The Certified MySQL Associate Exam is a general overview of the MySQL database. It is designed for those new to databases and/or MySQL.

The subject of transactions has caused a few folks to stumble on their exams. For someone with a background in programming where you change data and it stays that way, transactions take a little effort to understand.

The usual example is a payment at a bank. A pays B 100 units. If something happens between the time the system takes the 100 out of A's account and puts it into B's account, there is a large chance that both A and B will not be happy. So the subtract 100 and add 100 are treated as one unit and either both have to be completed as a unit or not at all.


So all or nothing.

You type START TRANSACTION, input the needed changes, and COMMIT. And your changes are done as one to your database. Or half way through you realize that something is …

I've been reading a few blog postings such as Kore Nordmann's ActiveRecord sucks and Mike Seth's ActiveRecord sucks, but Kore Nordmann is wrong.ActiveRecord is fine.  It is a tool that does just what it's designed to do.  What sucks is when developers try to make it do other things than what it's intended to do.I worked for Zend, managing the Zend Framework project through its 1.0 release.  I

The upcoming 5.1.25 release will see a change with regards to MySQL Cluster:

MySQL 5.1.25 binaries will be released without Cluster support.

This is due to a change in the development cycle of MySQL Cluster. The work on Cluster specific features is largely independent from the rest of the MySQL Server, which has resulted in our decision to release MySQL Cluster separately from the rest of the MySQL Server, effective with MySQL 5.1.25.

This change just goes for the binaries, though. Let me reassure you that:

• Sun is still releasing MySQL Cluster under the GPL, as before.
• MySQL 5.1 source code will still include Cluster, and you can download and compile it with …

I have written a Configuration Tool for MySQL Cluster.
It is located on www.severalnines.com/config

The configuration tool lets you:

• Configure a Cluster based on MySQL Cluster 6.2 or MySQL Cluster 6.3
• The number of data nodes, mysqlds, and management servers
  
• Chose how much DataMemory to allocate for the data nodes
• Specify on which hosts to install the software on etc etc

Finally, configuration files (config.ini and my.cnf) and a set of scripts are generated based on your input and emailed to you.

With those scripts you can then:

• Download and compile 6.3
• Distribute the Cluster binaries onto the hosts you have specified)
  
• Bootstrap the system (create directories, mysql user account, install mysql database, configuration …

I have finally publicly released Federated ODBC Storage Engine, something I did most of the development for last year, then became extremely busy with work and other projects. I have heard of interest for this engine from several people, and I really enjoyed working on this project as it enables having a storage engine that can actually connect to a variety of data sources.

Last year I was able to connect it to a PostgreSQL table, but ran into a lot of headaches trying to get other RDBMS ODBC drivers working with it. A lot of the problem is that I need to make the SQL statements the storage engine builds very standard. I had to revert the code a bit to get it to work with the latest MySQL 5.1.21, so I lost some of that work to make the SQL generic. The other issue is that to test with other databases, you need to be somewhat fluent in setting up each one and getting it's ODBC driver working correctly, which takes time away from …

The 98th edition of Log Buffer, the weekly review of database blogs, has been published on Jeff’s SQL Server Blog.

Log Buffer is a shared project of the DBA blogging community, so you’re welcome to edit and publish an edition yourself. LB’s 100th anniversary edition is still up-for-grabs (and there’s plenty of room besides that), so read the Log Buffer homepage and the guidelines, and then email me.

Here’s Jeff Smith’s …

To some, Google has long been a champion of open source, hiring top open-source developers and contributing to a range of open-source projects, in addition to its Summer of Code. To others, Google has been the worst enemy of open source, bumping AGPL-based code of its Code.Google.com and only selectively contributing back to the projects like Linux and MySQL from which it derives benefit.

I've been in both camps. One thing is increasingly clear to me, however: Google is opening up to open source.

Earlier this week, I noted its …

A few years ago a backdoor was found in Firebird, the open source fork of Interbase, that already existed in the original Interbase product and was still in the version of Interbase that was sold at the time. Nowadays this is fixed, but it was kind of scary that a company would add a backdoor and then totally forget about it, why else would they not have removed it before open sourcing (after all a backdoor only works through obscurity)? Anyways the other day another security issue (this sort of thing happens to the best of them) in Interbase that was fixed in January in Firebird already.

The security issue has been long disclosed. Now why on earth would the Interbase …

Performance improvement:

* Earlier MONyog was semaphore intensive. That could result in reaching the ‘limit of semaphores that can be created by the kernel’ in some systems. MONyog 2.04 will use less semaphores. Another symptom was that a large number of small and zero-size files could be left behind (in system TEMP folder on Windows and in MONyog/bin folder on Linux). This is also solved with this.

Downloads: http://webyog.com/en/downloads.php
Purchase: http://webyog.com/en/buy.php

Bug fixes:

* Structure Sync could miss the concluding quote around column comments. This bug was introduced in 6.5.
* Migration from SQL Server could fail with empty tables.
* Migration (UPDATE and DELETE) triggers could fail with specific schemas on source (afffected were small tables with short column types only - like integers and very short string types). This bug was introduced early in 6.x with the full Unicode support added here.
* Migration could generate non-matching columns-count with specific schemas. This was also introduced early in 6.x
* Message about ?Successful rows? could display twice in Migration (sja.log). Note: This was a cosmetical issue with the message only. Rows were only migrated once!

Downloads: http://webyog.com/en/downloads.php
Purchase: …