Reorder migrations to add index first

Move patch_prometheus_services_for_shared_cluster_applications after
index on type in services table is added

db/post_migrate/20191220102807_patch_prometheus_services_for_shared_cluster_applications.rb

-# frozen_string_literal: true
-
-class PatchPrometheusServicesForSharedClusterApplications < ActiveRecord::Migration[5.2]
-  include Gitlab::Database::MigrationHelpers
-
-  DOWNTIME = false
-  MIGRATION = 'ActivatePrometheusServicesForSharedClusterApplications'.freeze
-  BATCH_SIZE = 500
-  DELAY = 2.minutes
-
-  disable_ddl_transaction!
-
-  module Migratable
-    module Applications
-      class Prometheus < ActiveRecord::Base
-        self.table_name = 'clusters_applications_prometheus'
-
-        enum status: {
-          errored: -1,
-          installed: 3,
-          updated: 5
-        }
-      end
-    end
-
-    class Project < ActiveRecord::Base
-      self.table_name = 'projects'
-      include ::EachBatch
-
-      scope :with_application_on_group_clusters, -> {
-        joins("INNER JOIN namespaces ON namespaces.id = projects.namespace_id")
-          .joins("INNER JOIN cluster_groups ON cluster_groups.group_id = namespaces.id")
-          .joins("INNER JOIN clusters ON clusters.id = cluster_groups.cluster_id AND clusters.cluster_type = #{Cluster.cluster_types['group_type']}")
-          .joins("INNER JOIN clusters_applications_prometheus ON clusters_applications_prometheus.cluster_id = clusters.id
-                      AND clusters_applications_prometheus.status IN (#{Applications::Prometheus.statuses[:installed]}, #{Applications::Prometheus.statuses[:updated]})")
-      }
-
-      scope :without_active_prometheus_services, -> {
-        joins("LEFT JOIN services ON services.project_id = projects.id AND services.type = 'PrometheusService'")
-          .where("services.id IS NULL OR (services.active = FALSE AND services.properties = '{}')")
-      }
-    end
-
-    class Cluster < ActiveRecord::Base
-      self.table_name = 'clusters'
-
-      enum cluster_type: {
-        instance_type: 1,
-        group_type: 2
-      }
-
-      def self.has_prometheus_application?
-        joins("INNER JOIN clusters_applications_prometheus ON clusters_applications_prometheus.cluster_id = clusters.id
-                   AND clusters_applications_prometheus.status IN (#{Applications::Prometheus.statuses[:installed]}, #{Applications::Prometheus.statuses[:updated]})").exists?
-      end
-    end
-  end
-
-  def up
-    projects_without_active_prometheus_service.group('projects.id').each_batch(of: BATCH_SIZE) do |batch, index|
-      bg_migrations_batch = batch.select('projects.id').map { |project| [MIGRATION, project.id] }
-      delay = index * DELAY
-      BackgroundMigrationWorker.bulk_perform_in(delay.seconds, bg_migrations_batch)
-    end
-  end
-
-  def down
-    # no-op
-  end
-
-  private
-
-  def projects_without_active_prometheus_service
-    scope = Migratable::Project.without_active_prometheus_services
-
-    return scope if migrate_instance_cluster?
-
-    scope.with_application_on_group_clusters
-  end
-
-  def migrate_instance_cluster?
-    if instance_variable_defined?('@migrate_instance_cluster')
-      @migrate_instance_cluster
-    else
-      @migrate_instance_cluster = Migratable::Cluster.instance_type.has_prometheus_application?
-    end
-  end
-end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 2020_01_14_112932) do
+ActiveRecord::Schema.define(version: 2020_01_14_113341) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "pg_trgm"

spec/lib/gitlab/background_migration/activate_prometheus_services_for_shared_cluster_applications_spec.rb

@@ -2,7 +2,7 @@
 
 require 'spec_helper'
 
-describe Gitlab::BackgroundMigration::ActivatePrometheusServicesForSharedClusterApplications, :migration, schema: 2019_12_20_102807 do
+describe Gitlab::BackgroundMigration::ActivatePrometheusServicesForSharedClusterApplications, :migration, schema: 2020_01_14_113341 do
   include MigrationHelpers::PrometheusServiceHelpers
 
   let(:namespaces) { table(:namespaces) }

spec/migrations/patch_prometheus_services_for_shared_cluster_applications_spec.rb

 # frozen_string_literal: true
 
 require 'spec_helper'
-require Rails.root.join('db', 'post_migrate', '20191220102807_patch_prometheus_services_for_shared_cluster_applications.rb')
+require Rails.root.join('db', 'post_migrate', '20200114113341_patch_prometheus_services_for_shared_cluster_applications.rb')
 
 describe PatchPrometheusServicesForSharedClusterApplications, :migration, :sidekiq do
   include MigrationHelpers::PrometheusServiceHelpers