Use without_count for records paginated with paginate_without_counts

This change adds .without_count to queries of records
that will be paginated using paginate_without_counts,
so that a count query is not triggered during pagination.

ee/app/controllers/admin/audit_logs_controller.rb

@@ -9,7 +9,8 @@ class Admin::AuditLogsController < Admin::ApplicationController
   PER_PAGE = 25
 
   def index
-    @events = AuditLogFinder.new(audit_logs_params).execute.page(params[:page]).per(PER_PAGE)
+    @events = audit_log_events.page(params[:page]).per(PER_PAGE).without_count
+
     @entity = case audit_logs_params[:entity_type]
               when 'User'
                 User.find_by_id(audit_logs_params[:entity_id])
@@ -24,6 +25,10 @@ class Admin::AuditLogsController < Admin::ApplicationController
 
   private
 
+  def audit_log_events
+    AuditLogFinder.new(audit_logs_params).execute
+  end
+
   def check_license_admin_audit_log_available!
     render_404 unless License.feature_available?(:admin_audit_log)
   end

ee/changelogs/unreleased/gitlab-pagination-without-count-fix.yml

+---
+title: Do not trigger count query for pagination without count
+merge_request: 21232
+author:
+type: performance

ee/spec/controllers/admin/audit_logs_controller_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe Admin::AuditLogsController do
+  let(:admin) { create(:admin) }
+
+  describe 'GET #index' do
+    before do
+      sign_in(admin)
+    end
+
+    context 'licensed' do
+      before do
+        stub_licensed_features(admin_audit_log: true)
+      end
+
+      context 'pagination' do
+        it 'paginates audit events, without casting a count query' do
+          create(:user_audit_event, created_at: 5.days.ago)
+
+          get :index, params: { 'entity_type': 'User' }
+
+          expect(assigns(:events)).to be_kind_of(Kaminari::PaginatableWithoutCount)
+        end
+      end
+    end
+  end
+end