How to create an index using a function???

Hi -
    I have a table that has a varchar field (fname).  I'd like to
create an index on UPPER(fname), but am running into problems...

What I don't understand is that I can do "SELECT UPPER(fname) FROM
mytable" and it works just fine.  I also tried creating a SQL function
that did upper for me, but then the create index complains I can't use SQL
functions this way.

Hmm... I just tried creating a plpgsql function and now I can create the
index just fine...

Is this the only way to do it?  How come there's no
UPPER(varchar) function?

Just curious...

Thanks!

-philip

devloki=> create index foo on rolo_entry (UPPER(fname));
ERROR:  DefineIndex: function 'upper(varchar)' does not exist
devloki=> create index foo on rolo_entry (UPPER(varchar(fname)));
ERROR:  parser: parse error at or near "varchar"
devloki=> create index foo on rolo_entry (UPPER(text(fname)));
ERROR:  parser: parse error at or near "("
devloki=> create index foo on rolo_entry (UPPER(text fname));
ERROR:  parser: parse error at or near "fname"
devloki=> create index foo on rolo_entry (UPPER(fname::text));
ERROR:  parser: parse error at or near "::"
devloki=> create index foo on rolo_entry (UPPER(CAST(fname AS TEXT)));
ERROR:  parser: parse error at or near "cast"

devloki=>
devloki=> create function varcharupper(varchar) returns text as '
devloki'> begin
devloki'> return upper($1);
devloki'> end;
devloki'> ' LANGUAGE 'plpgsql';
CREATE
devloki=> select varcharupper('test');
 varcharupper
--------------
 TEST
(1 row)

devloki=> create index foo on rolo_entry (varcharupper(fname));
CREATE
devloki=>