It would be good if Avro would permit one to still read data if a type or field name has been changed. I propose we add a notion of name aliases. Aliases could be listed for every named type and for record fields. The writers schema would be permitted to contain any of the aliases.
In general, this permits one to construct schemas that can read different types into a single type. One could use this not just to handle renamings, but also to join different datasets. For example, if two datasets each contain differently named records with a date and an ip address field, this could be used be used to project these both to a single record with just those fields.