Use Pluggable Sorting Algorithms

Starting in version 3.0.2 of the MapR software, you can specify the DMExpress custom sorting algorithm from SyncSort for your MapReduce job. The JAR file dmxhadoop_mrv1_mapr.jar is installed along with DMExpress in the /lib subdirectory of your DMExpress installation directory.

Note:

Prerequisite

Before you use the DMExpress custom sorting algorithm, add the libMapRClient.so and libjvm.so to the LD_LIBRARY_PATH environment variable on each TaskTracker node and then restart Warden on each TaskTracker node.

  • To update the LD_LIBRARY_PATH, add the following text to opt/mapr/conf/env.sh file:export LD_LIBRARY_PATH=<full path to the directory libMapRClient.so>:<full path to the directory containing libjvm.so>:$LD_LIBRARY_PATH
  • To restart Warden, run the following commands: sudo service mapr-warden stop sudo service mapr-warden start