The next MySQL University session will take place this Thursday, 30th October. Giuseppe Maxia will get you up to speed with using MySQL Sandbox for quick and easy testing of MySQL.

This session will start at 15:00 Central European Time (14:00 UTC, 14:00 BST).

MySQL University is an educational program run virtually on the 'net. Sessions are open to anyone. MySQL University focuses on MySQL internals and on Sun technology that can be used in connection with MySQL, but we're open to hear your suggestions for other topics. Go to this page and fill in your suggestions!

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We all know with MySQL you can use ORDER BY with a list of columns to return an ordered set, e.g. ORDER BY name, type, state;
I often use the syntax ORDER BY 1,2; which I’m surprised that some people do not know about.

However I needed to do some selective ordering of a type field, I didn’t want to for example have a lookup table just to join for ordering. While contemplating a means of achieving this, I asked a work colleague, who I figured may have just experienced this problem before. Lone behold I became the student as I discovered there is a third syntax with ORDER BY, using expressions.

mysql> create table test(name varchar(10) not null, type varchar(10) not null);
Query OK, 0 rows affected (0.06 sec)

mysql> insert into test(name,type) values
('Apples','Fruit'),
('Bananas','Fruit'),
('Carrots','Veg'),
('Onions','Veg'),
('Beer','Liquid'),
('Water','Liquid'),
('Crackers','Food');
Query OK, 7 rows affected (0.00 sec) …

Since the day one when I joined Scribd, I was thinking about the fact that 90+% of our traffic is going to the document view pages, which is a single action in our documents controller. I was wondering how could we improve this action responsiveness and make our users happier.

Few times I was creating a git branches and hacking this action trying to implement some sort of page-level caching to make things faster. But all the time results weren’t as good as I’d like them to be. So, branches were sitting there and waiting for a better idea.

Few months ago my good friend has joined Scribd and we’ve started thinking on this problem together. As the result of our brainstorming we’ve managed to figure out what were the problems preventing us from doing efficient caching: …

I just came upon a pretty good Hadoop introduction paper posted on Sunâ€s wiki. Apache Hadoop is a free Java software framework that supports data intensive distributed applications. It enables applications to work with thousands of nodes and petabytes of data. Hadoop was inspired by Google's MapReduce and Google File System (GFS) (wikipedia). I wouldnâ€t call it an alternative to mysql – theyâ€re in completely different weight categories. I like …

As standard, MySQL allows replication from one master to multiple slaves, and that is a common scale-out scenario, but there have been a few comments recently, and some longer standing queries about having a setup that works the other way round, that is, multiple slaves replicating into a single master.

This a common enough scenario in data logging systems, where the data is collected locally and then distributed up to a central database, or in EPOS (Electronic Point of Sale) systems where you want the transactions logs from the tills logged up to the database at head office. There are many other situations where you want that merging of information.

Although MySQL doesn’t support what is called ‘multiple master, single slave’ solution, you can simulate the general approach by using a combination of replication and federated tables.

Replication allows for different table types on the master (the source of the data) …

MySQL University has been running for the last 18 months, and we’ve covered a wide range of topics, from the internals of MySQL right up to Amazon’s EC2, using MySQL in the Solaris/OpenSolaris Webstack and a description of the forthcoming MySQL Online Backup.

Personally, I think they’re great. Obviously many times I am scribe and am there for the sessions, but I listen to lots of the sessions anyway, and I’m yet to be disappointed by the content. What’s really great is that in all the cases the person you are listening to is probably the person that either developed, or helped drive development of the particular function, or, in the case of some of the external tools (EC2, for example), these guys are expert in it. The experience is not quite as thrilling as attending the MySQL User Conference, but the content is just the same.

The problem is that …

i5/OS doesn’t immediately strike you as the most natural environment for running MySQL, but in fact, there some advantages and benefits of making use of the hardware and i5/OS environment. The System i environment used with i5/OS is scalable, and the i5/OS itself provides lots of benefits over the control and separate of work.

Obviously another key advantage is that if you are already using i5/OS for your application, then being able to plug in MySQL into that equation on the same machine makes a big difference. For those companies and organizations that already have a business application on their server, you can use MySQL in combination with ODBC or more direct interfaces such as PHP to provide a web interface to your business application all in the same box.

MySQL works through PASE (Portable Application Solutions Environment) which allows AIX applications to run directly on i5/OS through a direct application binary interface. …

On his blog, Kaj Arnö has been writing about MySQL news, events, community and business developments for some time.

His most recent posts include (1)  a thank you note to David Axmark, one of the MySQL founders, for his 20-year contributions to MySQL and FOSS, and (2) an announcement regarding the move from MySQL contributor license agreement (MySQL CLA) to Sun Contributor Agreement (SCA), which is expected to be more contributor friendly.   

The current US financial situation has claimed a victim in the Web 2.0 world — Uber. I’m not sure if this is the first significant name, but it will not be the last site running MySQL where investors will be quick to cut losses and move on.

Indexes are a great way to improve performed in a MySQL database, when used appropriately.
When used in-appropriately the impact can be a degradation of performance.

The following example from Movable Type shows how when reviewing the slow query log I found numerous occurrences of Inserts take 3 or more seconds, with no reported lock contention time for this insert.

# Query_time: 3  Lock_time: 0  Rows_sent: 0  Rows_examined: 0
SET insert_id=6281;
INSERT INTO mt_comment
(comment_author, comment_blog_id, comment_commenter_id, comment_created_by,
 comment_created_on, comment_email, comment_entry_id, comment_ip, comment_junk_log,
comment_junk_score, comment_junk_status, comment_last_moved_on, comment_modified_by,
comment_modified_on, comment_parent_id, comment_text, comment_url, comment_visible)
VALUES (...)

The impact here, is that SELECT statements to the mt_comment table …