Is it a big deal to change the user the DB runs under?

Just wondering if anyone has done this:
Change the user the DB runs under from postgres to apache on a
established server?
I would think I would just change ownership on all the data dir files
and modify the startup script in /etc/init.d/postgresql.

Reason is I need a plperlu procedure to generate a dir listing for a
Kylix CGI web app and the directories in question are limited to the
user and group apache,
hence my plperlu proc can't list the contents.  I also can't set the
other permissions because I don't want any other users peaking around.

Or is there a way to have the plperlu procs to run as a different user?
I have been looking though the plperl docs but have not seen anything
like that.

Thanks,

--
Tony