lib/PublicInbox/Msgmap.pm | 4 ++++

diff --git a/lib/PublicInbox/Msgmap.pm b/lib/PublicInbox/Msgmap.pm
index 9523752e9af07f8b973ac45d5a5aeda408801513..5fe14383ac484a79e1b279b718e28db68b5449d4 100644
--- a/lib/PublicInbox/Msgmap.pm
+++ b/lib/PublicInbox/Msgmap.pm
@@ -48,6 +48,10 @@ 	my $self = bless { dbh => $dbh }, $class;
 
 	if ($writable) {
 		create_tables($dbh);
+
+		# TRUNCATE reduces I/O compared to the default (DELETE)
+		$dbh->do('PRAGMA journal_mode = TRUNCATE');
+
 		$dbh->begin_work;
 		$self->created_at(time) unless $self->created_at;