The sample code makes the following assumptions.

• The data in Greenplum Database format is located on the Hadoop Distributed File System on /demo/data/writeFromGPDB_42 on port 8081.
• This code writes the data to /demo/data/MRTest2 on port 8081.

1. Run a SQL command to create the writable table.

   =# CREATE WRITABLE EXTERNAL TABLE demodata 
      LOCATION ('gphdfs://hdfshost-1:8081/demo/data/MRTest2') 
      FORMAT 'custom' (formatter='gphdfs_export');
   

2. Author and run code for a MapReduce job. Use the same import statements shown in Example 1 - Read Custom-Formatted Data from HDFS.