Export of a large table causes OOM in Metastore and Client

Running hive export on a table with a large number of partitions winds up making the metastore and client run out of memory. The number of places we wind up having a copy of the entire partitions object wind up being as follows:

Metastore

• (temporarily) Metastore MPartition objects
• List<Partition> that gets persisted before sending to thrift
• thrift copy of all of those partitions

Client side

• thrift copy of partitions
• deepcopy of above to create List<Partition> objects
• JSONObject that contains all of those above partition objects
• List<ReadEntity> which each encapsulates the aforesaid partition objects.

This memory usage needs to be drastically reduced.