Schedule pipeline stages index background migration

db/post_migrate/20180420080616_schedule_stages_index_migration.rb

+class ScheduleStagesIndexMigration < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+  MIGRATION = 'MigrateStageIndex'.freeze
+  BATCH_SIZE = 2000
+
+  disable_ddl_transaction!
+
+  class Stage < ActiveRecord::Base
+    include EachBatch
+    self.table_name = 'ci_stages'
+  end
+
+  def up
+    disable_statement_timeout
+
+    Stage.all.tap do |relation|
+      queue_background_migration_jobs_by_range_at_intervals(relation,
+                                                            MIGRATION,
+                                                            5.minutes,
+                                                            batch_size: BATCH_SIZE)
+    end
+  end
+
+  def down
+    # noop
+  end
+end

db/schema.rb

@@ -11,7 +11,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20180418053107) do
+ActiveRecord::Schema.define(version: 20180420080616) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"

spec/migrations/schedule_stages_index_migration_spec.rb

+require 'spec_helper'
+require Rails.root.join('db', 'post_migrate', '20180420080616_schedule_stages_index_migration')
+
+describe ScheduleStagesIndexMigration, :sidekiq, :migration do
+  let(:namespaces) { table(:namespaces) }
+  let(:projects) { table(:projects) }
+  let(:pipelines) { table(:ci_pipelines) }
+  let(:stages) { table(:ci_stages) }
+
+  before do
+    stub_const("#{described_class}::BATCH_SIZE", 1)
+
+    namespaces.create(id: 12, name: 'gitlab-org', path: 'gitlab-org')
+    projects.create!(id: 123, namespace_id: 12, name: 'gitlab', path: 'gitlab')
+    pipelines.create!(id: 1, project_id: 123, ref: 'master', sha: 'adf43c3a')
+    stages.create!(id: 121, project_id: 123, pipeline_id: 1, name: 'build')
+    stages.create!(id: 122, project_id: 123, pipeline_id: 1, name: 'test')
+    stages.create!(id: 123, project_id: 123, pipeline_id: 1, name: 'deploy')
+  end
+
+  it 'schedules delayed background migrations in batches' do
+    Sidekiq::Testing.fake! do
+      Timecop.freeze do
+        expect(stages.all).to all(have_attributes(index: be_nil))
+
+        migrate!
+
+        expect(described_class::MIGRATION).to be_scheduled_delayed_migration(5.minutes, 121, 121)
+        expect(described_class::MIGRATION).to be_scheduled_delayed_migration(10.minutes, 122, 122)
+        expect(described_class::MIGRATION).to be_scheduled_delayed_migration(15.minutes, 123, 123)
+        expect(BackgroundMigrationWorker.jobs.size).to eq 3
+      end
+    end
+  end
+end