Improve performance of `Pipeline.newest_first`

app/models/ci/pipeline.rb

@@ -194,22 +194,24 @@ module Ci
     #
     # ref - The name (or names) of the branch(es)/tag(s) to limit the list of
     #       pipelines to.
-    def self.newest_first(ref = nil)
+    # limit - This limits a backlog search, default to 100.
+    def self.newest_first(ref: nil, limit: 100)
       relation = order(id: :desc)
-
-      ref ? relation.where(ref: ref) : relation
+      relation = relation.where(ref: ref) if ref
+      relation = relation.where(id: relation.limit(limit).select(:id)) if limit
+      relation
     end
 
     def self.latest_status(ref = nil)
-      newest_first(ref).pluck(:status).first
+      newest_first(ref: ref).pluck(:status).first
     end
 
     def self.latest_successful_for(ref)
-      newest_first(ref).success.take
+      newest_first(ref: ref).success.take
     end
 
     def self.latest_successful_for_refs(refs)
-      relation = newest_first(refs).success
+      relation = newest_first(ref: refs).success
 
       relation.each_with_object({}) do |pipeline, hash|
         hash[pipeline.ref] ||= pipeline

ee/app/models/ee/ci/pipeline.rb

@@ -22,7 +22,7 @@ module EE
 
         # The new `reports:` syntax reports
         scope :with_security_reports, -> do
-          where('EXISTS (?)', Ci::Build.select(1).latest.with_security_reports.where('ci_pipelines.id=ci_build.commit_id'))
+          where('EXISTS (?)', ::Ci::Build.latest.with_security_reports.where('ci_pipelines.id=ci_builds.commit_id').select(1))
         end
 
         # This structure describes feature levels

ee/app/models/ee/project.rb

@@ -110,8 +110,8 @@ module EE
     end
 
     def latest_pipeline_with_security_reports
-      pipelines.newest_first(default_branch).with_security_reports.first ||
-        pipelines.newest_first(default_branch).with_legacy_security_reports.first
+      pipelines.newest_first(ref: default_branch).with_security_reports.first ||
+        pipelines.newest_first(ref: default_branch).with_legacy_security_reports.first
     end
 
     def environments_for_scope(scope)

ee/spec/models/project_spec.rb

@@ -1498,17 +1498,42 @@ describe Project do
 
   describe '#latest_pipeline_with_security_reports' do
     let(:project) { create(:project) }
-    let(:pipeline_1) { create(:ci_pipeline_without_jobs, project: project) }
-    let(:pipeline_2) { create(:ci_pipeline_without_jobs, project: project) }
-    let(:pipeline_3) { create(:ci_pipeline_without_jobs, project: project) }
+    let!(:pipeline_1) { create(:ci_pipeline_without_jobs, project: project) }
+    let!(:pipeline_2) { create(:ci_pipeline_without_jobs, project: project) }
+    let!(:pipeline_3) { create(:ci_pipeline_without_jobs, project: project) }
 
+    subject { project.latest_pipeline_with_security_reports }
+
+    context 'when legacy reports are used' do
       before do
         create(:ee_ci_build, :legacy_sast, pipeline: pipeline_1)
         create(:ee_ci_build, :legacy_sast, pipeline: pipeline_2)
       end
 
       it "returns the latest pipeline with security reports" do
-      expect(project.latest_pipeline_with_legacy_security_reports).to eq(pipeline_2)
+        is_expected.to eq(pipeline_2)
+      end
+    end
+
+    context 'when new reports are used' do
+      before do
+        create(:ee_ci_build, :sast, pipeline: pipeline_1)
+        create(:ee_ci_build, :sast, pipeline: pipeline_2)
+      end
+
+      it "returns the latest pipeline with security reports" do
+        is_expected.to eq(pipeline_2)
+      end
+
+      context 'when legacy used' do
+        before do
+          create(:ee_ci_build, :legacy_sast, pipeline: pipeline_3)
+        end
+
+        it "prefers the new reports" do
+          is_expected.to eq(pipeline_2)
+        end
+      end
     end
   end