alter table impact on view

Hello,

to my understanding, if I do alter table rename column, Postgres change the
name of the said column, and modify the views using that table so that they
keep working (NOT oracle behaviour..)
fine.
But if I alter table to change a column that is a varchar 20 into a varchar
21
postgres refuse saying that it cannot due to the return rule... using said
column

why ?? as the view is not a materialized object, the impact of the length
of a column of an underlying table do change the description of the view,
clearly, but I dont see where the difficulty is "hidden". Can someone
enlighten me?

thanks,

Marc MILLAS
Senior Architect
+33607850334
www.mokadb.com