Here's how I ran into this issue:
1) Created a SequenceFile by exporting data from Oracle using Sqoop.
2) Used 'sqoop codegen' to generate a Hive table script.
3) Created table under Hive using this script.
4) Under Hive, ran following command:
5) select count(*) from mytable;
Got 'QueryResult cannot be cast to org.apache.hadoop.io.WritableComparable'. When I looked at the generated source, it indeed does not implement this interface. I think it should.
I guess the workaround is to implement the 'compare' method in this interface. But shouldn't the code generation generate this in QueryResult?
Sounds like a bug to me -:) Either that or I am doing something really stupid - which is always a possibility. Please share thoughts. Thanks.