Optimize Event queries by removing default order

CHANGELOG.md

@@ -21,6 +21,7 @@ Please view this file on the master branch, on stable branches it's out of date.
   - Fix typo in framework css class. !7086 (Daniel Voogsgerd)
   - New issue board list dropdown stays open after adding a new list
   - Fix: Backup restore doesn't clear cache
+  - Optimize Event queries by removing default order
   - API: Fix project deploy keys 400 and 500 errors when adding an existing key. !6784 (Joshua Welsh)
   - Replace jquery.cookie plugin with js.cookie !7085
   - Use MergeRequestsClosingIssues cache data on Issue#closed_by_merge_requests method

app/models/event.rb

 class Event < ActiveRecord::Base
   include Sortable
-  default_scope { where.not(author_id: nil) }
+  default_scope { reorder(nil).where.not(author_id: nil) }
 
   CREATED   = 1
   UPDATED   = 2

spec/controllers/projects/milestones_controller_spec.rb

@@ -20,7 +20,7 @@ describe Projects::MilestonesController do
       delete :destroy, namespace_id: project.namespace.id, project_id: project.id, id: milestone.iid, format: :js
       expect(response).to be_success
 
-      expect(Event.first.action).to eq(Event::DESTROYED)
+      expect(Event.recent.first.action).to eq(Event::DESTROYED)
 
       expect { Milestone.find(milestone.id) }.to raise_exception(ActiveRecord::RecordNotFound)
       issue.reload

spec/models/members/project_member_spec.rb

@@ -57,12 +57,12 @@ describe ProjectMember, models: true do
     it "creates an expired event when left due to expiry" do
       expired = create(:project_member, project: project, expires_at: Time.now - 6.days)
       expired.destroy
-      expect(Event.first.action).to eq(Event::EXPIRED)
+      expect(Event.recent.first.action).to eq(Event::EXPIRED)
     end
 
     it "creates a left event when left due to leave" do
       master.destroy
-      expect(Event.first.action).to eq(Event::LEFT)
+      expect(Event.recent.first.action).to eq(Event::LEFT)
     end
 
     it "destroys itself and delete associated todos" do

spec/services/milestones/close_service_spec.rb

@@ -18,7 +18,7 @@ describe Milestones::CloseService, services: true do
     it { expect(milestone).to be_closed }
 
     describe :event do
-      let(:event) { Event.first }
+      let(:event) { Event.recent.first }
 
       it { expect(event.milestone).to be_truthy }
       it { expect(event.target).to eq(milestone) }