Change query in finder

WIP on changes

Refactor finder to use more efficient sql query

app/models/event.rb

@@ -76,6 +76,7 @@ class Event < ApplicationRecord
   # Scopes
   scope :recent, -> { reorder(id: :desc) }
   scope :code_push, -> { where(action: PUSHED) }
+  scope :merged, -> { where(action: MERGED) }
 
   scope :with_associations, -> do
     # We're using preload for "push_event_payload" as otherwise the association

ee/app/controllers/groups/security/compliance_dashboards_controller.rb

@@ -5,12 +5,11 @@ class Groups::Security::ComplianceDashboardsController < Groups::ApplicationCont
   before_action :authorize_compliance_dashboard!
 
   def show
-    preload_for_collection = [:target_project, :metrics, :approved_by_users, source_project: :route, target_project: :namespace]
+    preload_for_collection = [:approved_by_users, :metrics, source_project: :route, target_project: :namespace]
 
-    @merge_requests = MergeRequestsComplianceFinder.new(current_user, { group_id: @group.id })
+    @merge_requests = MergeRequestsComplianceFinder.new(current_user, { group_id: @group.id, preloads: preload_for_collection })
       .execute
-      .preload(preload_for_collection) # rubocop: disable CodeReuse/ActiveRecord
-      .page(params[:page])
+    @merge_requests = Kaminari.paginate_array(@merge_requests).page(params[:page])
   end
 
   private

ee/app/finders/merge_requests_compliance_finder.rb

@@ -8,17 +8,22 @@
 #   current_user - which user use
 #   params:
 #     group_id: integer
+#     preloads: array of associations to preload
 #
 class MergeRequestsComplianceFinder < MergeRequestsFinder
   def execute
-    sql = super
-      .select('DISTINCT ON (merge_requests.target_project_id) merge_requests.*, merge_request_metrics.merged_at')
+    # rubocop: disable CodeReuse/ActiveRecord
+    lateral = Event
+      .select(:created_at, :target_id)
+      .where('projects.id = project_id')
+      .merged
+      .recent
+      .limit(1)
       .to_sql
 
-    # rubocop: disable CodeReuse/ActiveRecord
-    MergeRequest
-      .from([Arel.sql("(#{sql}) AS #{MergeRequest.table_name}")])
-      .order('merged_at DESC')
+    sql = find_group_projects.as('projects').to_sql
+    records = Project.select('projects.id, events.target_id as merge_request_id').from([Arel.sql("#{sql} JOIN LATERAL (#{lateral}) #{Event.table_name} ON true")]).order('events.created_at DESC')
+    select_sorted_mrs(records)
     # rubocop: enable CodeReuse/ActiveRecord
   end
 
@@ -26,12 +31,20 @@ class MergeRequestsComplianceFinder < MergeRequestsFinder
 
   def params
     finder_options = {
-      scope: :all,
-      state: :merged,
-      sort: :by_merged_at,
       include_subgroups: true,
       attempt_group_search_optimizations: true
     }
     super.merge(finder_options)
   end
+
+  def select_sorted_mrs(records)
+    hash = {}
+    records.each { |row| hash[row['merge_request_id']] = nil }
+    mrs = MergeRequest.where(id: hash.keys).preload(params[:preloads]) # rubocop: disable CodeReuse/ActiveRecord
+
+    mrs.each { |mr| hash[mr.id] = mr }
+
+    hash.compact!
+    hash.values # sorted MRs
+  end
 end

ee/app/models/ee/merge_request.rb

@@ -73,6 +73,7 @@ module EE
       def with_api_entity_associations
         super.preload(:blocking_merge_requests)
       end
+<<<<<<< HEAD
 
       def sort_by_attribute(method, *args)
         if method.to_s == 'review_time_desc'
@@ -91,6 +92,8 @@ module EE
         grouping_columns << ::MergeRequest::Metrics.arel_table[:first_comment_at] if sort.to_s == 'review_time_desc'
         grouping_columns
       end
+=======
+>>>>>>> Change query in finder
     end
 
     override :mergeable?

ee/app/views/groups/security/compliance_dashboards/_merge_request.html.haml

-%li{ id: dom_id(merge_request), class: mr_css_classes(merge_request), data: { id: merge_request.id } }
+%li{ id: dom_id(merge_request), data: { id: merge_request.id } }
   .issuable-info-container
     .issuable-main-info
       .merge-request-title.title

ee/app/views/groups/security/compliance_dashboards/_merge_requests.html.haml

@@ -3,7 +3,7 @@
     %ul.content-list.mr-list.issuable-list
       = render partial: 'merge_request', collection: @merge_requests
 
-  = paginate_without_count @merge_requests
+  = paginate @merge_requests
 
 - else
   = render 'empty_state'

ee/spec/controllers/groups/security/compliance_dashboards_controller_spec.rb

@@ -41,7 +41,7 @@ describe Groups::Security::ComplianceDashboardsController do
           let(:mr_2) { create(:merge_request, source_project: project, source_branch: 'A', state: :merged) }
 
           before do
-            mr_1.metrics.update!(merged_at: 20.minutes.ago)
+            create(:event, :merged, project: project, target: mr_1, author: user)
           end
 
           it 'renders merge request' do

ee/spec/finders/merge_requests_compliance_finder_spec.rb

@@ -17,10 +17,10 @@ describe MergeRequestsComplianceFinder do
   let(:mr_4) { create(:merge_request, source_project: project_2, source_branch: 'A', state: :merged) }
 
   before do
-    mr_1.metrics.update!(merged_at: 20.minutes.ago)
-    mr_2.metrics.update!(merged_at: 40.minutes.ago)
-    mr_3.metrics.update!(merged_at: 30.minutes.ago)
-    mr_4.metrics.update!(merged_at: 50.minutes.ago)
+    create(:event, :merged, project: project_2, target: mr_4, author: current_user, created_at: 50.minutes.ago, id: 1)
+    create(:event, :merged, project: project_2, target: mr_2, author: current_user, created_at: 40.minutes.ago, id: 2)
+    create(:event, :merged, project: project, target: mr_3, author: current_user, created_at: 30.minutes.ago, id: 3)
+    create(:event, :merged, project: project, target: mr_1, author: current_user, created_at: 20.minutes.ago, id: 4)
   end
 
   context 'when there are merge requests from projects in group' do
@@ -40,8 +40,8 @@ describe MergeRequestsComplianceFinder do
       let(:mr_6) { create(:merge_request, source_project: sub_project, state: :merged) }
 
       before do
-        mr_5.metrics.update!(merged_at: 10.minutes.ago)
-        mr_6.metrics.update!(merged_at: 30.minutes.ago)
+        create(:event, :merged, project: sub_project, target: mr_6, author: current_user, created_at: 30.minutes.ago, id: 6)
+        create(:event, :merged, project: sub_project, target: mr_5, author: current_user, created_at: 10.minutes.ago, id: 7)
       end
 
       it 'shows only most recent Merge Request from each project' do