For unbucketed tables DeleteReaderValue will currently return all delete events. Once we trust that
the N in bucketN for "base" spit is reliable, all delete events not matching N can be skipped.
This is useful to protect against extreme cases where someone runs an update/delete on a partition that matches 10 billion rows thus generates very many delete events.
HIVE-19890 all acid data files must have bucketid/writerid in the file name match bucketid/writerid in ROW__ID in the data.
OrcRawRecrodMerger.getDeltaFiles() should only return files representing the right bucket