benchmark to compare count vs find

Tests/bench-find-vs-count.pl6

@@ -0,0 +1,56 @@
+#!/usr/bin/env perl6
+
+use v6;
+
+use lib 't';
+use Test-support;
+
+use MongoDB;
+use MongoDB::Client;
+use BSON::Document;
+
+use Bench;
+
+my MongoDB::Test-support $ts .= new;
+my Int $p1 = $ts.server-control.get-port-number('s1');
+my MongoDB::Client $cln .= new( :uri('mongodb://localhost' ~ ":$p1"));
+
+my $db = $cln.database('test');
+my $cl = $db.collection('bench1');
+
+# drop data first
+$db.run-command: (drop => $cl.name,);
+
+# insert a few records
+for ^10 -> $i {
+  my BSON::Document $req .= new: (
+    insert => $cl.name,
+    documents => [
+      BSON::Document.new( (
+          field1 => "test $i",
+          field2 => 'test xyz',
+        )
+      ),
+    ]
+  );
+
+  my BSON::Document $doc = $db.run-command($req);
+  die "insert failed [$i]" unless $doc<ok> == 1;
+}
+
+
+
+my $b = Bench.new;
+$b.cmpthese(
+  100, {
+    find => sub { my $c = $cl.find(); },
+
+    count => sub {
+      my BSON::Document $doc = $db.run-command: (
+        count => $cl.name,
+        query => BSON::Document.new()
+      );
+    }
+  }
+);
+