We just started a project for a client that involves Cassandra.

If you’ve been living under a rock and don’t know what Cassandra is let me tell you :)

Cassandra is a “second-generation distributed database” that was built for web scale. Its is one of the many distributed nosql databases that appear everywhere lately like mushrooms after a heavy rain :).

What sets Cassandra apart is that it comes from a recognizable entity - Facebook.

But I digress. This is not meant to be a Cassandra introduction, there are enough of those on the net. I Just created a new nosql section on this blog where I’m going to post various tidbits of information about cassandra (and probably others) as I learn them while working on this new project.

Here is the first one:

Cassandra gem is just an installer

If you are on Mac OSX and interested in Cassandra you probably know that its just a gem installation away (almost):

gem install cassandra

First thing to note though is that this will not install Cassandra. It will install cassandra installer! I got bitten by this when I took my laptop with me to my doughter’s dancing class. You see, parents are not allowed “in the room” to not interfere with the process :), so I have 45 minutes to find myself something to do each time. I installed cassandra gem at home and intended to play with Cassandra while there. Not so fast. When I run cassandra_helper cassandra which is supposed to start a test cassandra instance it went to connect to a github repository to download and install the actual database. Duh!

and the 2nd one:

Use java preferences

When I got back and finally built Cassandra I got the following message when starting it for the first time:

~ > cassandra_helper cassandra
Set the CASSANDRA_INCLUDE environment variable to use a non-default cassandra.in.sh and friends.
(in /Library/Ruby/Gems/1.8/gems/cassandra-0.5.6.2)
You need to configure your environment for Java 1.6.
If you're on OS X, just export the following environment variables:
  JAVA_HOME="/System/Library/Frameworks/JavaVM.framework/Versions/1.6/Home"
  PATH="/System/Library/Frameworks/JavaVM.framework/Versions/1.6/Home/bin:$PATH"

First thing to note is that just typing JAVA_HOME="/System/Library/Frameworks/JavaVM.framework/Versions/1.6/Home" in the terminal wont help. You need to export it:

export JAVA_HOME="/System/Library/Frameworks/JavaVM.framework/Versions/1.6/Home"
PATH="/System/Library/Frameworks/JavaVM.framework/Versions/1.6/Home/bin:$PATH"

No need to export PATH as its already exported.

But there is a better and simpler way!

Start “Java Preferences” (find it in /Applications/Utilities, or just use spotlight):

Then reorder the entries in the bottom “Java Applications” section so that Java 6 will be the 1st:

Now cassandra starts right away w/o any exports:

~ > cassandra_helper cassandra
Set the CASSANDRA_INCLUDE environment variable to use a non-default cassandra.in.sh and friends.
(in /Library/Ruby/Gems/1.8/gems/cassandra-0.5.6.2)
CASSANDRA_HOME: /Users/vitaly/cassandra/server
CASSANDRA_CONF: /Library/Ruby/Gems/1.8/gems/cassandra-0.5.6.2/conf
Listening for transport dt_socket at address: 8888
...

Cool, now go write your killer application!