Mar 24, 2014

Completed "Introduction to Databases" of Stanford Univeristy with "distinction"

I completed "Introduction to Databeses" of Stanford Univeristy with "Distinction", Yeah! This entry explains how this online course looks like.

Why did I participated in this course?

I was embedded software engineer and seldom use databases. Although, I was transferred to the Business Intelligence company as temporally trainee last October. Then, I often use several relational databases recently. So, I became to think I need to study database again. At that time, I found this course. Studying with book alone is a little bit hard, So I took this course.

Topics that this course covers

As I expected this course focuses on relational database theory, including SQL or table design, but they also cover non relational database including XML and JSON.
  • Relational Database Overview
  • XML Data
  • JSON Data
  • Relational Algebra
  • SQL
  • Relational Design Theory
  • Querying XML
  • Unified Modeling Language
  • Indexes
  • Transactions
  • Constraints and Triggers
  • Views
  • Authorization
  • Recursion
  • Online Analytical Programming
  • NoSQL Systems

How to participate in this course

In this course, every material became public from the beginning. You can start from any topic. Although, deadline of each assignment work is different. So, you should pick a topic that deadline is close first.

For each topic, you repeat the following procedure:
  • Watch some short videos that explain topics
  • Answer simple quizes(No score here)
  • Try to basic problems
    • multi-selection question(low score)
    • Programming work(middle score)
  • Try to challenge problems
    • Advanced programming work(high score)


When you answer each question, it is automatically scored. You can see how much percentage of scores you already got. If you solve all basic problems, you get 50 % and can complete the course. If you also try challenge problems and get 75 %, you can get "State of Accomplishment with Distinction".

Oh, everything is English!

It is really hard point for Japanese people. I actually worked in the office where no one speaks in English but now my all coworkers speak in English. So, no problems with this for me now.

Although, I felt difficulty when a teacher talked really fast about a topic that I was not familiar with. At the time, I had to watch the videos again and again. As a result, I tried to understand by solving some problems. Or sometimes I research some Japanese materials related to the topics.

How hard it was?

It depends on your skill and knowledge. It seems that it takes 3 hours every week to complete the course. You need 7 to 8 hours every week to complete with distinction. I sometimes had to study all day on Saturday or Sunday. If you work full time, you cannot take more than one course at the same time.

The important point to take an online course

If every material becomes public from the beginning, you should consider your private schedule and make a concrete schedule for the course. You might be struggling with difficult problems, so you should have some time to spare.

You should not postpone challenge problems even though their deadlines are late because you might forget about details when you are back to the problems :)


Have fun with an online course!!

Mar 23, 2014

"Fluentd: Open Source Log Management" by Sadayuki Furuhashi, Treasure Data at SF Metric Meetup

Sadayuki Furuhashi talks about Fluentd: Open Source Log Management from Librato on Vimeo.

This is a participation report for the SF Meetup. This meetup is probably data analysis for server administration. A log management is really far from my current job but I have been interested in fluentd since I knew that it is good approach to make data collection easy. And this is a good chance to hear about it from the founder. So, I participated in this.

About SF Metric Meetup

In the 21st Century successful teams are data-driven. This monthly meetup provides a forum for monitoring geeks to gather and trade new ideas, data, and war stories. If you love data, this meetup is for you! (cited from

About the speaker

Sadayuki Furuhashi is an architect and founder of Treasure Data. He is also a founder of some open source projects including fluentd.

About fluentd

Fluentd is extensive log management tool written by Ruby. Nowadays, the major web tech companes produce millions of lines of logs every day and their analysis sever operational status with the logs. Fluentd makes this collection/shape/analysis process easier. 

What they tried to do in this meetup

This time he came to the meetup with his coworkers of Treasure Data. I talked with some his coworkers about their business. They are trying to make his open source projects, including Fluentd, MessagePack popular through some meetups, before providing charged service. I realized that it is important to have this kind of networking opportunity and talk about own products to potential customers. I keep paying attention to their products and services.

Remote debugging for Tomcat and IntellJ on Max OS X

IntellJ supports remote debugging for Tomcat. It is really convenient for debugging. This entry shows how to adopt remote debugging with Tomcat and IntellJ.

My dev environment

  • Max OS X 10.9.2
  • Java 1.8.0
  • Tomcat 8.0.3

Set up

  1. Create a new file called <Tomcat install directory>/bin/ (This file will be automatically read by
  2. Add the following content to 8080 is a port number for Tomcat. Please specify for your tomcat.
    • CATALINA_OPTS="-agentlib:jdwp=transport=dt_socket,address=8080,server=y,suspend=n"
  3. Start Tomcat normally using

  1. Select "Run -> Edit Configuration" then "Run/Configuration" screen is open.
  2. Specify "Name" like "Tomcat".
  3. Specify "Port", which is the same number as Tomcat's port numer


  1. If you want to start debugging on IntellJ, just select "Run -> debug 'Tomcat'". 
  2. If IntellJ shows a message like below, you are already connected.
    • Connected to the target VM, address: 'localhost:8080', transport: 'socket'
  3. Now you can debug. Please refer here for more detail about debugging by IntellJ.