From 1218bee34cf04498ac36add5c7e847698be541c2 Mon Sep 17 00:00:00 2001
From: Eric Wong <e@80x24.org>
Date: Fri, 23 Jul 2021 10:56:11 +0000
Subject: lei: avoid SQLite COUNT() for dedupe

SQLite COUNT() is a slow operation that does a full table scan
with no conditions.  There's no need for it, since lei dedupe
only needs to know if it's empty or not to decide between
new/ and cur/ for Maildir outputs.
---
 lib/PublicInbox/SharedKV.pm | 7 +++++++
 1 file changed, 7 insertions(+)

(limited to 'lib/PublicInbox/SharedKV.pm')

diff --git a/lib/PublicInbox/SharedKV.pm b/lib/PublicInbox/SharedKV.pm
index 8347b195..3487e820 100644
--- a/lib/PublicInbox/SharedKV.pm
+++ b/lib/PublicInbox/SharedKV.pm
@@ -154,6 +154,13 @@ SELECT COUNT(k) FROM kv
 	$sth->fetchrow_array;
 }
 
+# faster than ->count due to how SQLite works
+sub has_entries {
+	my ($self) = @_;
+	my @n = $self->{dbh}->selectrow_array('SELECT k FROM kv LIMIT 1');
+	scalar(@n) ? 1 : undef;
+}
+
 sub dbh_release {
 	my ($self, $lock) = @_;
 	my $dbh = delete $self->{dbh} or return;
-- 
cgit v1.2.3-24-ge0c7