         # File lib/ferret/index.rb, line 540
    540:     def query_delete(query)
    541:       @dir.synchronize do
    542:         ensure_writer_open()
    543:         ensure_searcher_open()
    544:         query = do_process_query(query)
    545:         @searcher.search_each(query, :limit => :all) do |doc, score|
    546:           @reader.delete(doc)
    547:         end
    548:         flush() if @auto_flush
    549:       end
    550:     end