Blog Posts
JETM - The easy way to monitor your Spring Application
Programming Tutorial
June 8, 2009 | COMMENTS

JETM stand for Java™ Execution Time Measurement Library, it’s an useful library to monitor your java application in a smart and easy way. Here is an overview on how to use JETM with a Spring application like in Red5.

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Using losetup and dd to secure sensitive data (encrypted block device)
Shell Case Study
July 13, 2008 | COMMENTS

My previous post was made a long time ago, so here is a draft that I finally decide to post. Let’s see how to secure some of your data with an encrypted block device using losetup and dd.

Steps will be :

  1. Create an image with dd
  2. Build a new device using the image with an encrypt algorythm by using losetup
  3. Format the device using mkfs.ext3
  4. Mount the device and start using it !

Of course, when you have mounted the device, your data are readable to anyone who have access to the mounted directory.

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MySQL - Impact of multiple column indexes misuse
Tips Case Study
February 13, 2008 | COMMENTS

Here is a quick picture about the impact of MySQL indexes misuse. At work, our developers made a new release of their search engine using MySQL fulltext indexes, unfortunately they didn’t implement it correctly. The impact was a huge load on all our database servers. To find the trouble, I had to redirect the SQL search flow to a specific server and check for the slow queries then reproduce it with EXPLAIN. Don’t need a long time to find that the search query did an invalid usage of the fulltext index and the "Match / Against" syntax. In fact, the fulltext index was a multiple column fulltext index, in such case you have to specify ALL the column present in your index, else the index won’t be used by MySQL...

MySQL - Fulltext Indexes (MATH / AGAINST)
Printing a sequence of letters or numbers
Shell Tips
January 14, 2008 | COMMENTS

Some times, while scripting in your favorite shell (I mean Bash !! 😃 you need to print a sequence of letters or numbers. Don’t write it yourself ! Script it using seq or curly braces !

nicolas@macvin:~$ seq 1 10
1 2 3 4 5 6 7 8 9 10
nicolas@macvin:~$ seq 0 2 10
0 2 4 6 8 10
nicolas@macvin:~$ echo {1..10}
1 2 3 4 5 6 7 8 9 10
nicolas@macvin:~$ echo {a..g}
a b c d e f g

Hope this will help you while doing a loop or building some hash directories :

nicolas@macvin:~$ mkdir -p test/{1..10}/{1..10}

Enjoy !

How to flush DNS Cache in Mac OS X ?
Shell Tips
January 3, 2008 | COMMENTS

Joy ! I just get my new [Mac Book Pro][1] (2Go RAM / 2,4Ghz Core 2 Duo / 160Go HDD / etc.). So I’m playing a lot with [VMware Fusion][2] and multiple host (debian, ubuntu, solaris, windows, etc.) with a great fluidity ! A big improvement for me who was working with an old DELL Laptop with 1Ghz Celeron and 512Mo of Ram...

But, while playing with my new laptop and my multiple virtual instances I needed to flush my DNS Cache. So, here come the tips :

With Mac OS X <= 10.4 :

macvin:~ root# lookupd -flushcache

With Mac OS X > 10.5 :

macvin:~ root# dscacheutil -flushcache

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