+# used to keep track of used numeric mappings for v2 reindex
+sub tmp_clone {
+ my ($self) = @_;
+ my ($fh, $fn) = tempfile(EXLOCK => 0);
+ $self->{dbh}->sqlite_backup_to_file($fn);
+ my $tmp = ref($self)->new_file($fn, 1);
+ $tmp->{dbh}->do('PRAGMA synchronous = OFF');
+ $tmp->{tmp_name} = $fn; # SQLite won't work if unlinked, apparently
+ $fh = undef;
+ $tmp;
+}
+