The latest from the MySQL community

This has me thinking:

When Amazon S3 receives a PUT request with the Content-MD5 header, Amazon S3 computes the MD5 of the object received and returns a 400 error if it doesn’t match the MD5 sent in the header. Looking at our service logs from the period between 6/20 11:54pm PDT and 6/22 5:12am PDT, we do see a modest increase in the number of 400 errors. This may indicate that there were elevated network transmission errors somewhere between the customer and Amazon S3. We are continuing to investigate and will post an update when we have further information.

The MySQL protocol doesn’t seem to have a checksum or hashcode:

If a frame were corrupted in a way that didn’t break the SQL, …

I was asked today about the ANSI_QUOTES SQL mode.

According to http://dev.mysql.com/doc/refman/5.0/en/server-sql-mode.html, ANSI_QUOTES mode changes the functionality of double quotes (”) to be like the backtick (`). Normally the functionality of double quotes is more like that of single quotes (’).

You might use this when you have a table with spaces or other special characters you would like to escape, without having to use the backtick key. This is also ANSI standard SQL behavior (one of the more annoying things about Oracle is that I keep forgetting I can’t use “, only ‘).

Here is an example in the MySQL default mode — allowing ” to be more like ‘ :

mysql> use test;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database …

Testing MySQL sequential IO performance with different IO schedulers – Part 1

I stumbled upon an interesting article discussing the different Linux I/O schedulers that are available in the 2.6 kernel, and also discussing some of the deficiencies of the 2.4 “Linus elevator” I/O scheduler.

The default scheduler as of Kernel 2.6.18 is the “Completely fair queuing” scheduler, or CFQ. The previous default was the anticipatory scheduler between 2.6.0 and 2.6.17. Also available is a buffed-up version of the 2.4 scheduler called the deadline scheduler, and a “noop” scheduler. This article has a great discussion on what these schedulers mean for databases at a higher level.

Although old, …

Installing MySQL Proxy On CentOS 5 (FINAL) x86_64

This tutorial explains how you can install MySQL Proxy on a CentOS 5 (x86_64) system. MySQL Proxy is a simple program that sits between your client and MySQL server(s) that can monitor, analyze or transform their communication. Its flexibility allows for unlimited uses; common ones include: load balancing; failover; query analysis; query filtering and modification; and many more.

Installing MySQL Proxy On CentOS 5 (FINAL) x86_64

This tutorial explains how you can install MySQL Proxy on a CentOS 5 (x86_64) system. MySQL Proxy is a simple program that sits between your client and MySQL server(s) that can monitor, analyze or transform their communication. Its flexibility allows for unlimited uses; common ones include: load balancing; failover; query analysis; query filtering and modification; and many more.

I’ve joined Pythian and thought I would present myself and give my initial opinions on Pythian as employer.

First off, I should mention that although I’ve been working with MySQL for a long time, I’ve never actively gotten into the blogging in the past, but all of that is about to change. I’ll be posting about research and problems I encounter, much like everyone else, and I hope I’ll be able to shed some light on issues that other people run into.

I just transferred to Pythian Europe from my old employer in the US, because I was tired of the American life and wanted to move back to Europe for personal reasons, and during that process I came in contact with Pythian and realized that this company is everything I wanted in an employer, plus I get to work in the services sector, which is something I really enjoy. Either way, I decided to come on board, and now I’m on my way to the corporate head office in Ottawa for initial …

I was writing a utility in Python (using boto) to test/play with Amazon’s SQS service. As boto isn’t particularly well documented where SQS specifically is concerned, I also plan to post some examples (either here or on Linuxlaboratory.org, or both). When I had some trouble getting a message that was sent to a queue, I went to the Amazon documentation, and found this little gem in the Amazon Web Services FAQ

I am sure that my queue has messages, but a call to ReceiveMessage returned none. What could be the problem?

Due to the distributed nature of the queue, a weighted random set of machines is sampled on a ReceiveMessage call. That means only the messages on the sampled machines are returned. If the number of messages in the queue is small (less than 1000), it is …

The second half of last week I attended the Red Hat Summit and FUDCon which Sun and MySQL were silver sponsors of.  The events were co-located at the Hynes convention center in Boston. 

Although both events featured an impressive list of topics and tracks, other than the keynotes I spent the majority of my time meeting and talking to people.   One of my goals was to figure out how Sun can better work with Fedora to get more of our software into their distro. 

A few key Fedorans: Max Spevak, Dennis Gilmore, Tom "Spot" Callaway, Jeremy Katz, Paul Frields, Jesse Keating. 

President and CEO Jim Whitehurst chats with Fedora board member, Karsten Wade, …

The second half of last week I attended the Red Hat Summit and FUDCon which Sun and MySQL were silver sponsors of.  The events were co-located at the Hynes convention center in Boston. 

Although both events featured an impressive list of topics and tracks, other than the keynotes I spent the majority of my time meeting and talking to people.   One of my goals was to figure out how Sun can better work with Fedora to get more of our software into their distro. 

A few key Fedorans: Max Spevak, Dennis Gilmore, Tom "Spot" Callaway, Jeremy Katz, Paul Frields, Jesse Keating. 

President and CEO Jim Whitehurst chats with Fedora board member, Karsten Wade, …

If you are attending Usenix 2008 at the Sheraton Hotel in downtown Boston, you can meet me and ask your burning MySQL questions at my “The Guru is In” session. On Friday, June 27th, 2008 from 2 - 3:30 pm in Constitution B, I will be helping folks out by optimizing queries and schemas, teaching general principles of working with MySQL databases, and answering (to the best of my ability) any other question they may throw at me.

The event details are at:
http://www.usenix.org/events/usenix08/tech/#fri

Hope to see you there!