There have been few bug fixes in Hive SerDes since Hive 1.0.0. Its good to update the Hive storage plugin to work with latest stable Hive version (1.2.1), so that HiveRecordReader can use the latest SerDes.
Compatibility when working with lower versions (v1.0.0 - currently supported version) of Hive servers: There are no metastore API changes between Hive 1.0.0 and Hive 1.2.1 that affect how Drill's Hive storage plugin is interacting with Hive metastore. Tested to make sure it works fine. So users can use Drill to query Hive 1.0.0 (currently supported) and Hive 1.2.1 (new addition in this JIRA).