Delete merge_request_metrics -> ci_pipelines FK

db/post_migrate/20211213102111_drop_ci_pipelines_mr_metrics_fk.rb

+# frozen_string_literal: true
+
+class DropCiPipelinesMrMetricsFk < Gitlab::Database::Migration[1.0]
+  disable_ddl_transaction!
+
+  def up
+    with_lock_retries do
+      remove_foreign_key_if_exists(:merge_request_metrics, :ci_pipelines, name: "fk_rails_33ae169d48")
+    end
+  end
+
+  def down
+    add_concurrent_foreign_key(:merge_request_metrics, :ci_pipelines, name: "fk_rails_33ae169d48", column: :pipeline_id, target_column: :id, on_delete: "cascade")
+  end
+end

db/schema_migrations/20211213102111

+3d011cc67fc6ac661788f2d0e3766e51d624a4248ac9dbd861a4db810d396091
\ No newline at end of file

db/structure.sql

@@ -30328,9 +30328,6 @@ ALTER TABLE ONLY container_repositories
 ALTER TABLE ONLY clusters_applications_jupyter
     ADD CONSTRAINT fk_rails_331f0aff78 FOREIGN KEY (oauth_application_id) REFERENCES oauth_applications(id) ON DELETE SET NULL;
 
-ALTER TABLE ONLY merge_request_metrics
-    ADD CONSTRAINT fk_rails_33ae169d48 FOREIGN KEY (pipeline_id) REFERENCES ci_pipelines(id) ON DELETE CASCADE;
-
 ALTER TABLE ONLY suggestions
     ADD CONSTRAINT fk_rails_33b03a535c FOREIGN KEY (note_id) REFERENCES notes(id) ON DELETE CASCADE;
 

lib/gitlab/database/gitlab_loose_foreign_keys.yml

@@ -45,3 +45,7 @@ terraform_state_versions:
   - table: ci_builds
     column: ci_build_id
     on_delete: async_nullify
+merge_request_metrics:
+  - table: ci_pipelines
+    column: pipeline_id
+    on_delete: async_delete

spec/models/merge_request/metrics_spec.rb

@@ -48,4 +48,10 @@ RSpec.describe MergeRequest::Metrics do
       end
     end
   end
+
+  it_behaves_like 'cleanup by a loose foreign key' do
+    let!(:merge_request) { create(:merge_request) }
+    let!(:parent) { create(:ci_pipeline, project: merge_request.target_project) }
+    let!(:model) { merge_request.metrics.tap { |metrics| metrics.update!(pipeline: parent) } }
+  end
 end

spec/models/terraform/state_version_spec.rb

@@ -92,4 +92,9 @@ RSpec.describe Terraform::StateVersion do
       end
     end
   end
+
+  it_behaves_like 'cleanup by a loose foreign key' do
+    let!(:model) { create(:terraform_state_version) }
+    let!(:parent) { model.build }
+  end
 end

spec/support/shared_examples/loose_foreign_keys/have_loose_foreign_key.rb

@@ -47,3 +47,28 @@ RSpec.shared_examples 'it has loose foreign keys' do
     expect(deleted_records.status_processed.count).to be(1)
   end
 end
+
+RSpec.shared_examples 'cleanup by a loose foreign key' do
+  let(:foreign_key_definition) do
+    foreign_keys_for_parent = Gitlab::Database::LooseForeignKeys.definitions_by_table[parent.class.table_name]
+    foreign_keys_for_parent.find { |definition| definition.from_table == model.class.table_name }
+  end
+
+  def find_model
+    model.class.find_by(id: model.id)
+  end
+
+  it 'deletes the model' do
+    parent.delete
+
+    expect(find_model).to be_present
+
+    LooseForeignKeys::ProcessDeletedRecordsService.new(connection: model.connection).execute
+
+    if foreign_key_definition.on_delete.eql?(:async_delete)
+      expect(find_model).not_to be_present
+    else
+      expect(find_model[foreign_key_definition.column]).to eq(nil)
+    end
+  end
+end