Minor Description
When using call to Delete#deleteColumn(byte[], byte[]) to produce KeyValues that are subsequently written to HFileOutputFormat and bulk loaded into HBase, the Delete seems to be ignored. The reason for this is likely to be the missing (HConstants.LATEST_TIMESTAMP) timestamp in the KeyValue with type KeyValue.Type.Delete. I think the RegionServer than cannot delete the contents of the column due to mismatch in the timestamp.
When using Delete#deleteColumns everything works fine, because of different type KeyValue.Type.DeleteColumn.