msgmap: speed up minmax with separate queries

[public-inbox.git] / lib / PublicInbox / Msgmap.pm

diff --git a/lib/PublicInbox/Msgmap.pm b/lib/PublicInbox/Msgmap.pm
index c6a73155401b9bb3c1c6fd4c5adedddb79a01bbf..feef8ba79ab9a657d8135b0c65ca0186dd7bed51 100644 (file)
--- a/lib/PublicInbox/Msgmap.pm
+++ b/lib/PublicInbox/Msgmap.pm
@@ -92,6 +92,14 @@ sub last_commit {
        $self->meta_accessor('last_commit', $commit);
 }
 
+# v2 uses this to keep track of how up-to-date Xapian is
+# old versions may be automatically GC'ed away in the future,
+# but it's a trivial amount of storage.
+sub last_commit_xap {
+       my ($self, $version, $i, $commit) = @_;
+       $self->meta_accessor("last_xap$version-$i", $commit);
+}
+
 sub created_at {
        my ($self, $second) = @_;
        $self->meta_accessor('created_at', $second);
@@ -130,10 +138,14 @@ sub num_for {
 sub minmax {
        my ($self) = @_;
        my $dbh = $self->{dbh};
-       my $sth = $self->{num_minmax} ||=
-               $dbh->prepare('SELECT MIN(num),MAX(num) FROM msgmap');
+       # breaking MIN and MAX into separate queries speeds up from 250ms
+       # to around 700us with 2.7million messages.
+       my $sth = $dbh->prepare_cached('SELECT MIN(num) FROM msgmap', undef, 1);
+       $sth->execute;
+       my $min = $sth->fetchrow_array;
+       $sth = $dbh->prepare_cached('SELECT MAX(num) FROM msgmap', undef, 1);
        $sth->execute;
-        $sth->fetchrow_array;
+       ($min, $sth->fetchrow_array);
 }
 
 sub mid_prefixes {