How many of you use the mysql command-line client?  And did you know about the pager command you can give it?  It's pretty useful.  It tells mysql to pipe the output of your commands through the specified program before displaying it to you.

Here's the most basic thing I can think of to do with it: use it as a pager.  (It's scary how predictable I am sometimes, isn't it?)

PLAIN TEXT SQL:

1. mysql> pager less
2. mysql> SHOW innodb STATUS\G

For big result sets, it's a pretty handy way to be able to search and scroll through. No mouse required, of course.

But it doesn't have to be this simple! You can specify anything you want as a pager. Hmm, you know what that means? It means you can write your own script and push the output through it. You can't specify arguments to the script, but since you can write your own, that's not really a …

Over the weekend I received a few emails asking for sample questions for the four MySQL Certification exams. There is a CDROM that comes with the MySQL 5.0 Certification Study Guide that covers the Developer and DBA Questions. The MySQL 5.1 Cluster Certification Study Guide (next edition due any day) has questions at the end of every chapter.

And there are questions that are just slightly modified from each ofthe four exams at http://www.mysql.com/certification/selftest/core/index.php

Last week at the Red Hat Summit in Boston, Jaspersoft announced their new version 3 suite, aimed at taking the company beyond their namesake widely-used reporting system. This latest version focuses on ad-hoc BI with a more flexible "Web 2.0" AJAX interface making it easy to build dashboards via drag and drop. By creating metadata domains, the eliminate the need for users to understand the underlying database schemas and queries. You can also easily embed the dashboard in any web application. JasperSoft's latest update appears to be a significant improvement in making open source BI offerings more competitive in the... READ MORE

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, …

My post on what it’s like to write a technical book was a stream-of-consciousness look at the process of writing High Performance MySQL, Second Edition. I got a lot of responses from it and learned some neat things I wouldn’t have learned if I hadn’t written the post. I also got a lot of questions, and my editor wrote a response too. I want to follow up on these things.

Was I fair, balanced and honest?

I really intended to write the post as just “here’s what it’s like, just so you’re prepared.” But at some point I got really deep into it and lost my context. That’s when I started to write about the things that didn’t go so smoothly with the publisher, …

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.