Since MySQL Proxy 0.7.0 is soon to be released, I thought another brief tutorial would be helpful. Today we ran across a good use case, and so I wanted to pass this along. If you’ve not used Proxy yet, this is a great opportunity to get your feet wet with it and some Lua.

When queries are routed though MySQL Proxy from various servers, the MySQL Server only sees that the query came from the machine Proxy is running on.

So when you are viewing output of SHOW PROCESSLIST, you have no way of telling what server a particular query originated from.

However, this could be very useful information to have, especially to determine which server a particular long-running query is coming from at that particular moment in time.

mysql> show processlist;
+----+------+-----------------+------+---------+------+-------+------------------+
| Id | User | Host            | db …

In case you haven't noticed them yet ..
MySQL Proxy has a new release and moved it's public repo to Launchpad.

(Still Launchpad isn't open source yet .. a matter of time .. but in the meanwhile Jira and Confluence are sadly gaining adoption in the market)

In the devministration area there is a new Puppet module that automagically populates puppet managed machines in Zenoss , I've seen different people using Puppet to populate their Nagios configs, but adding Zenoss to the list is new.. so when will we see the Zabbix and Hyperic plugins ?

Oh yes.. and then there is Chef

A few days ago the mysql proxy tool was released (link) and it does exactly what the name would suggest. But it does boast a few features that have changed the development of the test creation tool.

• It has a Lua interpreter that allows user written scripts or modules to be run by the proxy. These scripts can intercept queries and responses between the client and the MySQL server, and also manipulate them in whatever way necessary. There are examples on the wiki of how to use the scripts.
• Instead of writing an entirely new command line client, we can use the standard mysql client and focus on the scripts that will intercept the client-server communication and translate that into test cases.

For these reasons the test creation tool will not be written in C/C++ but instead as Lua modules that the proxy will run. This will hopefully …

Ever wondered what your PHP application and MySQL actually do? An experimental mysqlnd branch will give you full access to the network communication stream. Using a custom PHP stream filter you can then intercept the communication ... but let's start at the beginning:

When talking about mysqlnd - the mysql native driver for PHP - we always mention the fact it's native in a way that we're, when possible, using PHP infrastructure. The most common example here is the memory management. By directly using PHP's memory we can avoid unnecessary copies of data from the MySQL Client Library's memory into PHP memory.

<?php
$mysqli = mysqli_connect("localhost", "root", "", "test");
$stream = mysqli_conn_to_stream($mysqli);
…

From a performance standpoint, sometimes even tightly tuned queries can cause a performance drag. The common problem here is not one of actual query performance, rather it is a function of:

- the velocity and frequency that a query is submiited for execution
- the total execution time of the aggregated executions

This could be symptomatic of an application not properly configured for caching (see Darren Oldag's blog on this!), or just overall poor design. Regardless of why, when or how we all know it happens. The trouble with this particular problem is that when a query is tuned, or very simple, it is usually not suspect for being a resource hog. Pulling aggregates for number of execs and total exec time for specific queries is a little tricky and labor intensive with the Slow Query Log, and not really a good …

One of the biggest problems I faced as a field DBA was defending my production databases against poorly performing SQL code. Talking to folks at the MySQL UC, during customer visits and trolling the MySQL forums/blogs confirms that this is a common problem and even more challenging when a performance problem pops up during times when no code promotions have taken place.

Traditional/popular way of finding bad SQL code
For MySQL DBAs the challenge to identify and isolate resource intensive SQL code is really two-fold; job #1 is to find the offending code (after that the chore becomes fixing it so it performs, but that is a topic for another post). Most MySQL DBAs have used the MySQL Slow Query Log ("SQ Log") at some point to help with job #1. For those not familiar, the SQ Log is enabled by starting MySQL with --log-slow-queries[=file_name] option. Once enabled the SQ Log captures queries that took longer than X seconds (user …

The following Lua scripts are the examples are from my MySQL Proxy @ OSCON 08 presentation.

analyze_query.lua

MySQL Proxy Analyze Query.

Requires MySQL Proxy Logging Module.

What is released is the Version for MySQL 5.0. A generic version for all MySQL versions is not yet released.

histogram.lua

This script is part of the standard MySQL Proxy examples.

Other Scripts

Additional Lua scripts from MySQL forge are available here.

Today I presented with Giuseppe Maxia of Sun Microsystems Inc at OSCON 08 on “MySQL Proxy: From Architecture to Implementation”. I was surprised to find that MySQL has a strong showing with a number of presentations this week.

Our talk covered the basics of MySQL Proxy, what’s coming in future features, and a number of examples of how I have used Proxy in consulting engagements to improve the information retrieval particularly for identifying performance problems.

Download Presentations Slides

I’ve been accepted to speak at the upcoming 2008 OSCON Conference in Portland Oregon July 21-25 2008, where I’ll be speaking with Giuseppe Maxia on MySQL Proxy. I haven’t seen a schedule yet, so I’m interested if there are any other presenters on MySQL topics!

In my opinion, the last MySQL Meetup group in London was a really good event. We met Marten Mickos, former CEO of MySQL and now Senior Vice President of Sun, David Axmark, founder of MySQL and Simon Phipps, Chief Open Source Officer at Sun.

The main questions to the guests were pretty expected: is it going to change anything in the licensing, the deployment and the platforms of MySQL? The single answer is a "No, nothing is going to change". No change in the licensing (Simon Phipps has clearly stated it), no changes in the Community and Enterprise editions (at least not in the near future) and no changes in the development for Linux, Windows, Solaris and other OSes. There will be more opportunities, instead, of spreading the database in environments that are not the common target for MySQL at the moment. We are definitely not going to inflate the server with a large set of barely …