Some Hadoop and Hive Gotchas and Developer Tips

This is my log on several mistakes (some pretty dumb on the hindsight ) that I did while getting started with Hadoop and Hive some time back, along with some tricks on debugging Hadoop and Hive. I am using Hadoop 0.20.203 and Hive 0.8.1. localhost: Error: JAVA_HOME is not set This almost undecipherable and cryptic [...]

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Learn by Errors : Java + OSGi

Recently I worked on getting Apache Hive work inside an OSGi environment. While not proving to be a proverbial piece of cake (software right?.. Why am I not surprised? ), it led me through an assortment of Java and OSGi errors. Here I am listing some of them that bit me bit hard (no pun [...]

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So you are a programmer..

Been there. Done that. And suffered for that… Programming is fun. But there are some other associated stuff we programmers blissfully skip or procrastinate because they are not so cool. End result?… Somebody is going to get hurt at the end of the day and that somebody may very well be a ourselves. So here [...]

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Hector : Under the Hood

One of the past several days I decided to have a look how Hector, the Cassandra access library works under the hood. This was partially motivated by of the confusing the notions I had about some of API classes, specially Cluster. My initial impression was Cluster API class represents a Cassandra cluster but looking at [...]

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Some Cassandra gotchas

Here are some points to keep in mind when working with Cassandra. Have to use ordered partitioner if you want row keys in sorted order. Be aware that if the row keys are not distributed properly it would create hot spots since most of rows will be concentrated to several nodes. Columns are sorted using [...]

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Dangers of “resolution:=optional”

Recently I ran in to an interesting little problem with “resolution:=optional” OSGi directive. Basically what “resolution:=optional” says is that the even though the package imported with this directive is not present in the system  bundle would be resolved at run time. This is logical in case of compile time dependencies of the bundle not being [...]

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JMS Concepts – Persistent and Durable

I was reading up on JMS of late. The more I read the more I got confused about the usage of terms persistent and durable in the context of JMS. Then I found this blog which cleared my issues. Thanks Nigel for the great post. . Anyway here is the gist of that blog I [...]

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Maven Bundle Plugin – Tidbits

I use Maven Bundle plugin a lot since our projects are OSGi based. Basic idea I had of this plugin is that this plugin makes an OSGi bundle out of a normal jar (basically by augmenting the META-INF file) if we do declare exported and private package information correctly in it’s configuration section in the [...]

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Working with svn externals

Viewing current svn externals recursively. svn propget svn:externals -R Add a svn external svn propset svn:externals ‘conf http://sample.org/trunk’ . Note that conf folder should not already present in the svn. Also note the current working directory notation ‘.’ at the end. This will create a conf folder which is an svn external in current directory. [...]

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Some Common SVN Issues

Problem : svn: warning: Working copy ‘xxx’ locked Solution : Run a svn cleanup. If that fails.. 1. Get a svn diff of local modifications to a patch. svn diff > patch.diff 2. Delete folder containing locked resource path from the file system. Do not use svn delete. rm <folder-containing-locked-resource> 3. Run a svn update [...]

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