …

This is more a reminder for myself than a regular post. Because I have been fiddling around with the xorg.conf to get my Linux desktop right with dual head and the right resolution on each screen, I post my configuration here. If anybody finds it useful, they are welcome to copy it.

I am currently using Ubuntu 6.06 (Dapper Drake) which comes with X.Org 7.0. My machine has a GeForce 5600XT based graphics board by LeadTek. It has a DVI-I and a VGA port. I installed the closed-source nvidia driver to get hardware acceleration and extended features the X.Org nv driver does not provide. Moreover I could not get dual head right with the X.Org driver.

The following configuration sets up two screens, one for the left display (analogue TFT, 1280x1024) and one for the right (CRT, 1024x768).

# /etc/X11/xorg.conf (xorg X Window System server configuration file)
#
# This file was generated by …

Now this is the late "Part 1 of 2" (Part 2 was published first). Took me longer than expected, but I finally got it done.

In the beginning there was Windows...

I have been working with all versions of Windows starting with 3.0 on a 386SX16. Over the years I have gained extensive knowledge about many aspects of the inner workings, the weaknesses and strengths. Up to now I have been using Windows XP as my "main" operating system. It certainly has its flaws, but all told it is a fine piece of software.

I also believe to have a somewhat profound insight into Linux. I started with Debian Potato and have since used both newer Debian versions (Woody and Sarge) as well as several flavors of Red Hat (beginning with RH9, up to FC5) and some SuSE, too. Right now I am using Ubuntu Dapper Drake 6.06 to write this. However the majority of the …

Please note that I am in no way affiliated with MySQL (AB). I am just a user of their products. Everything you read here, especially my explanations and conclusions are to the best of my knowledge, but there is a chance that they are awfully wrong!

I recently had to investigate the cause for a very long running delete operation in one of our applications. Apparently the time was spent in a single MySQL statement. While looking into the matter I exchanged numerous mails with the MySQL customer support, until I finally came up with a (much) improved version of the query. Along the way I learned some valuable information about MySQL's (or better InnoDB's) transaction levels.

Problem

The general problem looks quite simple:

• Three tables, let's just call them A (500.000 rows), B (4.000 rows) and C (180.000 rows)

• B contains detail information for …

In my previous post about enhancing the graphs the MySQL Administrator displays I added a remark that there seems to be a difference between MySQL 4.1 and 5.0.

As it seems this has already been reported as MySQL Bug #10210 and fixed, however only for 5.1. Summarizing the bug report is easy: They implemented Heisenberg (or better: the observer effect). You cannot query the counters for e. g. the number of temporary tables created without modifiying it as you go. In 4.1 all the SHOW STATUS... commands (see the manual page) could be executed without modifying the values displayed, because they …

Update: MySQL 4 and 5 behave differently.
In MySQL5 there is a steady activity on some handlers, probably caused by the status queries themselves. This does not happen in 4.1. I have issued a support call with MySQL and will see what to do about it.

Update 2: See the follow-up post for more information on how to work around this.

MySQL Administrator is one of the graphical tools MySQL provide to manage their database servers. Apart from other things like server daemon control and a log file viewer this tool includes visual controls to display the load of the database server.

Even though the out-of-the-box configuration already contains some useful diagrams, I added some …

As many of you know already, I’ve decided to leave Yahoo!. Today was my last day. I’ve had a great time at Yahoo! and worked with a bunch of brilliant people. I will miss you all!

Where am I headed? That’s actually a complicated question. I’ll be working part time at Pivot3, a mature startup that’s doing great things in the storage industry. Contact me if you’re interesting in cutting storage costs, getting some amazing management tools, and some awesome performance. I would love to tell you more! MySQL will absolutely rock on this platform.

Yes, I said part time. I have a startup of my own, Proven Scaling, providing advanced MySQL …

When setting up MySQL replication there are some things to remember. Although the setup is quite easy if you thoroughly read the documentation on MySQL's developer site you might still hit some issues.

We have quite a large scale replication setup (MySQL 4.1.12) with several hundred slaves. Today we saw a very strange situation: All of the slaves stopped replicating and claimed that a statement had been partially executed on the master side. The exact message was

Query partially completed on the master (error on master: 1053) and was aborted. There is a chance that your master is inconsistent at this point. If you are sure that your master is ok, run this query manually on the slave and then restart the slave with SET GLOBAL SQL_SLAVE_SKIP_COUNTER=1; START SLAVE;

The error code 1053 which means as much as "server shutdown".

We checked the master and could not …

Back in April MySQL had its yearly user's conference. Each year there are more users and more people to talk to, which means I get fewer chances to listen to any of the talks being presented. I did though take time out to listen to the talk on Second Life. I've been playing with BBS'es, Talkers, and other assorted digital online communities ever since I got my first modem. What fascinated me about Second Life was the prospect of it taking a shot at being the first "metaverse". I am a big fan of "Snow Crash" and would love to see that sort of environment spring to life. I work daily with friends and colleagues using IM and IRC, and any depth that can be added to those conversations is great as far as I am concerned.

I have also been fascinated with learning about how they are scaling with MySQL. Their design is fairly classic with replication, but what is interesting is to look and see how this is applied to a virtual …