Some of you may have run the mysql-test-run tool which is the MySQL test suite. But did you know there are actually multiple suites? If you just run the tool, you don’t get everything!

Check out the mysql-test/suites subdirectory. That’s all the stuff you don’t get when just running the tool normally. If you take a peek at the Makefiles, you will find a target test-bt (build team) which shows the extra calls and parameters for the additional suites.

OurDelta has had some interesting cases where a build that’s otherwise ok would fail when users tried the test suite on their installation. We reckon such a test should definitely pass, and thus we had some more homework to do. So now OurDelta builds with as many tests as exist enabled, on all platforms and architectures. Slow yes, but that’s not an argument to not test something, right? Failing tests are often indicative of other issues, so at the very least …

It may seem hard to believe, but I have seen DECIMAL(31,0) in action on a production server. Not just in one column, but in 15 columns just in the largest 4 tables of one schema. The column was being used to represent a integer primary or foreign key column.

In a representative production instance (one of a dozen plus distributed production database servers) the overall database footprint was decreased from ~10 GB to ~2 GB, a 78% saving. In total, 15 columns across just 4 tables were changed from DECIMAL(31,0) to INT UNSIGNED.

One single table > 5GB was reduced to under 1GB (a 81% saving). This being my record for any GB+ tables in my time working with the MySQL database.

Had this server for example had 4GB of RAM, and say 2.5GB allocated to the innodb_buffer_pool_size, this one change moved the system from requiring more consistent disk access (4x data to memory) to being able to store all data in memory. Tests showed …

So it turns out that a VPS server, while inexpensive, is a poor choice for a demo server of a product. So the Kontrollbase demo is now hosted on a Sun X4100 quad-opteron with 8G ram and some nice SAS disks. The new demo site is http://demo02.kontrollbase.com , the old one is located here if [...]

The EXPLAIN command is an important tool to review how a SQL query is executed and in this example includes what indexes are used.

By adding a covering index I ended up with the following EXPLAIN plan I was unable to explain. The end result was a boost in server performance which was the ultimate goal.

mysql> explain select max(md)  from e_r  where email = 'xxxx@gmail.com' and id = '36981';
+----+-------------+-------+------+---------------+------+---------+------+------+------------------------------+
| id | select_type | table | type | possible_keys | key  | key_len | ref  | rows | Extra                        |
+----+-------------+-------+------+---------------+------+---------+------+------+------------------------------+
|  1 | SIMPLE      | NULL  | NULL | NULL          | NULL | NULL    | NULL | NULL | Select tables …

One of the most asked questions is how to setup MySQL replication. The MySQL Reference Manual provides a good Replication How To as a starting guide on MySQL Replication 101.

MySQL replication has many uses including read scalability, backups, failover, online maintenance, upgrade testing and verification, software upgrades, alternative data or structure for performance queries and even benchmarking to name the popular uses.

When reviewing an installation of MySQL replication I use the following as part of my checklist of steps used for confirming your replication environment is operational.

Master Variables

• server-id – Replication will not work without this correctly set and unique
• log-bin – Pre-requisite for working replication
• log-bin-index
• max_binlog_size
…

I think I have mentioned Picok before on my blog. This is a system that lets users arrange and configure a number of portlets in order to be able to keep themselves up to date with what's going on in various web applications, similar to iGoogle and netvibes. The difference is of course that this system is entirely open source, so companies can install Picok in their intranet and give Picok direct access to all sorts of internal applications that they could not make available to iGoogle or netvibes. What makes this project all the more exciting is that this system was initially developed as a closed source application for the Raiffeisen bank in Switzerland. This was the first time for me, where I had the opportunity to be part of open sourcing such a large chunk of code.

One of the things we open source proponents mention as a plus point for open source is that developers do not easily get away …

Just a quick note to let the masses know that I will be hosting a MySQL University session tomorrow, based on the talk that I gave at the MySQL UC in April - Customizing MySQL Enterprise Monitor.

It will be at 14:00 UTC - so if you are at all interested in MEM, and want to know how to bend it towards your needs, then come along! I’ll see you there.

EDIT: OOOPS, it’s 13:00 UTC

While not a MySQL topic, as most of my readers view my MySQL Blog, my WordPress blog has been hacked? Has yours?

Like many, I’m sure you may have read about it like at Wordpress blogs under attack from hack attack but I was surprised when my custom permlinks did not work.

Being surprised I looked at Administrator accounts, and I found that there was one more number then being displayed in the list. I had to dig into the database to find the problem.

mysql> select * from wp_users where ID in (select user_id from wp_usermeta where meta_key = 'wp_capabilities' and meta_value like '%admin%');
+-----+-------------+------------------------------------+---------------+------------------------------+---------------------------+---------------------+---------------------+-------------+--------------+
| ID  | user_login  | user_pass                          | user_nicename | …

As I outlined in Part 1 MySQL Proxy can be one tool for performing SQL analysis. The impact with any monitoring is the art of monitoring will affect the results, in this case the performance. I don’t recommend enabling this level of detailed monitoring in production, these techniques are designed for development, testing, and possibly stress testing.

This leads to the question, how do I monitor SQL in production? The simple answer to this question is, Sampling. Take a representative sample of your production system. The implementation of this depends on many factors including your programming technology stack, and your MySQL topology.

If for example you are using PHP, then defining MySQL proxy on a production system, and executing firewall rules to redirect incoming 3306 traffic to 4040 for a period of time, e.g. 2 …

Just in case you missed the live event, we have a recording of the ZFS + SSD for databases webcast

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You can also download the slides from Slide share. Download Slides