Last week I spent a half day at an SDForum think tank meeting "The Future of Open Source."  It was an invitation-only gathering of around 50 execs from the open source industry with a smattering of lawyers, VCs, corporate users and large IT companies including Microsoft, Novell, SAP, Sun, Symantec and Bank of America. The open source companies represented included providers such as Alfresco, BlackDuck, Collabnet, Covalent, Eclipse, Intalio, Funambol, JasperSoft, MySQL, Olliance Group, Optaros, OpenLogic, OSDL, SugarCRM, Zimbra, Zmanda and others.  A few companies were conspicuoulsy absent: JBoss, Red Hat, Sleepycat.

2006 will be a telling year for open source.  At MySQL …

A few recent books:

"Foundation for Future Database Systems. The Third Manifesto" by C.J. Date and Hugh Darwen.
An interesting and controversial book. In many cases completely rejects some practical arguments for the sake of purity of the model. A funny book too, as according to it, SQL is not a true relational language, which is a good reference to use when fingers are pointed at MySQL not being a relational database. Also gave a valuable insight why Bug#5719 should not be fixed. Despite this high appraisal, I don't think the book matches its title.

"C++ Coding Standards" by Herb Sutter and Andrei Alexandrescu.
A must-have book for C++ programmers, 200 pages of best programming style practices: basically, a summary of well-known sources, …

I'd like to give you my thoughts about the ENUM data type, which has strongly been discussed in various blog articles recently.

Ronald Bradford showed a nice way how to set up a reference table that's combined with the original table via foreign key constraints. I think, he's right that this is a more proper way to restrict a field to a range of allowable values - read here: http://blog.arabx.com.au/?p=87.

However, I still believe, if you only have up to maybe 5 or 6 values that very likely never change, the ENUM data type does a great job. It's easy to handle and it does exactly what it's supposed to do.

But even though more than 65,000 different values are allowed in an ENUM field, I think it shouldn't be used for many different values - in that case it's probably a better choice to set …

After trying to emulate check constraints with a trigger yesterday, I have now tried out if it works to enforce data integrity with views, as Arjen Lentz described it in this article: http://arjen-lentz.livejournal.com/49881.html.

I created a little table and a view with a WHERE clause that defined the conditions - and I added the WITH CHECK OPTION clause:

mysql> CREATE TABLE checktest (
    ->   id INT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY,
    ->   val INT UNSIGNED NOT NULL);
Query OK, 0 rows affected (0.00 sec)

mysql> CREATE VIEW v_checktest AS
    ->   SELECT id, val FROM checktest
    ->   WHERE val >= 1 AND val <= 5
    ->   WITH CHECK OPTION;
Query OK, 0 rows affected (0.00 sec)

mysql> INSERT INTO v_checktest (val) VALUES (2);
Query OK, 1 row affected …

I'm not sure how I missed Danny O'Brien's presentation at Oscon last year "On Evil." At any rate, it's now available on the ITConversations podcast.  The whole thing is about 15 minutes long and is a tongue in cheek look at good and evil in the open source world including mentions of all the hot topics: GPL licensing, Google, Maureen O'Gara, Ruby, Perl, Linus Torvalds and the ultimate evil: Software Patents. 

For those who aren't yet into podcasts, consider giving ITConversations a listen.  It's got some of the best content out there on a wide range of tech topics.  Next to Engadget and Phedippidations (don't ask) it's one of my favorites.  I'm hoping our Community guys will take up the mantle and develop a regular MySQL podcast in …

I guess it was punishment for falling off the wagon and letting my inbox get so many messages which were not filed away. Yesterday the email server had a database crash and every single email in every single one of my inboxes was marked as unread. I use IMAP with server-side filters (currently sieve, used to be procmail) to sort my incoming mail into about 40 different mailboxes, so you can imagine how I suddenly feel a bit lost and unsure about which things I’ve already read.

In happier news, quickfile is another reason to love thunderbird. Now I just need to find a way to back up all my IMAP mailboxes into a MySQL database so that I can have better backups and analysis, and I’ll be happy(I’ve realized that I’m unconditionally happy).

We’re getting a bunch of new users signed up to the MySQL user group in …

Today, I got yet another interesting question from a friend who has 30,000 rows with 10,000 unique values in a table and needs to query the data in a random order. He asks:

If I change my column type to enum, Will it make any difference in performance of my application?

"I don't think so," was my immediate reaction.

I know enum, though not standard in SQL, makes it efficient to store data but I am not sure whether it would have any effect on the query processing speed. Enum, I believe is limited to 65,536 possibilities.

On a side note, I recently noticed while playing around with Ruby on Rails that enum fields were not supported. Need to make it a part of standard SQL.

While looking for further clarification, I also found Ronald's post titled "To enum or not to enum." He presents his three reasons on why he doesn't …

Today, Mike opened my eyes as to why not having open comments can be costly, especially if you seek an answer.

So Mike, from now on you don't have to penalize me by not posting a comment. I am pleased to announce that comments are now open to anyone, not just the registered blogger.com users.

Big thanks to the following for their almost immediate support.

• Mike Hillyer for "Updating Another Table With MySQL Triggers"
• Markus Popp for …

That's amazing - almost like a chain reaction! Suddenly, everybody at Planet MySQL is writing something on triggers.

Well, to all those that want to try it too - that is - have a trigger perform an insert or update in anohter table here's a little tip that might be of use.

Suppose our trigger table has got an auto_increment column, and you'd want to be able to get your hands on the value of that item, what should you do? The answer was a bit of a surprise to me...

Suppose we have to tables, A and B and we want to have a trigger on A that inserts into B:
So, we need to someway transfer the generated id value for A into the corresponding field in B. Normally, you'd resort to the LAST_INSERT_ID, but this does tnot work inside a trigger.

Instead, use the new. pseudocolumn. That …

So I am listening to a talk by Rusty on talloc(). Its a memory allocation system.

Sounds great.

My question is, why do people keep writing these things? Apache has the same thing, its called APR. MySQL has mysys, GNOME has one as well (which MySQL uses for its GUI tools), and I've seen several others over the years.

Oh well... perhaps I will go write a string class, or yet another CMS system.

Why isn't this a completely annoying talk? Because Rusty is a great presenter :)