Merge remote-tracking branch 'public/trending-projects-performance'

2 files changed, 16 insertions, 9 deletions

diff --git a/app/finders/trending_projects_finder.rb b/app/finders/trending_projects_finder.rb
index 9ea342cb26d..81a12403801 100644
--- a/app/finders/trending_projects_finder.rb
+++ b/app/finders/trending_projects_finder.rb
@@ -1,13 +1,6 @@
 class TrendingProjectsFinder
-  def execute(current_user, start_date = nil)
-    start_date ||= Date.today - 1.month
-
-    projects = projects_for(current_user)
-
-    # Determine trending projects based on comments count
-    # for period of time - ex. month
-    projects.joins(:notes).where('notes.created_at > ?', start_date).
-      group("projects.id").reorder("count(notes.id) DESC")
+  def execute(current_user, start_date = 1.month.ago)
+    projects_for(current_user).trending(start_date)
   end
 
   private
diff --git a/app/models/project.rb b/app/models/project.rb
index bb47b9abb03..4661522b8a0 100644
--- a/app/models/project.rb
+++ b/app/models/project.rb
@@ -260,6 +260,20 @@ class Project < ActiveRecord::Base
       name_pattern = Gitlab::Regex::NAMESPACE_REGEX_STR
       %r{(?<project>#{name_pattern}/#{name_pattern})}
     end
+
+    def trending(since = 1.month.ago)
+      # By counting in the JOIN we don't expose the GROUP BY to the outer query.
+      # This means that calls such as "any?" and "count" just return a number of
+      # the total count, instead of the counts grouped per project as a Hash.
+      join_body = "INNER JOIN (
+        SELECT project_id, COUNT(*) AS amount
+        FROM notes
+        WHERE created_at >= #{sanitize(since)}
+        GROUP BY project_id
+      ) join_note_counts ON projects.id = join_note_counts.project_id"
+
+      joins(join_body).reorder('join_note_counts.amount DESC')
+    end
   end
 
   def team