What's the best way to enforce a single output file per partition?
INSERT OVERWRITE TABLE <table>
It tried adding CLUSTER BY x,y,z at the end thinking that sorting will
force a single reducer per partition but that didn't work. I still got
multiple files per partition.
Do I have to use a single reduce task? With a few TB of data that's
probably not a good idea.
My current idea is to create a temp table with the same partitioning
structure. Insert into that table first and then select * from that table
into the output table. With combineinputformat=true that should work right?
Or should I make Hive merge output files instead? (using hive.merge.mapfiles)
Will that work with a partitioned table?