Improvements welcome!

create or replace function parse_fti_string (
        TEXT )
RETURNS TEXT AS '
my $result;
for (split /s+/, shift) {
    if (/^and$/i) {
        $result .= " &" if defined $result and $result !~ /[|&]$/;
    } elsif (/^or$/i) {
        $result .= " |" if defined $result and $result !~ /[|&]$/;
    } else {
        if (!defined $result) {
            $result = $_
        } elsif ( $result =~ /[(|&]$/ ) {
            $result .= " " . $_;
        } else {
            $result .= " & " . $_;
        }
    }
}
return $result;
' language plperl immutable strict;

P.S. a big thanks to David Wheeler for cleaning up my Perl.

1. Any advice given in the new version supercedes the advice given at General Bits. It's been a year and a half, we've learned a lot about PostgreSQL performance.
2. You'll notice on the new version that I did not include any of the "developer only" GUCs. This is on purpose; those are no longer included in PostgreSQL.conf, and before you use them you'd better be familiar with the main docs enough that you don't need help from me.
3. This document will be updated. Heck, even now Simon is testing whether or not commit_delay actually has any effect in 8.0.
4. The order of individual conf parameters is not exactly the same as the .conf file or the runtime-config page in the docs. This is because these two have become out of sync, something I plan to fix before 8.1. The order of the sections is identical, though, so just scroll a bit.