This post is continuation for previous post on hadoop sequence files. In this post we will discuss about Reading and Writing SequenceFile Examples using Apache Hadoop 2 API.
Writing Sequence File Example:
As discussed in the previous post, we will use static method SequenceFile.createWriter(conf, opts) to create SequenceFile.Writer instance and we will use append(key, value) method to insert each record into sequencefile.
In the below example program, we are reading contents from a text file (syslog) on local file system and writing it to sequence file on hadoop. Here, we are using integer counter as key and each line from input file as value in sequence file format’s <key, value>.
For verification of (key, value) pairs in sequence file, we are printing first 50 records onto console. Copy below code snippet into SequenceFileWrite.java program file.
Compile this program and build jar file (Say Seq.jar) and we will use this jar file to run SequenceFileWrite program on hadoop.
Run it with below command.