Optimize projects_enforcing_code_owner_approval qr

Optimizes projects_enforcing_code_owner_approval
counter query for batch counting in usage data
by adding an index

changelogs/unreleased/208923-enable-batch-counting-for-some-individual-queries-1.yml

+---
+title: Optimize projects_enforcing_code_owner_approval counter query performance for usage ping
+merge_request: 27526
+author:
+type: performance

db/migrate/20200318175008_add_index_on_id_and_archived_and_pending_delete_to_projects.rb

+# frozen_string_literal: true
+
+class AddIndexOnIdAndArchivedAndPendingDeleteToProjects < ActiveRecord::Migration[6.0]
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+  INDEX_NAME = 'index_projects_on_id_and_archived_and_pending_delete'
+
+  disable_ddl_transaction!
+
+  def up
+    add_concurrent_index :projects, :id, where: "archived = FALSE AND pending_delete = FALSE", name: INDEX_NAME
+  end
+
+  def down
+    remove_concurrent_index_by_name :projects, INDEX_NAME
+  end
+end

db/structure.sql

@@ -9627,6 +9627,8 @@ CREATE INDEX index_projects_on_creator_id_and_created_at ON public.projects USIN
 
 CREATE INDEX index_projects_on_description_trigram ON public.projects USING gin (description public.gin_trgm_ops);
 
+CREATE INDEX index_projects_on_id_and_archived_and_pending_delete ON public.projects USING btree (id) WHERE ((archived = false) AND (pending_delete = false));
+
 CREATE UNIQUE INDEX index_projects_on_id_partial_for_visibility ON public.projects USING btree (id) WHERE (visibility_level = ANY (ARRAY[10, 20]));
 
 CREATE INDEX index_projects_on_id_service_desk_enabled ON public.projects USING btree (id) WHERE (service_desk_enabled = true);
@@ -12709,6 +12711,7 @@ INSERT INTO "schema_migrations" (version) VALUES
 ('20200318163148'),
 ('20200318164448'),
 ('20200318165448'),
+('20200318175008'),
 ('20200319203901'),
 ('20200323075043');
 

ee/lib/ee/gitlab/usage_data.rb

@@ -149,7 +149,7 @@ module EE
                                          ldap_keys: count(::LDAPKey),
                                          ldap_users: count(::User.ldap, 'users.id'),
                                          pod_logs_usages_total: ::Gitlab::UsageCounters::PodLogs.usage_totals[:total],
-                                         projects_enforcing_code_owner_approval: count(::Project.without_deleted.non_archived.requiring_code_owner_approval, batch: false),
+                                         projects_enforcing_code_owner_approval: count(::Project.without_deleted.non_archived.requiring_code_owner_approval),
                                          merge_requests_with_optional_codeowners: distinct_count(::ApprovalMergeRequestRule.code_owner_approval_optional, :merge_request_id),
                                          merge_requests_with_required_codeowners: distinct_count(::ApprovalMergeRequestRule.code_owner_approval_required, :merge_request_id),
                                          projects_mirrored_with_pipelines_enabled: count(::Project.mirrored_with_enabled_pipelines),