my $s0 = PublicInbox::SearchIdx->new($self->{ibx}, 0, 0);
if (my $xdb = $s0->idx_acquire) {
my $n = $xdb->get_metadata('has_threadid');
my $s0 = PublicInbox::SearchIdx->new($self->{ibx}, 0, 0);
if (my $xdb = $s0->idx_acquire) {
my $n = $xdb->get_metadata('has_threadid');