+# L<perldata/"Version Strings">
+my $v = eval 'v'.$over->{dbh}->{sqlite_version};
+SKIP: {
+ skip("no WAL in SQLite version $v < 3.7.0", 1) if $v lt v3.7.0;
+ $over->{dbh}->do('PRAGMA journal_mode = WAL');
+ $over = PublicInbox::OverIdx->new("$tmpdir/over.sqlite3");
+ is($over->dbh->selectrow_array('PRAGMA journal_mode'), 'wal',
+ 'WAL journal_mode not clobbered if manually set');
+}
+
+# ext index additions
+$over->eidx_prep;
+{
+ my @arg = qw(1349 2019 adeadba7cafe example.key);
+ ok($over->add_xref3(@arg), 'first add');
+ ok($over->add_xref3(@arg), 'add idempotent');
+ my $xref3 = $over->get_xref3(1349);
+ is_deeply($xref3, [ 'example.key:2019:adeadba7cafe' ], 'xref3 works');
+
+ @arg = qw(1349 2018 deadbeefcafe example.kee);
+ ok($over->add_xref3(@arg), 'add another xref3');
+ $xref3 = $over->get_xref3(1349);
+ is_deeply($xref3, [ 'example.key:2019:adeadba7cafe',
+ 'example.kee:2018:deadbeefcafe' ],
+ 'xref3 works forw two');
+
+ @arg = qw(1349 adeadba7cafe example.key);
+ is($over->remove_xref3(@arg), 1, 'remove first');
+ $xref3 = $over->get_xref3(1349);
+ is_deeply($xref3, [ 'example.kee:2018:deadbeefcafe' ],
+ 'confirm removal successful');
+ $over->rollback_lazy;
+}
+