Schedule stage_id bg migrations in batches of 10

db/post_migrate/20170628080858_migrate_stage_id_reference_in_background.rb

@@ -3,6 +3,7 @@ class MigrateStageIdReferenceInBackground < ActiveRecord::Migration
 
   DOWNTIME = false
   BATCH_SIZE = 10000
+  RANGE_SIZE = 1000
   MIGRATION = 'MigrateBuildStageIdReference'.freeze
 
   disable_ddl_transaction!
@@ -17,10 +18,12 @@ class MigrateStageIdReferenceInBackground < ActiveRecord::Migration
   #
   def up
     Build.all.each_batch(of: BATCH_SIZE) do |relation, index|
-      range = relation.pluck('MIN(id)', 'MAX(id)').first
-      schedule = index * 2.minutes
+      relation.each_batch(of: RANGE_SIZE) do |relation|
+        range = relation.pluck('MIN(id)', 'MAX(id)').first
 
-      BackgroundMigrationWorker.perform_in(schedule, MIGRATION, range)
+        BackgroundMigrationWorker
+          .perform_in(index * 2.minutes, MIGRATION, range)
+      end
     end
   end
 

lib/gitlab/background_migration/migrate_build_stage_id_reference.rb

@@ -2,7 +2,7 @@ module Gitlab
   module BackgroundMigration
     class MigrateBuildStageIdReference
       def perform(start_id, stop_id)
-        scope = if stop_id.nonzero?
+        scope = if stop_id.to_i.nonzero?
                   "ci_builds.id BETWEEN #{start_id.to_i} AND #{stop_id.to_i}"
                 else
                   "ci_builds.id >= #{start_id.to_i}"

spec/migrations/migrate_stage_id_reference_in_background_spec.rb

@@ -21,7 +21,8 @@ describe MigrateStageIdReferenceInBackground, :migration, :sidekiq do
   let(:projects) { table(:projects) }
 
   before do
-    stub_const("#{described_class.name}::BATCH_SIZE", 2)
+    stub_const("#{described_class.name}::BATCH_SIZE", 3)
+    stub_const("#{described_class.name}::RANGE_SIZE", 2)
 
     projects.create!(id: 123, name: 'gitlab1', path: 'gitlab1')
     projects.create!(id: 345, name: 'gitlab2', path: 'gitlab2')
@@ -48,9 +49,10 @@ describe MigrateStageIdReferenceInBackground, :migration, :sidekiq do
         migrate!
 
         expect(described_class::MIGRATION).to be_scheduled_migration(2.minutes, 1, 2)
-        expect(described_class::MIGRATION).to be_scheduled_migration(4.minutes, 3, 4)
-        expect(described_class::MIGRATION).to be_scheduled_migration(6.minutes, 5, 6)
-        expect(BackgroundMigrationWorker.jobs.size).to eq 3
+        expect(described_class::MIGRATION).to be_scheduled_migration(2.minutes, 3, 3)
+        expect(described_class::MIGRATION).to be_scheduled_migration(4.minutes, 4, 5)
+        expect(described_class::MIGRATION).to be_scheduled_migration(4.minutes, 6, 6)
+        expect(BackgroundMigrationWorker.jobs.size).to eq 4
       end
     end
   end