Cleanup required migrations

db/migrate/20160331204039_add_action_to_ci_commit.rb

-class AddActionToCiCommit < ActiveRecord::Migration
-  def change
-    add_column :ci_commits, :action, :string
-  end
-end

db/migrate/20160411122626_add_duration_to_ci_commit.rb

-class AddDurationToCiCommit < ActiveRecord::Migration
-  def change
-    add_column :ci_commits, :duration, :integer
-  end
-end

db/migrate/20160331153918_add_fields_to_ci_commit.rb → db/migrate/20160412173416_add_fields_to_ci_commit.rb

@@ -3,5 +3,6 @@ class AddFieldsToCiCommit < ActiveRecord::Migration
     add_column :ci_commits, :status, :string
     add_column :ci_commits, :started_at, :timestamp
     add_column :ci_commits, :finished_at, :timestamp
+    add_column :ci_commits, :duration, :integer
   end
 end

db/migrate/20160412175417_update_ci_commit.rb → db/migrate/20160412173417_update_ci_commit.rb

 class UpdateCiCommit < ActiveRecord::Migration
+  # This migration can be run online, but needs to be executed for the second time after restarting Unicorn workers
+  # Otherwise Offline migration should be used.
   def change
     execute("UPDATE ci_commits SET status=#{status}, ref=#{ref}, tag=#{tag} WHERE status IS NULL")
   end
 
+  private
+
   def status
     builds = '(SELECT COUNT(*) FROM ci_builds WHERE ci_builds.commit_id=ci_commits.id)'
     success = "(SELECT COUNT(*) FROM ci_builds WHERE ci_builds.commit_id=ci_commits.id AND status='success')"

db/migrate/20160412174954_add_ci_commit_indexes.rb → db/migrate/20160412173418_add_ci_commit_indexes.rb

@@ -7,6 +7,8 @@ class AddCiCommitIndexes < ActiveRecord::Migration
     add_index :ci_commits, [:status], index_options
   end
 
+  private
+
   def index_options
     { algorithm: :concurrently } if Gitlab::Database.postgresql?
   end