Implementing a custom Hadoop key type
The instances of Hadoop MapReduce key
types should have the ability to compare against each other for sorting purposes. In order to be used as a key
type in a MapReduce computation, a Hadoop Writable
data type should implement the org.apache.hadoop.io.WritableComparable<T>
interface. The WritableComparable
interface extends the org.apache.hadoop.io.Writable
interface and adds the compareTo()
method to perform the comparisons.
In this recipe, we modify the LogWritable
data type of the Implementing a custom Hadoop Writable data type recipe to implement the WritableComparable
interface.
How to do it...
The following are the steps to implement a custom Hadoop WritableComparable
data type for the HTTP server log entries, ...
Get Hadoop MapReduce v2 Cookbook - Second Edition now with the O’Reilly learning platform.
O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.