class PopulateEditionsPart1 < ActiveRecord::Migration[5.0]
  def up
    execute "UPDATE content_items SET document_id = (
               SELECT id FROM documents
               WHERE documents.content_id = content_items.content_id AND
                  documents.locale = content_items.locale
             )"
  end
end

class PopulateEditionsPart1 < ActiveRecord::Migration[5.0]
  disable_ddl_transaction!

  def up
    execute "UPDATE content_items SET document_id = (
               SELECT id FROM documents
               WHERE documents.content_id = content_items.content_id AND
                  documents.locale = content_items.locale
             )"
  end
end

Change query to not use a transaction
Change query to not use a transaction
