Many thanks for the pointer. Running this (SqlSupport is a homebrew helper module):

use lib qw ( c:/perlmodules );
use SqlSupport;
my $dbh = connectpgdb(*,*,*,*,*);

my $query = "select id,post from blog where language = 'en'";
my $sth = $dbh->prepare($query);
$sth->execute || die "Could not execute MySQL statement: $sqlstatement
+";
my $rows = []; # cache for batches of rows

while( my $row = ( shift(@$rows) || shift(@{$rows=$sth->fetchall_array
+ref(undef,10_000) || []}))) 
{
    my $foo = 1;
}
$sth->finish();
[download]

It's saying the last bracket is unmatched. But my IDE shows every bracket has a mate, and I clipped the whole while loop from the DBI docs.