After directing a Devshed poster looking for a way to compute the number of months between two dates to the manual I decided to turn the solution posted in user comments by Isaac Shepard into a function, here it is:

1. DELIMITER $$
2. DROP FUNCTION IF EXISTS `test`.`months_between` $$
3. CREATE FUNCTION `test`.`months_between` (date_start DATE, date_end DATE) RETURNS INT
4. BEGIN
5. SELECT IF((((YEAR(date_end) - 1) * 12 + MONTH(date_end)) - ((YEAR(date_start) - 1) * 12 + MONTH(date_start))) > 0, (((YEAR(date_end) - 1) * 12 + MONTH(date_end)) - ((YEAR(date_start) - 1) * 12 + MONTH(date_start))) - (MID(date_end, 9, 2) < style="color: rgb(102, 204, 102);">(date_start, 9, 2)), IF((((YEAR(date_end) - 1) * 12 + MONTH(date_end)) - ((YEAR(date_start) - 1) * 12 + MONTH(date_start))) < …

Development of a more structured version is in progress. I just committed a set of changes to the repository that changes the current, rather monolithic, single-class design to what will be the first step of a more modular one.

Currently the generation of ALTER TABLE statements has been removed and the output format of the analysis is slightly different. But that is mere cosmetic.

What is much more important is that now the gathering of database schema information is based on a pluggable system, designed around an interface called IndexDescriptorProvider. Up to now I have just ported the MySQL 4 stuff that was already in the first version to this new architecture. Please feel free to have a look at it and tell me what you think.

Next thing I'll do is implement a provider based on the INFORMATION_SCHEMA database available in MySQL 5.x to see if I missed anything.

Go to …

I'm reading an interesting research paper (to be blogged later) that mentions a fact that I find pretty compelling:

In 2001 Debian included more than 55,000,000 lines of code, with an estimated (COCOMO) value of $1.9 billion.That's just Debian (and, as Wheeler notes, it grew to 230 million lines of code by 2005, putting its COCOMO price at $8 billion).

What number would we get to if we added MySQL (2M+ lines of code, I believe), JBoss, etc.? I can't even begin to come up with a rational number, but I'm guessing we're north of $50 billion. $50+ billion worth of free (as in cost and freedom) and open source software.

Priceless.

(Keep in mind that there's more to good software than code size. …

I'm reading a research paper [PDF] by Nicholas Economides (NYU) and Evangelos Katsamakas (Fordham) called "Linux vs. Windows: A comparison of application and platform innovation incentives for open source and proprietary software platforms." Long title, but the conclusion of the paper is relatively brief:

In our model, firms and developers invest to improve the quality of the platform or the application and expand the demand by users of these software products. When the operating system is proprietary, the platform provider and the application provider invest only in their own product to maximize their profit. When the operating system is open source, there is no platform provider firm, but the users invest in the platform to maximize their user surplus and their development reputation, which depends on the success of the platform measured by its …

best practices, database, internet, mysql, security, software, technology web

With recent posts by Frank Mash and Stewart Smith about password …

Back in May Dan Morgan was kind enough to invite me to do a guest lecture at the University of Washington about “Data Warehousing Basics.”  After having emailed these slides as a decent overview to a few customers lately, I realized they’d probably be useful online.  It is obviously a little light on content (their just slides) but they do provide some good “high level views” of dimensional modeling/DW/BI in general.  My employer, Pentaho, was generous enough to allow me time to build this presentation for the students at UW for which they, and I are grateful.  THANK YOU!

The online version: Univerisity of Washington Guest Lecture May 9
The PDF of …

Open source is democratic, open, real.

While I have a good sense for which Tech Tips would be useful, I’d also like to ask the community for what tips they’d like to see written up:

• Mondrian: Star Schema to OLAP cubes
  A very basic Star Schema with a Fact and Two Dimensions show how this is built into a Mondrian cube and how to built a “Pivot view” Pentaho report.
• Mondrian: Advanced MDX
  Sets, top, running totals, etc
• Kettle: Portable ETL
  Showing how to use paramater injection to make your Kettle solution (Jobs and Transforms) executable inside of Pentaho.
• Kettle: Custom rollups using Excel
  Showing how to build a dimension, reporting table, etc using a very easy to use interface for business users.
• Reporting: List of Values
  Show how to use the most unfortunately …

The 451 Group is calling for change in the business models of the so-called "stack providers." (OpenLogic, Spikesource, Sourcelabs, etc.) Dave and I have seen this coming for some time, and the vendors, themselves, have, too, as each has been tweaking its model over time.

(Dave has never been a big believer in Spikesource (here is his first assessment), though I've been more sanguine, and I've also skewed pro OpenLogic and BitRock.) …

James Montebello, a friend, a mentor, a fantastic engineer, and the person who introduce me to mySQL in 1999 passed away August 24, 2006.

I write this today in dedication to a great man. I also write this in appreciation for all the time we had together, and for guiding me on what are the right things to do.

He was among the 1st to believe in my designs

James you will be deeply missed.

I posted some Basic Documentation for MySQL Index Analyzer including a simple example. This is intented to get started with the tool without having to read the code.

Any ideas and suggestions for improvements are appreciated :)