Optimize query for usage ping

Query by adding an index and using batch counting
projects_mirrored_with_pipelines_enabled

changelogs/unreleased/208923-enable-batch-counting-for-some-individual-queries-5.yml

+---
+title: Optimize projects_mirrored_with_pipelines_enabled query performance in usage data
+merge_request: 27110
+author:
+type: performance

db/migrate/20200312160532_add_index_on_mirror_and_id_to_projects.rb

+# frozen_string_literal: true
+
+class AddIndexOnMirrorAndIdToProjects < ActiveRecord::Migration[6.0]
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+  OLD_INDEX_NAME = 'index_projects_on_mirror_and_mirror_trigger_builds_both_true'
+  NEW_INDEX_NAME = 'index_projects_on_mirror_id_where_mirror_and_trigger_builds'
+
+  disable_ddl_transaction!
+
+  def up
+    add_concurrent_index :projects, :id, where: 'mirror = TRUE AND mirror_trigger_builds = TRUE', name: NEW_INDEX_NAME
+    remove_concurrent_index_by_name :projects, OLD_INDEX_NAME
+  end
+
+  def down
+    add_concurrent_index :projects, :id, where: 'mirror IS TRUE AND mirror_trigger_builds IS TRUE', name: OLD_INDEX_NAME
+    remove_concurrent_index_by_name :projects, NEW_INDEX_NAME
+  end
+end

db/schema.rb

@@ -3493,7 +3493,7 @@ ActiveRecord::Schema.define(version: 2020_03_12_163407) do
     t.index ["id"], name: "index_on_id_partial_with_legacy_storage", where: "((storage_version < 2) OR (storage_version IS NULL))"
     t.index ["id"], name: "index_projects_on_id_partial_for_visibility", unique: true, where: "(visibility_level = ANY (ARRAY[10, 20]))"
     t.index ["id"], name: "index_projects_on_id_service_desk_enabled", where: "(service_desk_enabled = true)"
-    t.index ["id"], name: "index_projects_on_mirror_and_mirror_trigger_builds_both_true", where: "((mirror IS TRUE) AND (mirror_trigger_builds IS TRUE))"
+    t.index ["id"], name: "index_projects_on_mirror_id_where_mirror_and_trigger_builds", where: "((mirror = true) AND (mirror_trigger_builds = true))"
     t.index ["last_activity_at", "id"], name: "index_projects_api_last_activity_at_id_desc", order: { id: :desc }
     t.index ["last_activity_at", "id"], name: "index_projects_api_vis20_last_activity_at", where: "(visibility_level = 20)"
     t.index ["last_activity_at", "id"], name: "index_projects_on_last_activity_at_and_id"

ee/lib/ee/gitlab/usage_data.rb

@@ -152,7 +152,7 @@ module EE
                                          projects_enforcing_code_owner_approval: count(::Project.without_deleted.non_archived.requiring_code_owner_approval, batch: false),
                                          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, batch: false),
+                                         projects_mirrored_with_pipelines_enabled: count(::Project.mirrored_with_enabled_pipelines),
                                          projects_reporting_ci_cd_back_to_github: count(::GithubService.without_defaults.active, batch: false),
                                          projects_with_packages: count(::Packages::Package.select('distinct project_id'), batch: false),
                                          projects_with_prometheus_alerts: count(PrometheusAlert.distinct_projects, batch: false),