The latest from the MySQL community

Pingdom, an online web site monitoring service, surveyed 7 massive sites to determine what infrastructure software they're running.  The sites included Meebo, YouSendIt, Alexaholic, TechCrunch, FeedBurner, iStockPhoto and Vimeo, all of which are high volume Web 2.0 sites.  As it turns out the LAMP stack is being used in 6 out of 7 of these sites. According to the article, MySQL dominates the database selection among high volume web sites:

With open source ruling the game it shouldn?t come as a surprise that the database of choice for all but one of the sites is MySQL, the ultra-popular Swedish open-source database.

?The features that you get for free on MySQL, with replication, in-memory and fault-tolerant databases (if using MySQL cluster), transaction support, and the wicked performance, cost thousands of dollars with …

The price for a 160 Gbyte disk will be around USD 15'000. This is still a bit expensive. But the access time is around 0.5 ms (both for reading and writing) which is around 10 times faster than a normal 15'000 rpm SCSI disk! The disk has NO cache because it is a cache itself (according to the supplier. Maybe this will change in the future). And the lifetime of a cell is > 5 mio writes. For the same performance one needs usually an array of around 10 disks. If your database is heavily write-I/O bound you should consider this solution.

It's hardware that makes a machine fast. It's software that makes a fast machine slow --Craig Bruce

One of the most common activity in a data warehouse environment is loading data into the database. The volume of data to be loaded is large compared to a transaction processing system. Tens or hundreds of megabytes of data may be need to be loaded in a data warehouse environment from one file. Compare this to one transaction, which is probably less than a kilobyte, in the transaction processing environment. The large throughput required for data warehouse data loads is achieved by:

1. using database utilities built specifically for the purpose, as opposed to the common SQL INSERT command; and
   
2. aggressive parallelism: task, …

MySQL Table Checksum is a tool to efficiently verify the contents of any MySQL table in any storage engine. You can use it to compare tables across many servers at once. The output is friendly and easy to use, both by eyeball and in UNIX command-line scripts. The provided MySQL Checksum Filter helps you winnow output so you only see tables that have problems. MySQL Table Checksum Following up on my earlier article about how to calculate a table checksum in MySQL, I’ve integrated that methodology, with improvements suggested by the commenters and others, into a single easy-to-use tool.

Klick on the image for the story. :)

I'm a GNOME user, but on my brother's suggestion I tried Amarok a month or so ago, and never looked back. I've used most of the popular music players for linux as well as iTunes & WMP, and I'd actually call Amarok the best on any platform. It's not even close.

One really nice feature is the database integration. I think every application should have this option, and not just because I work for a database company. Amarok can keep all its information in a MySQL database, and that includes the song lyrics it pulls down from the web.

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We often recommend to our clients to convert their current database from MyISAM tables to InnoDB.
The transfer by itself in most cases is almost plain, however the application can be broken by new unexpected errors
1205 (ER_LOCK_WAIT_TIMEOUT)

Lock wait timeout expired. Transaction was rolled back.

1213 (ER_LOCK_DEADLOCK)

Transaction deadlock. You should rerun the transaction.

It is not hard to handle these errors, but you should be aware of.
This is some thing we do in our PHP applications:

PLAIN TEXT CODE:

1. class mysqlx extends mysqli {
2.  
3. ...
4.  
5.   function deadlock_query($query) {
6.           $MAX_ATTEMPS = 100;
7.           $current = 0;
8.           while ($current++ <$MAX_ATTEMPS) …

I've been given the go ahead to release my NDB/Connectors code. These connectors wrap the NdbApi for a variety of languages, including Python, Perl, Java and C# at the moment. I'm managing development using Launchpad, so go to

https://launchpad.net/ndb-connectors

To get the latest version or status of the code. If you would like to contribute, feel free to branch a copy of the source using bzr and send me a revision bundle. There is also an ndb-connectors team on launchpad you can join if you'd like to participate more directly in the development. For either of these options to work, you need to first sign the MySQL Code Contributor License Agreement to assign copyright of your contributions to MySQL, Inc.

I hope to have a mailing list set up soon for discussion.