comparando strings no PostgreSQL

CREATE OR REPLACE FUNCTION unaccent_string(text) RETURNS text AS $$
my ($input_string) = @_;
$input_string =~ s/[âãäåāăą]/a;
$input_string =~ s/[ÁÂÃÄÅĀĂĄ]/A;
$input_string =~ s/[èééêëēĕėęě]/e;
$input_string =~ s/[ĒĔĖĘĚ]/E;
$input_string =~ s/[ìíîïìĩīĭ]/i;
$input_string =~ s/[ÌÍÎÏÌĨĪĬ]/I;
$input_string =~ s/[óôõöōŏő]/o;
$input_string =~ s/[ÒÓÔÕÖŌŎŐ]/O;
$input_string =~ s/[ùúûüũūŭů]/u;
$input_string =~ s/[ÙÚÛÜŨŪŬŮ]/U;
return $input_string;
$$ LANGUAGE plperl;

CREATE OR REPLACE FUNCTION unaccent_string(text)
RETURNS text
IMMUTABLE
STRICT
LANGUAGE SQL
AS $$
SELECT translate(
    $1,
    'âãäåāăąÁÂÃÄÅĀĂĄèééêëēĕėęěĒĔĖĘĚìíîïìĩīĭÌÍÎÏÌĨĪĬóôõöōŏőÒÓÔÕÖŌŎŐùúûüũūŭůÙÚÛÜŨŪŬŮ',
    'aaaaaaaaaaaaaaaeeeeeeeeeeeeeeeiiiiiiiiiiiiiiiiooooooooooooooouuuuuuuuuuuuuuuu'
);
$$;

create or replace function unaccent(text) returns text language plpythonu as $$
import unicodedata
rv = plpy.execute("select setting from pg_settings where name = 'server_encoding'");
encoding = rv[0]["setting"]
s = args[0].decode(encoding)
s = unicodedata.normalize("NFKD", s)
s = ''.join(c for c in s if ord(c) < 127)
return s
$$;