configure_query_cache!

# File activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb, line 182
        def configure_query_cache!
          case query_cache = pool.db_config.query_cache
          when 0, false
            return
          when Integer
            @query_cache_max_size = query_cache
          when nil
            @query_cache_max_size = DEFAULT_SIZE
          else
            @query_cache_max_size = nil # no limit
          end

          if pool.query_cache_enabled
            enable_query_cache!
          end
        end