HIVE-3833 fixed the targeted problem and made Hive to use partition-level metadata to initialize object inspector. In doing that, however, it goes thru every file under the table to access the partition metadata, which is very inefficient, especially in case of multiple files per partition. This causes more problem for AvroSerde because AvroSerde initialization accesses schema, which is located on file system. As a result, before hive can process any data, it needs to access every file for a table, which can take long enough to cause job failure because of lack of job progress.
The improvement can be made so that partition metadata is only access once per partition.