change db encoding?

hi,

for historical reasons ;)  (are there any other reasons),
we have a postgres db,
where the data are in iso-8859-15 encoding,
but the "database encoding" is iso-8859-1.

question(s):
1. is it possible to change the db-encoding?
2. if it remains like it is currently, when can there be problems?


thanks,
gabor