lib/PublicInbox/ExtSearchIdx.pm | 8 +++++---
 script/public-inbox-extindex    | 4 ++--

diff --git a/lib/PublicInbox/ExtSearchIdx.pm b/lib/PublicInbox/ExtSearchIdx.pm
index 778154a564b20433cf841adcd596ae121bb63ac7..07e646985a4715d273b2f7b7f80f2c0374179d7b 100644
--- a/lib/PublicInbox/ExtSearchIdx.pm
+++ b/lib/PublicInbox/ExtSearchIdx.pm
@@ -881,9 +881,11 @@ 		eidx_reindex($self, $sync);
 	}
 
 	# don't use $_ here, it'll get clobbered by reindex_checkpoint
-	for my $ibx (@{$self->{ibx_list}}) {
-		last if $sync->{quit};
-		sync_inbox($self, $sync, $ibx);
+	if ($opt->{scan} // 1) {
+		for my $ibx (@{$self->{ibx_list}}) {
+			last if $sync->{quit};
+			sync_inbox($self, $sync, $ibx);
+		}
 	}
 	$self->{oidx}->rethread_done($opt) unless $sync->{quit};
 	eidxq_process($self, $sync) unless $sync->{quit};
diff --git a/script/public-inbox-extindex b/script/public-inbox-extindex
index 17986f606e93f16872aa7e4df2d0ad72cad4fe59..f4ffda4b43703694a8da671ceb43416514dd4b33 100644
--- a/script/public-inbox-extindex
+++ b/script/public-inbox-extindex
@@ -23,12 +23,12 @@
 BYTES may use `k', `m', and `g' suffixes (e.g. `10m' for 10 megabytes)
 See public-inbox-extindex(1) man page for full documentation.
 EOF
-my $opt = { quiet => -1, compact => 0, max_size => undef, fsync => 1 };
+my $opt = { quiet => -1, compact => 0, fsync => 1, scan => 1 };
 GetOptions($opt, qw(verbose|v+ reindex rethread compact|c+ jobs|j=i
 		fsync|sync!
 		indexlevel|index-level|L=s max_size|max-size=s
 		batch_size|batch-size=s
-		gc commit-interval=i watch
+		gc commit-interval=i watch scan!
 		all help|h))
 	or die $help;
 if ($opt->{help}) { print $help; exit 0 };