Rules for Hive append
I noticed in article https://cwiki.apache.org/confluence/display/Hive/Streaming+Data+Ingest that you are not supposed to add data to a Hive table other than adding a new partition. Is there a formal description somewhere about the rules for this? For example, is it allowed to add to an existing HDFS file for an external table? Is it permissible to change a file while applying zookeper locks? Do these limitations also apply to adding data with INSERT INTO statements?